Glossary of cellular and molecular biology (M–Z) (this page) lists terms beginning with the letters M through Z.
This glossary is intended as introductory material for novices (for more specific and technical detail, see the article corresponding to each term). It has been designed as a companion to Glossary of genetics and evolutionary biology, which contains many overlapping and related terms; other related glossaries include Glossary of virology and Glossary of chemistry.
Any very large molecule composed of dozens, hundreds, or thousands of covalently bonded atoms, especially one with biological significance. Many important Шаблон:Gli, such as Шаблон:Gli and Шаблон:Gli, are Шаблон:Gli consisting of a repeated series of smaller Шаблон:Gli; others such as Шаблон:Gli and Шаблон:Gli may not be polymeric but are nevertheless large and complex molecules.
Any of a class of relatively long-lived Шаблон:Gli of the mammalian immune system which are activated in response to the presence of foreign materials in certain tissues and subsequently play important roles in antigen presentation, stimulating other types of immune cells, and killing or Шаблон:Gli parasitic microorganisms, diseased cells, or tumor cells.[3]
The branch of medicine and medical science that involves the study, diagnosis, and management of Шаблон:Gli, and more broadly the application of knowledge about human Шаблон:Gli to medical care.
A specialized type of Шаблон:Gli that occurs exclusively in sexually reproducingeukaryotes, during which Шаблон:Gli is followed by two consecutive rounds of division to ultimately produce four genetically unique Шаблон:Gli daughter cells, each with half the number of Шаблон:Gli as the original Шаблон:Gli parent cell. Meiosis only occurs in cells of the sex organs, and serves the purpose of generating haploid Шаблон:Gli such as sperm, eggs, or spores, which are later fused during fertilization. The two meiotic divisions, known as Meiosis I and Meiosis II, may also include various Шаблон:Gli events between Шаблон:Gli.
A supramolecular aggregate of amphipathicШаблон:Gli molecules which when suspended in a polar solvent tend to arrange themselves into structures which minimize the exposure of their Шаблон:Gli tails by sheltering them within a ball created by their own Шаблон:Gli heads (i.e. a micelle). Certain types of lipids, specifically Шаблон:Gli and other Шаблон:Gli, commonly occur as Шаблон:Gli sheets of molecules when immersed in an aqueous environment, which can themselves assume approximately spherical shapes, acting as semipermeable barriers surrounding a water-filled interior space. This is the basic structure of the biological membranes enclosing all Шаблон:Gli, Шаблон:Gli, and Шаблон:Gli.
Any of a class of Шаблон:GliШаблон:Gli molecules which function as molecular messengers, carrying sequence information encoded in the Шаблон:Gli genome to the Шаблон:Gli where protein synthesis occurs. The primary products of Шаблон:Gli, mRNAs are synthesized by Шаблон:Gli, which builds a chain of Шаблон:Gli that complement the Шаблон:Gli of a Шаблон:Gli; in this way, the DNA sequence of a protein-coding Шаблон:Gli is effectively preserved in the Шаблон:Gli, which is subsequently processed into a mature mRNA by a series of Шаблон:Gli.
The structure of a typical mature protein-coding Шаблон:Gli or mRNA, drawn approximately to scale. The coding sequence (green) is bounded by Шаблон:Gli at both the Шаблон:Gli (yellow) and the Шаблон:Gli (pink). Prior to export from the nucleus, a Шаблон:Gli (red) and a Шаблон:Gli (black) are added to help stabilize the mRNA and prevent its degradation by ribonucleases.
A stepwise series of biochemical reactions occurring within a cell, often but not necessarily Шаблон:Gli by specific Шаблон:Gli, that fulfills some activity or process related to Шаблон:Gli. The reactions are linked by the sharing of reactants, products, or intermediate compounds in consecutive steps, such that the product of one reaction is used as a reactant in a subsequent reaction. Byproducts are often removed from the cell as Шаблон:Gli. The overall pathway may be Шаблон:Gli, Шаблон:Gli, or Шаблон:Gli in nature.[5] In any actively metabolizing cell, an elaborate network of interconnected metabolic pathways is required to maintain Шаблон:Gli, with degradative catabolic processes providing the energy necessary to conduct anabolic biosynthesis; for example, Шаблон:Gli, the Шаблон:Gli, and Шаблон:Gli provide the Шаблон:Gli used in fatty acid synthesis. The flux of Шаблон:Gli through each pathway is regulated by the needs of the cell and the availability of Шаблон:Gli.
The complete set of chemical reactions which sustain and account for the basic processes of life in all living cells,[2] especially those involving: 1) the conversion of energy from food into energy available for cellular activities; 2) the breakdown of food into simpler compounds which can then be used as Шаблон:Gli to build complex Шаблон:Gli such as Шаблон:Gli, Шаблон:Gli, and Шаблон:Gli; and 3) the degradation and excretion of toxins, byproducts, and other unusable compounds known as Шаблон:Gli. In a broader sense the term may include all chemical reactions occurring in living organisms, even those which are not strictly necessary for life but instead serve accessory functions. Many specific cellular activities are accomplished by Шаблон:Gli in which one chemical is ultimately transformed through a stepwise series of reactions into another chemical, with each reaction Шаблон:Gli by a specific Шаблон:Gli. Most metabolic reactions can be subclassified as Шаблон:Gli or Шаблон:Gli.
An intermediate or end product of Шаблон:Gli, especially degradative metabolism (Шаблон:Gli);[2] or any substance produced by or taking part in a metabolic reaction. Metabolites include a huge variety of small molecules generated by cells from various Шаблон:Gli and having various functions, including as inputs to other pathways and reactions, as Шаблон:Gli molecules, and as stimulators, inhibitors, and Шаблон:Gli of Шаблон:Gli. Metabolites may result from the degradation and elimination of naturally occurring compounds as well as of synthetic compounds such as pharmaceuticals.
(of a linear Шаблон:Gli or chromosome fragment) Having a Шаблон:Gli positioned in the middle of the chromosome, resulting in Шаблон:Gli arms of approximately equal length.[6]
The covalent attachment of a methyl group (Шаблон:Chem) to a chemical compound, protein, or other biomolecule, either spontaneously or by Шаблон:Gli catalysis. Methylation is one of the most widespread natural mechanisms by which Шаблон:Gli and Шаблон:Gli are Шаблон:Gli. The Шаблон:Gli in a DNA molecule inhibits recognition of the methylated sequence by Шаблон:Gli, which can effectively Шаблон:Gli the expression of genes. Specific Шаблон:Gli within Шаблон:Gli are also commonly methylated, which can change Шаблон:Gli positioning and similarly Шаблон:Gli or Шаблон:Gli nearby loci. The opposite reaction is Шаблон:Gli.
A group that "aims to provide a standard for the representation of Шаблон:GliШаблон:Gli data that would facilitate the exchange of microarray information between different data systems".[7]
Any of a diverse class of small Шаблон:Gli or Шаблон:Gli found in the cells of many eukaryotes, especially plants and animals, usually having some specific metabolic function and occurring in great numbers in certain specialized cell types. Шаблон:Gli, Шаблон:Gli, Шаблон:Gli, and Шаблон:Gli are often considered microbodies.
A Шаблон:GliШаблон:Gli that is too short to cause any apparent change in morphology under a light microscope, though it may still be detectable with other methods such as Шаблон:Gli.
A long, thin, flexible, rod-like structure composed of polymeric strands of proteins, usually actins, that occurs in abundance in the Шаблон:Gli of eukaryotic cells, forming part of the Шаблон:Gli. Microfilaments comprise the cell's structural framework. They are modified by and interact with numerous other cytoplasmic proteins, playing important roles in cell stability, motility, contractility, and facilitating changes in cell shape, as well as in Шаблон:Gli.
The smaller of the two types of Шаблон:Gli that occur in pairs in the cells of some ciliated protozoa. Whereas the larger Шаблон:Gli is Шаблон:Gli, the micronucleus is Шаблон:Gli and generally transcriptionally inactive except for the purpose of sexual reproduction, where it has important functions during Шаблон:Gli.[2]
A type of Шаблон:Gli consisting of a relatively short Шаблон:Gli of Шаблон:Gli, in which certain Шаблон:Gli (ranging in length from one to six or more Шаблон:Gli) are repeated, typically 5–50 times. Microsatellites are widespread throughout most organisms' genomes and tend to have higher mutation rates than other regions. They are classified as Шаблон:Gli (VNTR) DNA, along with longer Шаблон:Gli.
An instrument used to cut extremely thin slices of material, known as microsections or simply sections, preparatory to observation under a microscope.[5] Sections of tissues and cells are usually 50 nanometres (nm) to 100 micrometres (μm) in width. The process of cutting them is known as microtomy.
Any of the long, generally straight, hollow tubes, about 24 nanometers in diameter and composed of interwoven polymeric filaments of the protein tubulin, found in the cytoplasm of many eukaryotic cells, where they are involved in maintaining the cell's shape and structural integrity as well as in force generation for cellular or Шаблон:Gli locomotion (as with Шаблон:Gli and Шаблон:Gli). They also comprise the Шаблон:Gli critical to Шаблон:Gli and Шаблон:Gli. Microtubules are rigid but transient all-purpose structural members which can be rapidly assembled and disassembled at the cell's needs. Many different microtubule-associated proteins interact with them.[5] See also Шаблон:Gli.
A region near the center of a eukaryotic cell typically consisting of two Шаблон:Gli oriented at right angles to each other and surrounded by a Шаблон:Gli of associated proteins, which functions as the site of initiation for the assembly of Шаблон:Gli.[5]
A type of Шаблон:Gli released when an evagination of the Шаблон:Gli "buds off" into the extracellular space. Microvesicles vary in size from 30–1,000 nanometres in diameter and are thought to play roles in many physiological processes, including Шаблон:Gli by shuttling molecules such as RNA and proteins between cells.[8]
A small, slender, tubular cytoplasmic projection, generally 0.2–4 micrometres long and 0.1 micrometres in diameter,[9] protruding from the surface of some animal cells and supported by a central core of Шаблон:Gli. When present in large numbers, such as on Шаблон:Gli cells lining the respiratory and alimentary tracts, they form a dense brush border which presumably serves to increase each cell's absorptive surface area.[2][3]
The centrally constricted region that forms across the central axis of a cell during Шаблон:Gli, constricted by the closing of the Шаблон:Gli until the Шаблон:Gli are finally separated,[2] but occasionally persisting as a tether between the two cells for as long as a complete Шаблон:Gli.[9]
In plant cells, the outermost layer of the Шаблон:Gli; a continuous, unified layer of extracellular pectins which is the first layer deposited by the cell during Шаблон:Gli and which serves to cement together the primary cell walls of adjacent cells.[4]
A region of Шаблон:Gli, Шаблон:GliШаблон:Gli in which certain DNA Шаблон:Gli (typically 10–60 bases in length) are Шаблон:Gli (typically 5–50 times). In the human genome, minisatellites occur at more than 1,000 loci, especially in Шаблон:Gli and Шаблон:Gli, and exhibit high mutation rates and high variability between individuals. Like the shorter Шаблон:Gli, they are classified as Шаблон:Gli (VNTRs) and are a type of Шаблон:Gli.
An incorrect Шаблон:Gli of Шаблон:Gli on Шаблон:GliШаблон:Gli of Шаблон:Gli or Шаблон:Gli; i.e. the presence in one strand of a duplex molecule of a base that is not complementary (by Watson–Crick pairing rules) to the base occupying the corresponding position in the other strand, which prevents normal hydrogen bonding between the bases. For example, a Шаблон:Gli paired with a Шаблон:Gli would be a mismatch, as guanine normally pairs with Шаблон:Gli.[13]
The set of DNA molecules contained within Шаблон:Gli, usually one or more circular Шаблон:Gli representing a semi-autonomous Шаблон:Gli which is physically separate from and functionally independent of the Шаблон:Gli in the cell's nucleus. The mitochondrial genome encodes many unique enzymes found only in mitochondria.
A highly pleiomorphic Шаблон:Gli found in the Шаблон:Gli of nearly all eukaryotic cells, usually in large numbers in the form of sausage-shaped structures 5–10 micrometres in length,[9] enclosed by a double membrane, with the inner membrane infolded in an elaborate series of Шаблон:Gli so as to maximize surface area. Mitochondria are the primary sites of Шаблон:Gli synthesis, where ATP is regenerated from Шаблон:Gli via Шаблон:Gli, as well as many supporting pathways, including the Шаблон:Gli and the Шаблон:Gli.[3] Like other Шаблон:Gli, mitochondria contain Шаблон:Gli encoded in Шаблон:Gli molecules which replicate independently of the Шаблон:Gli, as well as their own unique set of Шаблон:Gli, Шаблон:Gli, Шаблон:Gli, Шаблон:Gli, and Шаблон:Gli with which to direct transcription and translation of their genes. The majority of the Шаблон:Gli found in mitochondria are encoded by nuclear genes, however, such that mitochondria are only partially autonomous.[2] These observations suggest mitochondria evolved from symbioticШаблон:Gli living inside eukaryotic cells.
The selective degradation of Шаблон:Gli by means of Шаблон:Gli; i.e. the mitochondrion initiates its own degradation. Mitophagy is a regular process in healthy populations of cells by which defective or damaged mitochondria are recycled, preventing their accumulation. It may also occur in response to the changing Шаблон:Gli needs of the cell, e.g. during certain developmental stages.
In Шаблон:Gli cells, the part of the Шаблон:Gli during which the Шаблон:Gli of the Шаблон:Gli takes place and replicated Шаблон:Gli are separated into two distinct nuclei. Mitosis is generally preceded by the Шаблон:Gli of Шаблон:Gli, when the cell's Шаблон:Gli, and either occurs simultaneously with or is followed by Шаблон:Gli, when the Шаблон:Gli and Шаблон:Gli are divided into two new Шаблон:Gli. Colloquially, the term "mitosis" is often used to refer to the entire process of cell division, not just the division of the nucleus.
The proportion of cells within a sample which are undergoing Шаблон:Gli at the time of observation, typically expressed as a percentage or as a value between 0 and 1. The number of cells dividing by mitosis at any given time can vary widely depending on organism, Шаблон:Gli, developmental stage, and Шаблон:Gli media, among other factors.[2]
The abnormal Шаблон:Gli between Шаблон:Gli during Шаблон:Gli (as opposed to Шаблон:Gli, where it occurs normally). Шаблон:Gli during mitosis is relatively uncommon; in the laboratory, it can be induced by exposing dividing cells to high-energy electromagnetic radiation such as X rays. As in meiosis, it can separate Шаблон:Gli alleles and thereby propagate potentially significant changes in zygosity to Шаблон:Gli, though unless it occurs very early in development this often has little or no phenotypic effect, since any phenotypic variance shown by mutant lineages arising in terminally differentiated cells is generally masked or compensated for by neighboring Шаблон:Gli cells.[2]
The process by which most animal cells undergo an overall change in shape during or preceding Шаблон:Gli, abandoning the various complex or elongated shapes characteristic of Шаблон:Gli and rapidly contracting into a rounded or spherical morphology that is more conducive to Шаблон:Gli. This phenomenon has been observed both Шаблон:Gli and Шаблон:Gli.
The presence of more than one different Шаблон:Gli level, i.e. more than one number of sets of Шаблон:Gli, in different cells of the same cellular population.[13]
The branch of biology that studies biological activity at the molecular level, in particular the various mechanisms underlying the biological processes that occur in and between Шаблон:Gli, including the structures, properties, synthesis, and modification of Шаблон:Gli such as Шаблон:Gli and Шаблон:Gli, their interactions with the chemical environment and with other biomolecules, and how these interactions explain the observations of classical biology (which in contrast studies biological systems at much larger scales).[14] Molecular biology relies largely on laboratory techniques of physics and chemistry to manipulate and measure microscopic phenomena. It is closely related to and overlaps with the fields of Шаблон:Gli, Шаблон:Gli, and Шаблон:Gli.
Any of various Шаблон:Gli methods designed to Шаблон:Gli a particular molecule, usually a Шаблон:GliШаблон:Gli or a Шаблон:Gli, many times inside the cells of a natural host. Commonly, a Шаблон:Gli fragment containing a Шаблон:Gli is Шаблон:Gli into a Шаблон:GliШаблон:Gli, which Шаблон:Gli bacterial cells are then induced to uptake in a process known as Шаблон:Gli. The bacteria, carrying the recombinant plasmid, are then allowed to proliferate naturally in Шаблон:Gli, so that each time the bacterial cells divide, the plasmids are replicated along with the rest of the bacterial genome. Any functioning gene of interest within the plasmid will be Шаблон:Gli by the bacterial cells, and thereby its Шаблон:Gli will also be cloned. The plasmids or gene products, which now exist in many copies, may then be extracted from the bacteria and purified. Molecular cloning is a fundamental tool of Шаблон:Gli employed for a wide variety of purposes, often to study Шаблон:Gli, to amplify a specific gene product, or to generate a Шаблон:Gli.
Describing cells, proteins, or molecules descended or derived from a single Шаблон:Gli (i.e. from the same genome or genetic lineage) or made in response to a single unique compound. Monoclonal Шаблон:Gli are raised against only one Шаблон:Gli or can only recognize one unique Шаблон:Gli on the same antigen. Similarly, the cells of some Шаблон:Gli and Шаблон:Gli may be described as monoclonal if they are all the asexual progeny of one original Шаблон:Gli.[2] Contrast Шаблон:Gli.
A molecule or compound which can exist individually or serve as a building block or Шаблон:Gli of a larger Шаблон:Gli aggregate known as a Шаблон:Gli.[4] Polymers form when multiple monomers of the same or similar molecular species are connected to each other by chemical bonds, either in a linear chain or a non-linear conglomeration. Examples include the individual Шаблон:Gli which form Шаблон:Gli polymers, the individual Шаблон:Gli which form Шаблон:Gli, and the individual proteins which form Шаблон:Gli.
A synthetic Шаблон:Gli connecting a short sequence of Шаблон:Gli into an artificial Шаблон:GliШаблон:Gli, used in Шаблон:Gli to Шаблон:GliШаблон:Gli by Шаблон:Gli with Шаблон:Gli sequences in naturally occurring RNA or DNA molecules, especially Шаблон:Gli, thereby inhibiting interactions with other biomolecules such as proteins and Шаблон:Gli. Morpholino oligomers are not themselves Шаблон:Gli, and neither they nor their hybrid duplexes with RNA are attacked by Шаблон:Gli; also, unlike the negatively charged Шаблон:Gli of normal nucleic acids, the synthetic backbones of Morpholinos are electrically neutral, making them less likely to interact non-selectively with a host cell's charged proteins. These properties make them useful and reliable tools for artificially generating Шаблон:Gli phenotypes in living cells.[13]
The presence of two or more populations of cells with different Шаблон:Gli in an individual organism which has developed from a single fertilized egg. A mosaic organism can result from many kinds of genetic phenomena, including Шаблон:Gli of chromosomes, Шаблон:Gli, or mutations in individual Шаблон:Gli lineages during the early development of the embryo. Mosaicism is similar to but distinct from Шаблон:Gli.
Any distinctive or recurring Шаблон:Gli of Шаблон:Gli in a Шаблон:Gli or of Шаблон:Gli in a Шаблон:Gli that is or is conjectured to be biologically significant, especially one that is reliably Шаблон:Gli by other biomolecules or which has a Шаблон:Gli that permits unique or characteristic chemical interactions such as Шаблон:Gli.[13] In nucleic acids, motifs are often short (three to ten nucleotides in length), highly Шаблон:Gli which act as recognition sites for Шаблон:Gli or RNAs involved in the regulation of Шаблон:Gli.
Any Шаблон:Gli which converts chemical energy derived from the hydrolysis of Шаблон:Gli such as Шаблон:Gli and Шаблон:Gli into mechanical work in order to effect its own locomotion, by propelling itself along a filament or through the Шаблон:Gli.[4]
Composed of more than one Шаблон:Gli. The term is used especially to describe organisms or tissues consisting of many cells descendant from the same original Шаблон:Gli which work together in an organized way, but may also describe groups of nominally single-celled organisms such as protists and bacteria which live symbiotically with each other in large colonies. Contrast Шаблон:Gli.
The integration of data from multiple "omics" technologies (e.g. data from the Шаблон:Gli, Шаблон:Gli, Шаблон:Gli, Шаблон:Gli, Шаблон:Gli, etc.) in order to study complex biological relationships, discover novel associations between biological entities, pinpoint relevant Шаблон:Gli, or build elaborate models of physiology and disease.
A locus or sequence within a Шаблон:GliШаблон:Gli which contains multiple unique Шаблон:Gli recognized by various Шаблон:Gli, which makes it possible for scientists to target the Шаблон:Gli of a DNA fragment (often a Шаблон:Gli) specifically to that locus and in the desired orientation, by Шаблон:Gli the insert and the vector with the same endonuclease(s) and then Шаблон:Gli them together via compatible restriction ends, a technique known as Шаблон:Gli.[5] Commercial plasmids designed for cloning commonly incorporate one or more multiple cloning sites.
Any physical or chemical agent that Шаблон:Gli (usually Шаблон:Gli) of an organism and thereby increases the frequency of Шаблон:Gli above natural background levels.
1. The process by which the genetic information of an organism is changed, resulting in a Шаблон:Gli. Mutagenesis may occur spontaneously or as a result of exposure to a Шаблон:Gli.
2. In Шаблон:Gli, any laboratory technique by which one or more genetic mutations are deliberately Шаблон:Gli in order to produce a Шаблон:Gli gene, regulatory element, gene product, or Шаблон:Gli so that the functions of a genetic locus, process, or product can be studied in detail.
An organism, gene product, or phenotypic Шаблон:Gli resulting from a Шаблон:Gli, of a type that would not be observed naturally in Шаблон:Gli specimens.
Any permanent change in the Шаблон:Gli of a strand of Шаблон:Gli or Шаблон:Gli, or in the Шаблон:Gli sequence of a Шаблон:Gli. Mutations play a role in both normal and abnormal biological processes; their natural occurrence is integral to the process of Шаблон:Gli. They can result from errors in Шаблон:Gli, chemical damage, exposure to high-energy radiation, or manipulations by Шаблон:Gli. Шаблон:Gli mechanisms have evolved in many organisms to correct them. By understanding the effect that a mutation has on Шаблон:Gli, it is possible to establish the function of the Шаблон:Gli or sequence in which it occurs.
One of two possible orientations by which a linear DNA fragment can be inserted into a Шаблон:Gli, specifically the one in which the Шаблон:Gli of both fragment and vector have the same orientation.[13] Contrast Шаблон:Gli.
A laboratory technique involving the use of a microscopic lance or nanopipette (typically about 100 nanometres in diameter) in the presence of an electric field in order to deliver DNA or RNA directly into a cell, often a Шаблон:Gli or early Шаблон:Gli, via an Шаблон:Gli mechanism. While submerged in a pH-buffered solution, a positive electric charge is applied to the lance, attracting negatively charged nucleic acids to its surface; the lance then penetrates the cell membrane and the electric field is reversed, applying a negative charge which repels the accumulated nucleic acids away from the lance and thus into the cell. Compare Шаблон:Gli.
The inhibition or deactivation of some biological process caused by the presence of a specific molecular entity (e.g. a Шаблон:Gli), in the absence of which the process is not inhibited and thus can proceed normally.[5] In Шаблон:Gli, for example, a repressor may bind to an Шаблон:Gli upstream from a coding sequence and prevent access by Шаблон:Gli and/or Шаблон:Gli, thereby blocking the gene's Шаблон:Gli. This is contrasted with Шаблон:Gli, in which the presence of an Шаблон:Gli is necessary to switch on transcription.[9]
The Шаблон:Gli of a Шаблон:Gli molecule in the direction opposite to the turn of the Шаблон:Gli itself (e.g. a left-handed coiling of a helix with a right-handed turn).[9] Contrast Шаблон:Gli.
A break or discontinuity in the Шаблон:Gli of one Шаблон:Gli of a Шаблон:Gli molecule, i.e. where a Шаблон:Gli is hydrolyzed but no nucleotides are removed; such a molecule is said to be nicked. A nick is a Шаблон:Gli, where despite the break the DNA molecule is not ultimately broken into multiple fragments, which contrasts with a Шаблон:Gli, where Шаблон:Gli. Nicks may be caused by Шаблон:Gli or by dedicated Шаблон:Gli known as Шаблон:Gli, which nick DNA at random or specific sites. Nicks are frequently placed by the cell as markers identifying target sites for enzyme activity, including in Шаблон:Gli, Шаблон:Gli, and Шаблон:Gli, and also to release torsional stress from Шаблон:Gli DNA molecules, making them important in manipulating Шаблон:Gli.[9]
Another name for a Шаблон:Gli, especially one that has been artificially engineered to create single-stranded breaks (i.e. Шаблон:Gli) by altering the cleavage activity of an endonuclease that normally creates double-stranded breaks, e.g. Cas9 nickase (nCas9).[15]
Any Шаблон:Gli, natural or artificial, that is not one of the 20 or 21 Шаблон:Gli encoded by the Шаблон:Gli. There are hundreds of such amino acids, many of which have biological functions and are specified by alternative codes or incorporated into proteins accidentally by Шаблон:Gli. Many of the best known naturally occurring ncAAs occur as intermediates in the metabolic pathways leading to the standard amino acids, while others have been made synthetically in the laboratory.[16]
Any segment of Шаблон:Gli that does not Шаблон:Gli a sequence that may ultimately be Шаблон:Gli and Шаблон:Gli into a Шаблон:Gli. In most organisms, only a small fraction of the genome consists of protein-coding DNA, though the proportion varies greatly between species. Some non-coding DNA may still be transcribed into functional Шаблон:Gli (as with Шаблон:Gli) or may serve important developmental or Шаблон:Gli purposes; other regions (as with so-called "Шаблон:Gli") appear to have no known biological function.
Any molecule of Шаблон:Gli that is not ultimately Шаблон:Gli into a Шаблон:Gli. The Шаблон:Gli sequence from which a functional non-coding RNA is Шаблон:Gli is often referred to as an "RNA gene". Numerous types of non-coding RNAs essential to normal genome function are produced constitutively, including Шаблон:Gli (tRNA), Шаблон:Gli (rRNA), Шаблон:Gli (miRNA), and Шаблон:Gli (siRNA); other non-coding RNAs (sometimes described as "junk RNA") have no known function and are likely the product of spurious transcription.
The failure of Шаблон:Gli or Шаблон:Gli to Шаблон:Gli properly during Шаблон:Gli. Nondisjunction results in daughter cells that are Шаблон:Gli, containing abnormal numbers of one or more specific Шаблон:Gli. It may be caused by a variety of factors.
Broadly, any Шаблон:Gli or region of a Шаблон:Gli that does not contain Шаблон:Gli, or in which repeats do not comprise a majority; or any segment of DNA exhibiting the Шаблон:Gli expected of a unique sequence.[13]
A factor which can inhibit the effects of a Шаблон:Gli (i.e. a premature stop codon) by any mechanism, usually either a mutated Шаблон:Gli which can bind the mutated stop codon or some kind of Шаблон:Gli mutation.[17]
A type of Шаблон:Gli in which the Шаблон:Gli of one Шаблон:Gli base for another results, after Шаблон:Gli and Шаблон:Gli, in an amino acid sequence that is different from that produced by the original unmutated gene. Because nonsynonymous mutations always result in a biological change in the organism, they are often subject to strong Шаблон:Gli. Contrast Шаблон:Gli.
The end of a linear chain of Шаблон:Gli (i.e. a Шаблон:Gli) that is terminated by the free amine group (Шаблон:Chem) of the first amino acid added to the chain during Шаблон:Gli. This amino acid is said to be N-terminal. By convention, sequences, domains, active sites, or any other structure positioned nearer to the N-terminus of the Шаблон:Gli or the folded Шаблон:Gli it forms relative to others are described as Шаблон:Gli. Contrast Шаблон:Gli.
Any Шаблон:Gli molecule contained within the Шаблон:Gli of a eukaryotic cell, most prominently the DNA in Шаблон:Gli. It is sometimes used interchangeably with Шаблон:Gli.
A sub-cellular barrier consisting of two concentric Шаблон:GliШаблон:Gli that surrounds the Шаблон:Gli in eukaryotic cells. The nuclear envelope is sometimes simply called the "nuclear membrane", though the structure is actually composed of two distinct membranes, an Шаблон:Gli and an Шаблон:Gli.
The principle that the nuclei of essentially all Шаблон:Gli cells of a mature multicellular organism are genetically identical to each other and to the nucleus of the Шаблон:Gli from which they descended; i.e. they all contain the same genetic information on the same chromosomes, having been replicated from the original zygotic set with extremely high fidelity. Even though all adult Шаблон:Gli have the same set of genes, cells can nonetheless differentiate into distinct Шаблон:Gli by Шаблон:Gli different subsets of these genes. Though this principle generally holds true, the reality is slightly more complex, as mutations such as Шаблон:Gli, Шаблон:Gli, Шаблон:Gli, and Шаблон:Gli as well as Шаблон:Gli, Шаблон:Gli, and various types of Шаблон:Gli can all cause different somatic lineages within the same organism to be genetically non-identical.
A fibrous network of proteins lining the inner, Шаблон:Gli surface of the Шаблон:Gli, composed of filaments similar to those that make up the Шаблон:Gli. It may function as a scaffold for the various contents of the nucleus including Шаблон:Gli and Шаблон:Gli.[3]
An Шаблон:Gli within a Шаблон:Gli which serves as a molecular signal marking the protein for Шаблон:Gli into the Шаблон:Gli, typically consisting of one or more short motifs containing positively charged amino acid residues exposed on the mature protein's surface (especially lysines and arginines). Though all proteins are Шаблон:Gli in the cytoplasm, many whose primary biological activities occur inside the nucleus (e.g. Шаблон:Gli) require nuclear localization signals identifiable by Шаблон:Gli in order to cross the Шаблон:Gli. Contrast Шаблон:Gli.
A mesh-like latticework of protein polymers and Шаблон:Gli suspended in the Шаблон:Gli in the Шаблон:Gli of eukaryotic cells, akin to the Шаблон:Gli in the Шаблон:Gli. The nuclear matrix functions as a scaffold and an anchor for large DNA molecules such as Шаблон:Gli and for the macromolecular complexes that perform essential nuclear activities such as Шаблон:Gli and Шаблон:Gli.[3]
A Шаблон:Gli of Шаблон:Gli that creates an opening in the Шаблон:Gli through which certain molecules and ions are Шаблон:Gli and thereby enter or exit the Шаблон:Gli (analogous to the Шаблон:Gli in the Шаблон:Gli). The nuclear envelope typically has thousands of pores to selectively regulate the exchange of specific materials between the Шаблон:Gli and the Шаблон:Gli, including Шаблон:Gli, which are transcribed in the nucleus but must be translated in the cytoplasm, as well as Шаблон:Gli, which are synthesized in the cytoplasm but must return to the nucleus to serve their functions.[4][3]
Any Шаблон:Gli molecule located within a cell's Шаблон:Gli, whether associated with chromosomes or existing freely in the nucleoplasm, including Шаблон:Gli (snRNA), Шаблон:Gli (eRNA), and all newly transcribed Шаблон:Gli, Шаблон:Gli or Шаблон:Gli, prior to their export to the cytosol (hnRNA).
The mechanisms by which molecules cross the Шаблон:Gli surrounding a cell's nucleus. Though small molecules and ions can cross the membrane freely, the entry and exit of larger molecules is tightly regulated by Шаблон:Gli, so that most Шаблон:Gli such as RNAs and proteins require association with transport factors in order to be Шаблон:Gli across.
Any of a class of Шаблон:Gli capable of cleaving Шаблон:Gli connecting adjacent Шаблон:Gli in a nucleic acid molecule (the opposite of a Шаблон:Gli). Nucleases may Шаблон:GliШаблон:Gli or Шаблон:Gli strands of a duplex molecule, and may cleave randomly or at specific recognition sequences. They are ubiquitous and imperative for normal cellular function, and are also widely employed in laboratory techniques.
A long, Шаблон:GliШаблон:Gli made up of smaller Шаблон:Gli called Шаблон:Gli which are chemically linked to one another in a chain. Two specific types of nucleic acid, Шаблон:Gli and Шаблон:Gli, are common to all living organisms, serving to encode the genetic information governing the construction, development, and ordinary processes of all biological systems. This information, contained within the order or Шаблон:Gli, is Шаблон:Gli into Шаблон:Gli, which direct all of the chemical reactions necessary for life.
The precise order of consecutively linked Шаблон:Gli in a Шаблон:Gli molecule such as Шаблон:Gli or Шаблон:Gli. Long sequences of nucleotides are the principal means by which biological systems store genetic information, and therefore the accurate Шаблон:Gli, Шаблон:Gli, and Шаблон:Gli of such sequences is of the utmost importance, lest the information be lost or corrupted. Nucleic acid sequences may be equivalently referred to as sequences of nucleotides, Шаблон:Gli, Шаблон:Gli, or, in Шаблон:Gli, Шаблон:Gli, and they correspond directly to sequences of Шаблон:Gli and Шаблон:Gli.
An irregularly shaped region which contains most or all of the genetic material in prokaryotic cells such as bacteria, but is not enclosed by a Шаблон:Gli as in eukaryotes.
The basic structural subunit of Шаблон:Gli used in Шаблон:Gli nuclear DNA such as chromosomes, consisting of a Шаблон:GliШаблон:Gli proteins around which Шаблон:Gli is wrapped in a manner akin to thread wound around a spool. The technical definition of a nucleosome includes a segment of DNA about 146 base pairs in length which makes 1.67 left-handed turns as it coils around the histone core, as well as a stretch of Шаблон:Gli (generally 38–80 bp) connecting it to an adjacent core particle, though the term is often used to refer to the core particle alone. Long series of nucleosomes are further condensed by association with histone H1 into higher-order structures such as Шаблон:Gli and ultimately Шаблон:GliШаблон:Gli. Because the histone–DNA interaction limits access to the DNA molecule by other proteins and RNAs, the precise positioning of nucleosomes along the DNA sequence plays a fundamental role in controlling whether or not genes are Шаблон:Gli and Шаблон:Gli, and hence mechanisms for moving and ejecting nucleosomes have evolved as a means of Шаблон:Gli the expression of particular loci.
A region of a genome or chromosome in which long segments of DNA are bound by few or no Шаблон:Gli, and thus exposed to manipulation by other proteins and molecules, especially implying that the region is Шаблон:Gli active.
The Шаблон:Gli (blue) are the five specific Шаблон:Gli canonically used in DNA and RNA. A nucleobase bonded to a Шаблон:Gli sugar (either Шаблон:Gli or Шаблон:Gli; yellow) is known as a Шаблон:Gli (yellow + blue). A nucleoside bonded to a single Шаблон:Gli (red) is known as a nucleoside monophosphate (NMP) or a Шаблон:Gli (red + yellow + blue). When not incorporated into a nucleic acid chain, free nucleosides can bind multiple phosphate groups: two phosphates yields a Шаблон:Gli (NDP), and three yields a Шаблон:Gli (NTP).
A large spherical or lobular Шаблон:Gli surrounded by a Шаблон:Gli which functions as the main storage compartment for the genetic material of eukaryotic cells, including the DNA comprising Шаблон:Gli, as well as the site of RNA synthesis during Шаблон:Gli. The vast majority of eukaryotic cells have a single nucleus, though some cells may have Шаблон:Gli, either temporarily or permanently, and in some organisms there exist certain cell types (e.g. mammalian Шаблон:Gli) which lose their nuclei upon reaching maturity, effectively becoming Шаблон:Gli. The nucleus is one of the defining features of eukaryotes; the cells of prokaryotes such as bacteria lack nuclei entirely.[2]
Шаблон:Gli of Шаблон:Gli which are synthesized discontinuously by Шаблон:Gli and later linked together by Шаблон:Gli to create the Шаблон:Gli during Шаблон:Gli. Okazaki fragments are the consequence of the unidirectionality of DNA polymerase, which only works in the 5' to 3' direction.
A suffix used to describe any of the diverse fields of study that conduct rigorous, systematic analyses of any of the "omes", e.g. the Шаблон:Gli, Шаблон:Gli, Шаблон:Gli, Шаблон:Gli, etc.,[5] each of which represents the totality of a specific class of biological content that has been or could hypothetically be isolated from an individual cell, population of cells, organism, species, or some other particular context. Thus Шаблон:Gli is the field of study which analyzes the totality of genes in a genome, Шаблон:Gli studies the complete set of all of the proteins in a proteome, etc. The term may also be used to refer to all of these fields collectively.
The hypothesis that there exists a large class of Шаблон:Gli in which each particular gene directs the synthesis of one particular Шаблон:Gli or Шаблон:Gli.[13] Historically it was thought that all genes and proteins might follow this rule by definition, but it is now known that many proteins are composites of different polypeptides and therefore the product of multiple genes, and also that some genes do not encode polypeptides at all but instead produce Шаблон:Gli, which are never translated.
A functional unit of Шаблон:Gli consisting of a cluster of neighboring Шаблон:Gli which are collectively under the control of a single Шаблон:Gli, along with one or more adjacent Шаблон:Gli sequences such as Шаблон:Gli. The set of genes is Шаблон:Gli together, resulting in a single Шаблон:GliШаблон:Gli molecule encoding multiple distinct polypeptides which may then be Шаблон:Gli together or undergo Шаблон:Gli to create multiple mRNAs which are translated independently; the result is that the genes contained in the operon are either expressed together or not at all. Regulatory proteins, including Шаблон:Gli and Шаблон:Gli, usually bind specifically to the regulatory sequences of a given operon; by some definitions, the genes that code for these regulatory proteins are also considered part of the operon.
A spatially distinct compartment or subunit within a Шаблон:Gli which has a specialized function. Organelles occur in both prokaryotic and eukaryotic cells. In the latter they are often separated from the Шаблон:Gli by being enclosed with their own Шаблон:GliШаблон:Gli (whence the term Шаблон:Gli), though organelles may also be functionally specific areas or structures without a surrounding membrane; some cellular structures which exist partially or entirely outside of the cell membrane, such as Шаблон:Gli and Шаблон:Gli, are also referred to as organelles. There are numerous types of organelles with a wide variety of functions, including the various compartments of the Шаблон:Gli (e.g. the Шаблон:Gli, Шаблон:Gli, and Шаблон:Gli), Шаблон:Gli, Шаблон:Gli, Шаблон:Gli, Шаблон:Gli, and Шаблон:Gli, among others. Many organelles are unique to particular cell types or species.
A particular location within a DNA molecule at which Шаблон:Gli is initiated. Origins are usually defined by the presence of a particular replicator sequence or by specific chromatin patterns.
Physiological dysfunction caused by a sudden change in the concentration of dissolved solutes in the Шаблон:Gli environment surrounding a cell, which provokes the rapid movement of water across the Шаблон:Gli by Шаблон:Gli, either into or out of the cell. In a severely Шаблон:Gli environment, where extracellular solute concentrations are extremely high, osmotic pressure may force large quantities of water to move out of the cell (Шаблон:Gli), leading to its desiccation; this may also have the effect of inhibiting transport of solutes into the cell, thus denying it the substrates necessary to sustain normal cellular activities. In a severely Шаблон:Gli environment, where extracellular solute concentrations are much lower than intracellular concentrations, water is forced to move into the cell (Шаблон:Gli), causing it to swell in size and potentially burst, or triggering Шаблон:Gli.
An abnormally high level of Шаблон:Gli which results in an excessive number of copies of one or more Шаблон:Gli. Overexpression produces a pronounced gene-related Шаблон:Gli.[19][20]
The process by which cells use chemical energy obtained by the oxidation of nutrients to power the production of Шаблон:Gli (ATP). Oxidative phosphorylation couples two related processes: in the Шаблон:Gli, a series of enzyme-catalyzed redox reactions transfers electrons from energetic donors such as Шаблон:Gli and Шаблон:Gli through various intermediates and ultimately to a terminal electron acceptor such as molecular oxygen (Шаблон:Chem); the energy liberated by these reactions is simultaneously used in Шаблон:Gli to move protons (Шаблон:Chem) across a membrane and against their concentration gradient, generating an electrochemical potential which powers Шаблон:Gli, an enzyme that catalyzes the Шаблон:Gli of Шаблон:Gli into ATP. In eukaryotes, both of these processes are carried out by proteins embedded in the membranes of Шаблон:Gli and Шаблон:Gli; in prokaryotes, they occur in the cell membrane.
The flow of oxygen from environmental sources (e.g. the air in the atmosphere) to the Шаблон:Gli of a cell, where oxygen atoms participate in biochemical reactions that result in the oxidation of energy-rich substrates such as Шаблон:Gli in a process known as Шаблон:Gli.
A class of regulatory proteins encoded by the TP53 gene in vertebrates which Шаблон:Gli and Шаблон:Gli in order to protect the genome from mutation and block progression through the Шаблон:Gli if DNA damage does occur.[4] It is mutated in more than 50% of human cancers, indicating it plays a crucial role in preventing cancer formation.
The transfer of substances across an Шаблон:Gli by passing through the Шаблон:Gli space between cells, in contrast to Шаблон:Gli, where substances travel through cells by crossing the Шаблон:Gli cytoplasm.
Describing or relating to a class of agonistШаблон:Gli molecules produced and secreted by regulatory cells into the extracellular environment and then transported by passive diffusion to target cells other than those which produced them. The term may refer to the molecules themselves, sometimes called paramones, to the cells that produce them, or to signaling pathways which rely on them.[5] Compare Шаблон:Gli, Шаблон:Gli, and Шаблон:Gli.
An idiotope, i.e. the specific site or region within an Шаблон:Gli that recognizes and binds to a particular Шаблон:Gli or Шаблон:Gli.[21] The uniqueness of a paratope allows it to bind to only one epitope with very high affinity. At the end of each arm of the Y-shaped antibody is an identical paratope, and each paratope comprises a total of six Шаблон:Gli (three from each of the Шаблон:Gli and Шаблон:Gli) which protrude from a series of antiparallel Шаблон:Gli in the antibody's higher structure.[22] The term is also sometimes used to refer to the specific site on a Шаблон:Gli molecule which defines the ligand's specificity for other molecules such as Шаблон:Gli.[3]
The movement of a solute across a Шаблон:Gli by traveling down an electrochemical or concentration gradient, using only the energy stored in the gradient and not any energy from external sources.[3] Contrast Шаблон:Gli.
A phenomenon observed in Шаблон:Gli cells, including animal tissues and many microorganisms such as yeast, whereby the presence of oxygen in the environment inhibits the cell's use of ethanol Шаблон:Gli pathways to generate energy, and drives the cell to instead make use of the available oxygen in Шаблон:Gli;[23] or more generally the observed decrease in the rate of Шаблон:Gli or of lactate production in cells exposed to oxygenated air.[5]
Any Шаблон:Gli containing five carbon atoms. The compounds Шаблон:Gli and Шаблон:Gli are both pentose sugars, which, in the form of cyclic five-membered rings, serve as the central structural components of the Шаблон:Gli and Шаблон:Gli that make up Шаблон:Gli and Шаблон:Gli, respectively.
A glycoconjugate complex of interwoven peptides and polysaccharides that is a primary constituent of the Шаблон:Gli in all bacteria and archaea, consisting of strands of glycosaminoglycansШаблон:Gli by short Шаблон:Gli (usually 4–10 residues[3]) to form a rigid lattice of indefinite size.[5] The proportion of the cell wall that is peptidoglycan varies widely by strain and is often used to aid strain identification: the higher peptidoglycan content of the cell walls of Gram-positive bacteria causes them to Шаблон:Gli a darker color than Gram-negative bacteria.
Any of a class of Шаблон:Gli which attach only temporarily to the Шаблон:Gli, either by penetrating the Шаблон:Gli or by attaching to Шаблон:Gli which are permanently embedded within the membrane.[24] The ability to reversibly interact with membranes makes peripheral membrane proteins important in many different roles, commonly as regulatory Шаблон:Gli of Шаблон:Gli and Шаблон:Gli. Their Шаблон:Gli often undergo rearrangement, dissociation, or Шаблон:Gli when they interact with the membrane, resulting in the activation of their biological activity.[25] In Шаблон:Gli, peripheral membrane proteins are typically more water-soluble and much easier to isolate from the membrane than Шаблон:Gli.
1. The tendency of a Шаблон:Gli to continue moving in the same direction as previously; that is, even in isotropic environments, there inevitably still exists an inherent bias by which, from instant to instant, cells are more likely not to change direction than to change direction. Averaged over long periods of time, however, this bias is less obvious and cell movements are better described as a Шаблон:Gli.[3]
2. The ability of some viruses to remain present and viable in cells, organisms, or populations for very long periods of time by any of a variety of strategies, including retroviral integration and immune suppression, often in a latent form which replicates very slowly or not at all.[3]
A shallow, transparent plastic or glass dish, usually circular and covered with a lid, which is widely used in biology laboratories to hold solid or liquid Шаблон:Gli for the purpose of Шаблон:Gli. They are particularly useful for Шаблон:Gli, where they provide a flat, sterile surface conducive to colony formation from which scientists can easily isolate and identify individual colonies.
A Шаблон:Gli with a genome encoding a mobile Шаблон:Gli that can be Шаблон:Gli by co-infection of the host cell with a Шаблон:Gli. Phagemids are useful as vectors for library production.[3]
Any cell capable of Шаблон:Gli, especially any of various cell types of the immune system which engulf and ingest harmful foreign molecules, bacteria, and dead or dying cells, including Шаблон:Gli and Шаблон:Gli.[3]
The process by which foreign cells, molecules, and small particulate matter are engulfed and ingested via Шаблон:Gli by specialized cells known as Шаблон:Gli (a class which includes Шаблон:Gli and neutrophils).[4]
A large, intracellular, membrane-bound Шаблон:Gli formed as a result of Шаблон:Gli and containing whatever previously extracellular material was engulfed during that process.[4]
The complete set of Шаблон:Gli that are or can be expressed by a Шаблон:Gli, cell, tissue, organism, or species; the sum of all of its manifest chemical, morphological, and behavioral characteristics or traits.
A delay in the Шаблон:GliШаблон:Gli of a genetic Шаблон:Gli owing to the time required for the manifestation of changes in the affected biochemical pathways.[9]
The composite of the observable morphological, physiological, and behavioral Шаблон:Gli of an organism that result from the Шаблон:Gli of the organism's Шаблон:Gli as well as the influence of environmental factors and the interactions between the two.
A type of phenotypic plasticity in which a cell rapidly undergoes major changes to its morphology and/or function, usually via Шаблон:Gli modifications, allowing it to quickly switch back and forth between disparate phenotypes in response to changes in the local microenvironment.
Any chemical species or functional group derived from phosphoric acid (Шаблон:Chem) by the removal of one or more protons (Шаблон:Chem); the completely ionized form, Шаблон:Chem, consists of a single, central phosphorus atom covalently bonded to four oxygen atoms via three single bonds and one double bond. Phosphates are abundant and ubiquitous in biological systems, where they occur either as free anions in solution, known as inorganic phosphates and symbolized Pi, or bonded to organic molecules via ester bonds. The huge diversity of organophosphate compounds includes all Шаблон:Gli, whose phosphate groups are linked by Шаблон:Gli to form the Шаблон:Gli of Шаблон:Gli such as Шаблон:Gli and Шаблон:Gli, and the high-energy diphosphate and triphosphate substituents of individual nucleotides such as Шаблон:Gli and Шаблон:Gli serve as essential energy carriers in all cells. Шаблон:Gli are major components of most Шаблон:Gli. Enzymes known as Шаблон:Gli and Шаблон:Gli catalyze the Шаблон:Gli and Шаблон:Gli of phosphate groups to and from these and other biomolecules.
The linear chain of alternating Шаблон:Gli and sugar compounds that results from the linking of consecutive Шаблон:Gli in the same Шаблон:Gli of a Шаблон:Gli molecule, and which serves as the structural framework of the nucleic acid. Each individual strand is held together by a repeating series of Шаблон:Gli connecting each Шаблон:Gli to the Шаблон:Gli or Шаблон:Gli sugars of two adjacent nucleotides. These bonds are created by Шаблон:Gli and broken by Шаблон:Gli.
A defining element of nucleic acid structure is the linear chain of alternating Шаблон:Gli (orange) and Шаблон:Gli (yellow) known as the Шаблон:Gli, which acts as a scaffold to which Шаблон:Gli are attached. The phosphorus atom of each phosphate group forms two Шаблон:Gli to specific carbon atoms within the pentose sugars—Шаблон:Gli in RNA and Шаблон:Gli in DNA—of two adjacent nucleosides.
A pair of ester bonds linking a Шаблон:Gli molecule with the two Шаблон:Gli rings of consecutive Шаблон:Gli on the same strand of a Шаблон:Gli. Each phosphate forms a covalent bond with the Шаблон:Gli of one pentose and the Шаблон:Gli of the adjacent pentose; the repeated series of such bonds that holds together the long chain of nucleotides comprising Шаблон:Gli and Шаблон:Gli molecules is known as the Шаблон:Gli.
Any of a subclass of Шаблон:Gli consisting of a central alcohol (usually glycerol) covalently bonded to three functional groups: a negatively charged Шаблон:Gli group, and two long Шаблон:Gli chains. This arrangement results in a highly amphipathic molecule which in aqueous solutions tends to aggregate with similar molecules in a lamellar or micellar conformation with the Шаблон:Gli phosphate "heads" oriented outward, exposing them to the solution, and the Шаблон:Gli fatty acid "tails" oriented inward, minimizing their interactions with water and other polar compounds. Phospholipids are the major structural Шаблон:Gli in almost all biological Шаблон:Gli except the membranes of some plant cells and Шаблон:Gli, where Шаблон:Gli dominate instead.[3]
The attachment of a Шаблон:Gli ion, Шаблон:Chem, to another molecule or ion or to a Шаблон:Gli by covalent bonding. Phosphorylation and the inverse reaction, Шаблон:Gli, are essential steps in numerous biochemical pathways, including in the production of Шаблон:Gli (ATP) (as in Шаблон:Gli); in the metabolism of Шаблон:Gli and the synthesis of Шаблон:Gli; and in the Шаблон:Gli of amino acid residues in many proteins. Шаблон:Gli which catalyze phosphorylation reactions are known as Шаблон:Gli; those that catalyze dephosphorylation are known as Шаблон:Gli.
A form of Шаблон:Gli in which liquid and suspended solids from the Шаблон:Gli environment are captured in inward Шаблон:Gli of the Шаблон:Gli which then "bud off" into enclosed Шаблон:Gli in the Шаблон:Gli. The contents of these vesicles are then passed to organelles such as Шаблон:Gli by fusion of the vesicular and organellar membranes. Pinocytosis is the predominant form of endocytosis occurring in most cells, such that the term is often used interchangeably with endocytosis as a whole.[5]
The number of Шаблон:Gli contained within a single complete turn of the Шаблон:GliШаблон:Gli,[13] used as a measure of the "tightness" or density of the helix's spiral.
The development of resistance to toxins or antibiotics which is enabled by the Шаблон:Gli of Шаблон:Gli encoded within small, independently replicating DNA molecules known as Шаблон:Gli. This process occurs naturally via mechanisms such as Шаблон:Gli, but is also a common aspect of Шаблон:Gli methods such as Шаблон:Gli.
Any of a class of Шаблон:Gli found in the cells of some eukaryotes such as plants and algae which are hypothesized to have evolved from endosymbioticcyanobacteria; examples include Шаблон:Gli, chromoplasts, and leucoplasts. Plastids retain their own Шаблон:Gli which replicate independently of the host cell's genome. Many contain photosynthetic pigments which allow them to perform Шаблон:Gli, while others have been retained for their ability to synthesize unique chemical compounds.
1. Variability in the size, shape, or Шаблон:Gli of cells and/or their nuclei, particularly as observed in Шаблон:Gli and Шаблон:Gli, where morphological variation is frequently Шаблон:Gli of a cellular abnormality such as disease or Шаблон:Gli.
2. In microbiology, the ability of some microorganisms such as certain bacteria and viruses to alter their morphology, metabolism, or mode of reproduction in response to changes in their environment.
The tendency of cells within a Шаблон:Gli to migrate in the direction of the local highest tension or maximal principal stress, exerting minimal shear stress on neighboring cells and thereby propagating the tension across many intercellular junctions and causing the cells to exhibit a sort of collective migration.[27]
The number of complete sets of Шаблон:Gli in a cell, and hence the number of possible Шаблон:Gli present within the cell at any given Шаблон:Gli locus.
A cell's Шаблон:Gli level is defined by the number of copies it has of each specific chromosome: if the cell has two copies of each of three distinct chromosomes, it is said to be Шаблон:Gli (2N).
A Шаблон:Gli consisting of a chain of repeated Шаблон:Gli residues, 40–250 nucleotides in length, attached to the Шаблон:Gli of nearly all mature eukaryotic Шаблон:Gli transcripts (those of Шаблон:Gli being a notable exception).[5]
The addition of a series of multiple Шаблон:GliШаблон:Gli, known as a Шаблон:Gli, to the Шаблон:Gli of a Шаблон:Gli, typically a Шаблон:Gli. Primary transcripts are first cleaved 10–30 nucleotides downstream of a highly conserved Шаблон:Font sequence, then the poly(A) tail is generated from the chaining of multiple Шаблон:Gli molecules through the action of polynucleotide adenylyltransferase.[5] A class of Шаблон:Gli, polyadenylation serves different purposes in different cell types and organisms. In eukaryotes, the addition of a poly(A) tail is an important step in the processing of a raw transcript into a mature mRNA, ready for export to the cytoplasm where Шаблон:Gli occurs; in many bacteria, polyadenylation has the opposite function, instead promoting the RNA's degradation.
Describing cells, proteins, or molecules descended or derived from more than one Шаблон:Gli (i.e. from more than one genome or genetic lineage) or made in response to more than one unique stimulus. Шаблон:Gli are often described as polyclonal if they have been produced or raised against multiple distinct Шаблон:Gli or multiple variants of the same antigen, such that they can recognize more than one unique Шаблон:Gli.[2] Contrast Шаблон:Gli.
A Шаблон:Gli composed of multiple repeating Шаблон:Gli or Шаблон:Gli; a chain or aggregation of many individual molecules of the same compound or class of compound.[2] The formation of polymers is known as Шаблон:Gli and generally only occurs when Шаблон:Gli sites are present and the concentration of monomers is sufficiently high.[3] Many of the major classes of Шаблон:Gli are polymers, including Шаблон:Gli and Шаблон:Gli.
Any of a wide variety of molecular biology methods involving the rapid production of millions or billions of copies of a specific Шаблон:Gli, allowing scientists to selectively Шаблон:Gli fragments of a very small sample to a quantity large enough to study in detail. In its simplest form, PCR generally involves the incubation of a target DNA sample of known or unknown sequence with a reaction mixture consisting of Шаблон:GliШаблон:Gli, a heat-stable Шаблон:Gli, and free Шаблон:Gli (dNTPs), all of which are supplied in excess. This mixture is then alternately heated and cooled to pre-determined temperatures for pre-determined lengths of time according to a specified pattern which is repeated for many cycles, typically in a Шаблон:Gli which automatically controls the required temperature variations. In each cycle, the most basic of which includes a Шаблон:Gli phase, Шаблон:Gli phase, and Шаблон:Gli phase, the copies synthesized in the previous cycle are used as Шаблон:Gli for synthesis in the next cycle, causing a chain reaction that results in the exponential growth of the total number of copies in the reaction mixture. Amplification by PCR has become a standard technique in virtually all molecular biology laboratories.
A diagram of the exponential amplification of a specific DNA sequence via the Шаблон:Gli (PCR)
The formation of a Шаблон:Gli from its constituent Шаблон:Gli; the chemical reaction or series of reactions by which monomeric Шаблон:Gli are covalently linked together into a polymeric chain or branching aggregate; e.g. the polymerization of a Шаблон:Gli chain by linking consecutive Шаблон:Gli, a reaction catalyzed by a Шаблон:Gli enzyme.
1. In genetics, the regular and simultaneous existence of two or more discontinuous Шаблон:Gli or genotypes in the same population where the frequency of each allele is greater than can be explained by recurrent mutation alone, typically occurring in more than 1 percent of the population's individuals.[3] An example is the different human blood types (A, B, AB, and O).[5]
2. In chemistry, the existence of the same substance in two or more different crystalline forms.[5]
(of a cell or organism) Having more than two homologous copies of each Шаблон:Gli; i.e. any Шаблон:Gli level that is greater than Шаблон:Gli. Polyploidy may occur as a normal condition of chromosomes in certain cells or even entire organisms, or it may result from errors in Шаблон:Gli or mutations causing the duplication of the entire chromosome set.
The condition of a cell or organism having at least one more copy of a particular Шаблон:Gli than is normal for its Шаблон:Gli level, e.g. a Шаблон:Gli organism with three copies of a given chromosome is said to show Шаблон:Gli. Every polysomy is a type of Шаблон:Gli.
Any effect on the Шаблон:Gli or functionality of a Шаблон:Gli or sequence that is a consequence of its location or position within a Шаблон:Gli or other DNA molecule. A sequence's precise location relative to other sequences and structures tends to strongly influence its activity and other properties, because different Шаблон:Gli on the same molecule can have substantially different Шаблон:Gli and physical/chemical environments, which may also change over time. For example, the Шаблон:Gli of a gene located very close to a Шаблон:Gli, Шаблон:Gli, or Шаблон:Gli is often Шаблон:Gli or entirely prevented because the proteins that make up these structures block access to the DNA by Шаблон:Gli, while the same gene is transcribed at a much higher rate when located in Шаблон:Gli. Proximity to Шаблон:Gli, Шаблон:Gli, and other Шаблон:Gli, as well as to regions of frequent Шаблон:Gli by Шаблон:Gli, can also directly affect expression; being located near the end of a chromosomal arm or to common Шаблон:Gli points may affect when Шаблон:Gli occurs and the likelihood of Шаблон:Gli. Position effects are a major focus of research in the field of Шаблон:Gli.
A strategy for identifying and Шаблон:Gli a Шаблон:Gli based on knowledge of its Шаблон:Gli or position alone and with little or no information about its Шаблон:Gli or function, in contrast to Шаблон:Gli. This method usually begins by comparing the genomes of individuals expressing a Шаблон:Gli of unknown provenance (often a Шаблон:Gli) and identifying Шаблон:Gli shared between them. Regions defined by markers flanking one or more Шаблон:Gli are cloned, and the genes located between the markers can then be identified by any of a variety of means, e.g. by Шаблон:Gli the region and looking for Шаблон:Gli, by comparing the sequence and expression patterns of the region in Шаблон:Gli and Шаблон:Gli individuals, or by testing the ability of the putative gene to Шаблон:Gli a mutant phenotype.[13]
The initiation, activation, or enhancement of some biological process by the presence of a specific molecular entity (e.g. an Шаблон:Gli or Шаблон:Gli), in the absence of which the process cannot proceed or is otherwise diminished.[5] In Шаблон:Gli, for example, the binding of an activating molecule such as a Шаблон:Gli to a Шаблон:Gli may recruit Шаблон:Gli to a coding sequence, thereby causing it to be Шаблон:Gli. Contrast Шаблон:Gli.
The Шаблон:Gli of a Шаблон:Gli molecule in the same direction as the turn of the Шаблон:Gli itself (e.g. a right-handed coiling of a helix with a right-handed turn).[9] Contrast Шаблон:Gli.
A partially differentiated or intermediate Шаблон:Gli with the ability to further differentiate into only one Шаблон:Gli; i.e. a Шаблон:Gli stem cell that is the immediate parent cell from which fully differentiated cell types divide. The term "precursor cell" is sometimes used interchangeably with Шаблон:Gli, though this term may also be considered technically distinct.
The unprocessed, single-stranded Шаблон:Gli molecule produced by the Шаблон:Gli of a Шаблон:Gli sequence as it exists before Шаблон:Gli such as Шаблон:Gli convert it into a mature RNA product such as an Шаблон:Gli, Шаблон:Gli, or Шаблон:Gli. A precursor mRNA or pre-mRNA, for example, is a primary transcript which, after processing, becomes a mature mRNA ready for Шаблон:Gli.
A short, Шаблон:GliШаблон:Gli, typically 5–100 bases in length, which "primes" or initiates nucleic acid synthesis by Шаблон:Gli to a complementary sequence on a Шаблон:Gli and thereby providing an existing Шаблон:Gli from which a Шаблон:Gli can Шаблон:Gli the new strand. Natural systems exclusively use Шаблон:Gli primers to initiate Шаблон:Gli and some forms of prokaryotic Шаблон:Gli, whereas the Шаблон:Gli syntheses performed in many laboratory techniques such as Шаблон:Gli often use Шаблон:Gli primers. In modern laboratories, primers are carefully designed, often in "forward" and "reverse" pairs, to complement specific and unique sequences in target DNA molecules, with consideration given to their Шаблон:Gli and Шаблон:Gli temperatures, and then purchased from commercial suppliers which create oligonucleotides on demand by Шаблон:Gli.
An inactive precursor of a Шаблон:Gli or Шаблон:Gli that is converted into the active form by some Шаблон:Gli, such as by cleaving a specific peptide sequence from the precursor or by attaching other molecules to specific amino acid residues. The names of protein precursors are often prefixed with pro-, as in proinsulin. Enzyme precursors may be called Шаблон:Gli.
Any reagent used to make a single measurement in a biochemical assay such as a gene expression experiment. Molecules which have a specific affinity for one or more other molecules may be used to probe for the presence of those other molecules in samples of unknown composition. Probes are often Шаблон:Gli or otherwise used as Шаблон:Gli to indicate whether or not a specific chemical reaction is taking place. See also Шаблон:Gli.
A collection of two or more Шаблон:Gli designed to measure a single molecular species, such as a collection of Шаблон:Gli designed to Шаблон:Gli to various parts of the Шаблон:Gli transcripts generated from a single gene.
An alternative definition of a Шаблон:Gli which emphasizes the contribution of non-DNA factors to the process by which the information encoded in a Шаблон:Gli results in the synthesis of a Шаблон:Gli.
A sequence or region of DNA, usually 100–1,000 base pairs long, which Шаблон:Gli the Шаблон:Gli of one or more associated Шаблон:Gli by containing binding sites for Шаблон:Gli which recruit Шаблон:Gli to the sequence and initiate Шаблон:Gli. Promoters are typically located immediately Шаблон:Gli of the genes they regulate, near to and often including the Шаблон:Gli.
Any of a class of Шаблон:Gli which catalyze Шаблон:Gli, i.e. the decomposition of proteins into smaller polypeptides or individual amino acids, by cleaving Шаблон:Gli via hydrolysis. Proteases are ubiquitous components of numerous Шаблон:Gli, and therefore it is often necessary to inhibit them in order for laboratory techniques involving protein activity to be effective.
A large Шаблон:Gli of Шаблон:Gli enzymes that selectively degrades intracellular proteins which have been Шаблон:Gli for degradation by Шаблон:Gli. Proteasomes play important roles in the timing and onset of cellular processes through the signal-mediated Шаблон:Gli of certain enzymes and regulatory proteins; they also contribute to the stress response by removing abnormal proteins and to the immune response by generating Шаблон:Gli peptides.[5]
A Шаблон:GliШаблон:Gli composed of one or more Шаблон:Gli of Шаблон:Gli linked by Шаблон:Gli. Proteins are the three-dimensional structures created when these chains Шаблон:Gli into specific higher-order arrangements following Шаблон:Gli, and it is this folded structure which determines a protein's chemical activity and hence its biological function. Ubiquitous and fundamental in all living organisms, proteins are the primary means by which the activities of life are performed, participating in the vast majority of the biochemical reactions that occur inside and outside of cells. They are often classified according to the type(s) of reaction(s) they facilitate or catalyze, by the chemical substrate(s) they act upon, or by their functional role in cellular activity; e.g. as Шаблон:Gli, Шаблон:Gli, Шаблон:Gli, Шаблон:Gli, or links within Шаблон:Gli.
An assembly or aggregate of multiple Шаблон:Gli held together by intermolecular forces, especially one with a particular biological function. Complexes may include many of the same protein or all different proteins. Numerous cellular activities, including Шаблон:Gli, Шаблон:Gli, and Шаблон:Gli, rely on protein complexes.[4]
The physical process by which the linear chains of amino acids (i.e. Шаблон:Gli) synthesized during Шаблон:Gli are changed from random coils into stable, orderly, three-dimensional shapes (i.e. Шаблон:Gli) by assuming a higher-order structure or Шаблон:Gli which permits the protein to be biologically functional, known as its Шаблон:Gli. Folding is the consequence of amino acid residues participating in intermolecular electrostatic interactions with each other and with their surroundings, including other molecules, and so is strongly influenced by the particularities of the local chemical environment. The time it takes to properly fold a protein can vary greatly, but the process often begins while chain synthesis is still ongoing. Some chains may have Шаблон:Gli or Шаблон:Gli which Шаблон:Gli and remain unfolded across a wide range of chemical conditions. Having the correct three-dimensional structure is essential for proper protein function, and misfolded proteins are generally biologically inactive, though mutant folds can occasionally modify functionality in useful ways.
Any of a class of enzymes which Шаблон:Gli proteins by catalyzing the transfer of a Шаблон:Gli from Шаблон:Gli to an amino acid residue and often causing a functionally relevant Шаблон:Gli as a result. The great majority of protein kinases phosphorylate the hydroxyl side chains of either serine, threonine, or tyrosine, though other types also exist.[3] Separate classes of Шаблон:Gli phosphorylate non-protein molecules such as lipids and carbohydrates.
The set of biological mechanisms by which Шаблон:Gli are directed and transported to appropriate destinations within or outside of the cell. Proteins must often be routed into the interior of Шаблон:Gli, embedded Шаблон:Gli, or Шаблон:Gli into the extracellular environment in order to serve their functions, and information contained in the protein itself instructs this delivery process.[28] In eukaryotic cells, an expansive network of organelles and Шаблон:Gli is specialized to facilitate protein sorting, including the Шаблон:Gli and the Шаблон:Gli.
A Шаблон:Gli containing a Шаблон:Gli which can be transcribed and translated to produce a Шаблон:Gli, as opposed to an Шаблон:Gli, which produces Шаблон:Gli transcripts that are not translated into proteins but instead have functions in and of themselves.
Any of the 20 canonical Шаблон:Gli which are encoded by the Шаблон:Gli and incorporated into Шаблон:Gli and ultimately Шаблон:Gli during Шаблон:Gli. The term may also be inclusive of an additional two amino acids encoded by non-standard Шаблон:Gli which can be incorporated by special translation mechanisms.
Any heavily Шаблон:GliШаблон:Gli, i.e. a core polypeptide with one or more covalently attached glycosaminoglycan chains. Proteoglycans are therefore considered a subclass of Шаблон:Gli in which the carbohydrate units are long, linear Шаблон:Gli polymers containing amino sugars[29] and generally bearing a net negative charge under physiological conditions due to the presence of sulfates and uronic acid groups. They are a major component of the Шаблон:Gli between animal cells, where they form large hydrated complexes commonly employed in connective tissues such as cartilage.
The decomposition of Шаблон:Gli into their component Шаблон:Gli or individual Шаблон:Gli by Шаблон:Gli the Шаблон:Gli linking the amino acids together via hydrolysis. Proteolysis is an important reaction used not only for degrading and inactivating proteins but sometimes also to activate them by removing amino acid residues which inhibit their activity.[3] It is usually catalyzed by Шаблон:Gli known as Шаблон:Gli.
The entire set of Шаблон:Gli that is or can be Шаблон:Gli by a particular Шаблон:Gli, cell, tissue, or species at a particular time (such as during a single lifespan or during a specific developmental stage) or under particular conditions (such as when compromised by a certain disease).
The study of the Шаблон:Gli of a particular genome, cell, or organism, i.e. the sum total of all of the Шаблон:Gli produced from it by Шаблон:Gli. Proteomics technologies allow scientists to Шаблон:Gli and identify proteins and Шаблон:Gli and determine which ones are most and least abundant at a given time or under a given experimental condition.
Any molecular subunit from which a larger Шаблон:GliШаблон:Gli is built, including those subunits which are not strictly Шаблон:Gli and can themselves be divided into subunits. For example, a Шаблон:Gli of tubulin proteins is the protomer for Шаблон:Gli assembly.[3]
The biological contents enclosed within a Шаблон:Gli space, variously referring to the Шаблон:Gli, or the cytoplasm and Шаблон:Gli considered collectively, and sometimes exclusive of Шаблон:Gli.
A plant, fungal, or bacterial cell which has had its Шаблон:Gli removed by mechanical, chemical, or enzymatic means; or the complete contents (the Шаблон:Gli) of an intact cell excluding the cell wall.
The Шаблон:Gli of substances from a cell, organelle, or tissue in a regular, rhythmic, pulse-like pattern. Many Шаблон:Gli molecules such as Шаблон:Gli and Шаблон:Gli are released in this manner in order to maintain Шаблон:Gli or to sensitize target cells by stimulating their production of Шаблон:Gli.
A specific Шаблон:Gli suspected to be a functional Шаблон:Gli based on the identification of its Шаблон:Gli. The gene is said to be "putative" in the sense that no function has yet been described for its Шаблон:Gli.
A Шаблон:Gli in which there is little or no active cell growth or replication but in which the cells nonetheless continue to survive, as observed with some Шаблон:Gli cultures.[2]
A popular description of the path followed by a Шаблон:Gli or particle when there is no bias in movement, i.e. when the direction of movement at any given instant is not influenced by the direction of movement in the preceding instant. The essential randomness of cell movement in a uniform environment is only apparent over long periods of time, however; in the short term, cells can and do exhibit Шаблон:Gli.[3]
A way of dividing the Шаблон:Gli in a Шаблон:Gli or Шаблон:Gli molecule into a series of consecutive, non-overlapping groups of three nucleotides, known as Шаблон:Gli, which is how the sequence is interpreted or "read" by Шаблон:Gli during Шаблон:Gli. In Шаблон:Gli, each triplet is referred to as a Шаблон:Gli and corresponds to a particular Шаблон:Gli to be added to the nascent peptide chain during translation. In general, only one reading frame (the so-called Шаблон:Gli) in a given sequence encodes a functional protein, though there are exceptions. A Шаблон:Gli results in a shift in the normal reading frame which affects all downstream codons and usually results in a completely different and senseless amino acid sequence.
The measurement and manipulation of the rate of Шаблон:Gli of Шаблон:Gli strands of Шаблон:Gli, generally by heating and denaturing a Шаблон:Gli molecule into Шаблон:Gli and then observing their rehybridization at a cooler temperature. Because the Шаблон:GliШаблон:Font+Шаблон:Font requires more energy to anneal than the base pair Шаблон:Font+Шаблон:Font, the rate of reannealing between two strands depends partly on their Шаблон:Gli, and it is therefore possible to predict or estimate the sequence of the duplex molecule by the time it takes to fully hybridize. Reassociation kinetics is studied with Шаблон:Gli: fragments reannealing at low C0t values tend to have highly Шаблон:Gli, while higher C0t values imply more unique sequences.[13]
A Шаблон:Gli which initiates a cellular response to an external stimulus or Шаблон:Gli by binding a specific Шаблон:Gli, often a dedicated signaling molecule. Numerous types of receptors exist which serve an enormous variety of functions. Шаблон:Gli, such as those that bind acetylcholine and insulin, are embedded within the Шаблон:Gli with their Шаблон:Gli exposed to the extracellular space; intracellular receptors, including many Шаблон:Gli receptors, are located in the cytoplasm, where they bind ligands that have diffused across the membrane and into the cell.[4]
A type of Шаблон:Gli by which there is a reciprocal exchange of chromosome segments between two or more non-Шаблон:GliШаблон:Gli. When the exchange of material is evenly balanced, reciprocal translocations are usually harmless.
A Шаблон:Gli between chromosome 4 and chromosome 20
A specific Шаблон:Gli or Шаблон:Gli, either of nucleotides in a nucleic acid molecule or of amino acids in a protein, that is "recognized" or identified by another protein in order to direct the protein's activity to a specific molecule or location. Recognition motifs may consist of a simple consecutive sequence within a single molecule or may involve multiple non-consecutive motifs, e.g. amino acids in separate parts of the same polypeptide which are brought into juxtaposition by the Шаблон:Gli created during Шаблон:Gli. Recognition sites often help to distinguish the nucleic acid or protein bearing the motif from other similar molecules and thereby identify it as a valid target for some biochemical activity, or to specify a locus or subregion within the larger macromolecule at which the activity is to occur. In this sense recognition sites are critical for properly localizing proteins to their biochemical targets. A protein's recognition site is often but not necessarily the same as its Шаблон:Gli or Шаблон:Gli.[5]
Any Шаблон:Gli molecule in which laboratory methods of Шаблон:Gli have brought together genetic material from multiple sources, thereby creating a Шаблон:Gli that would not otherwise be found in a naturally occurring genome. Because DNA molecules from all organisms share the same basic chemical structure and properties, DNA sequences from any species, or even sequences created de novo by Шаблон:Gli, may be incorporated into recombinant DNA molecules. Recombinant DNA technology is widely used in Шаблон:Gli.
The smallest unit of a DNA molecule capable of undergoing Шаблон:Gli, i.e. a pair of consecutive nucleotides, adjacent to each other in Шаблон:Gli.[13]
A group of non-contiguous Шаблон:Gli which are Шаблон:Gli as a unit, generally by virtue of having their Шаблон:Gli controlled by the same regulatory element or set of elements, e.g. the same Шаблон:Gli or Шаблон:Gli. The term is most commonly used with prokaryotes, where a regulon may consist of genes from multiple Шаблон:Gli.
Any pattern of Шаблон:Gli within a Шаблон:Gli which occurs in multiple copies in the same nucleic acid molecule such as a chromosome or within a genome. Repeated sequences are classified according to their length, structure, location, mode of replication, or evolutionary origin. They may be any length, but are often short Шаблон:Gli of less than 100 bases; they may be Шаблон:Gli or Шаблон:Gli, and may occur in Шаблон:Gli with the copies immediately adjacent to each other or Шаблон:Gli with non-repeated sequences. Significant fractions of most eukaryotic genomes consist of Шаблон:Gli, much of it retroviral in origin, though repeats may also result from errors in normal cellular processes, as with Шаблон:Gli during Шаблон:Gli or Шаблон:Gli. Because so many genetic mechanisms depend on the Шаблон:Gli or Шаблон:Gli of locally unique sequences, sequences containing or adjacent to repeats are particularly prone to errors in replication and transcription by Шаблон:Gli, or to forming problematic Шаблон:Gli, and thus repeats are often unstable in the sense that the number of copies tends to expand or diminish stochastically with each round of replication, causing great Шаблон:Gli even between different cells in the same organism. When repeats occur within Шаблон:Gli or Шаблон:Gli, these properties often result in aberrant expression and lead to disease. Repeats are also essential for normal genome function in other contexts, as with Шаблон:Gli and Шаблон:Gli, which consist largely of repetitive sequences.
1. The process by which certain biological molecules, notably the Шаблон:GliШаблон:Gli and Шаблон:Gli, produce copies of themselves.
2. A technique used to estimate technical and biological variation in experiments for statistical analysis of Шаблон:Gli data. Replicates may be technical replicates, such as dye swaps or repeated array Шаблон:Gli, or biological replicates, biological samples from separate experiments which are used to test the effects of the same experimental treatment.
The eye-shaped structure that forms when a pair of Шаблон:Gli, each growing away from the Шаблон:Gli, separates the strands of the double helix during Шаблон:Gli.
The point at which the paired strands of a Шаблон:Gli molecule are separated by Шаблон:Gli during Шаблон:Gli, breaking the hydrogen bonds between the complementary strands and thereby forming a structure with two branching single strands of DNA. Once unpaired, these strands serve as Шаблон:Gli from which Шаблон:Gli synthesizes the Шаблон:Gli and Шаблон:Gli. As replication proceeds, helicase moves along the DNA and continues to separate the strands, causing the replication fork to move as well.[3] A pair of replication forks forms when helicases work in opposite directions from a single Шаблон:Gli, creating a Шаблон:Gli.
The speed at which Шаблон:Gli are incorporated into an elongating chain by Шаблон:Gli during Шаблон:Gli; or more generally the speed at which any chromosome, genome, cell, or organism makes a complete, independently functional copy of itself.
The entire complex of molecular machinery that carries out the process of Шаблон:Gli, including all proteins, nucleic acids, and other molecules which participate at an active Шаблон:Gli.
In Шаблон:Gli, a gene which when properly expressed encodes a gene product that is easily detected or visualized with biochemical assays (e.g. green fluorescent protein, β-galactosidase, chloramphenicol O-acetyltransferase, etc.), allowing researchers to use its expression in order to study the functions and properties of associated Шаблон:Gli. Reporters are commonly Шаблон:Gli into plasmid Шаблон:Gli in proximity to putative Шаблон:Gli, Шаблон:Gli, or Шаблон:Gli, which are then mutated in order to precisely identify the specific Шаблон:Gli within these sequences that are necessary for expression. In the broadest sense, reporters may also include things like molecular Шаблон:Gli, fluorescent Шаблон:Gli, and Шаблон:Gli which render their conjugated molecules conspicuous or able to be purified; or they may be used similarly to Шаблон:Gli, to distinguish cells that express a given product from those that do not, so that researchers can easily identify mutants of interest or verify the success of an experimental treatment or laboratory procedure.[5]
The restoration of a defective cell or tissue to a healthy or normal condition,[13] or the Шаблон:Gli or recovery of a mutant gene to its normal functionality, especially in the context of experimental genetics, where an experiment (e.g. a drug, Шаблон:Gli, or gene transfer) resulting in such a restoration is said to rescue the normal Шаблон:Gli.
Any short sequence of DNA that serves some function related to the activity of a protein or other biomolecule, especially a sequence within a Шаблон:Gli region that is able to bind specific Шаблон:Gli in order to Шаблон:GliШаблон:Gli of specific genes.
A Шаблон:Gli containing twice the expected number of chromosomes owing to an error in cell division, especially an unreduced, Шаблон:Gli product of Шаблон:Gli resulting from the failure of the first or second meiotic division.
An Шаблон:Gli or Шаблон:GliШаблон:Gli that recognizes and cleaves a nucleic acid molecule into Шаблон:Gli at or near specific recognition sequences known as Шаблон:Gli by breaking the Шаблон:Gli of the nucleic acid Шаблон:Gli. Restriction enzymes are naturally occurring in many organisms, but are also routinely used for artificial modification of DNA in laboratory techniques such as Шаблон:Gli.
Variability within a population of organisms observed in the size of the Шаблон:Gli produced when Шаблон:Gli (or any particular DNA molecule) is Шаблон:Gli by one or more Шаблон:Gli. This variability results from a corresponding Шаблон:Gli in the locations of restriction sites within the molecule(s) due to slight differences in nucleotide sequence between individuals. RFLP is frequently exploited in the laboratory to construct physical Шаблон:Gli, to identify the specific Шаблон:Gli occupied by a particular gene, and to detect genetic differences between closely related individuals or determine that different samples originated from the same individual. Analysis of restriction fragments can also reveal the presence of a mutation that may itself cause disease or be closely linked to one that does.[5]
The use of type II Шаблон:Gli to cleave DNA molecules at specific Шаблон:Gli in order to produce characteristic patterns of Шаблон:Gli which can be resolved by size using Шаблон:Gli. Шаблон:Gli DNA molecules such as Шаблон:Gli or Шаблон:Gli with one or multiple restriction enzymes makes it possible to deduce from the sizes of the resulting fragments the order or arrangement of the restriction sites within the molecule and the distances between them, and thus to construct reliable Шаблон:Gli with restriction sites effectively serving as Шаблон:Gli.[5]
A short, specific Шаблон:Gli of nucleotides (typically 4 to 8 bases in length) that is reliably recognized by a particular Шаблон:Gli. Because restriction enzymes usually bind as Шаблон:Gli, restriction sites are generally Шаблон:Gli spanning both strands of a Шаблон:Gli molecule. Restriction Шаблон:Gli cleave the Шаблон:Gli between two nucleotides within the recognized sequence itself, while other types of restriction enzymes make their cuts at one end of the sequence or at a nearby sequence.
A double-stranded DNA molecule containing the sequence Шаблон:Font and its palindromic complement functions as a Шаблон:Gli for the bacterial enzyme EcoRI, which recognizes and Шаблон:Gli it in the manner shown here, by breaking phosphodiester bonds in the backbones of both strands and leaving behind Шаблон:Gli at the ends of each of the now separate molecules.
A Шаблон:Gli or other DNA sequence which has arisen in a genome by the stable Шаблон:Gli of the genetic material of a retrovirus, e.g. by the Шаблон:Gli of viral RNA and the subsequent Шаблон:Gli of the resulting DNA fragments into the host cell's Шаблон:Gli.[5] These endogenous viral elements can then be replicated along with the host's own genes and thus persist indefinitely in the host genome, and in many cases retain the ability to produce functional viral proteins from this latent state, by which they may continue to copy, Шаблон:Gli, and/or Шаблон:Gli themselves.
An experimental approach in Шаблон:Gli in which a researcher starts with a known Шаблон:Gli and attempts to determine its function or its effect on phenotype by any of a variety of laboratory techniques, commonly by deliberately mutating the gene's DNA sequence or by Шаблон:Gli or Шаблон:Gli its Шаблон:Gli and then Шаблон:Gli the mutant organisms for changes in phenotype. When the gene of interest is the only one in the genome whose expression has been manipulated, any observed phenotypic changes are assumed to be influenced by it. This is the opposite of Шаблон:Gli, in which a known phenotype is linked to one or more unknown genes.
The synthesis of a Шаблон:Gli molecule from an Шаблон:GliШаблон:Gli, i.e. the opposite of ordinary Шаблон:Gli. This process, mediated by an enzyme known as a Шаблон:Gli, is used by many viruses to Шаблон:Gli their genomes, as well as by Шаблон:Gli and in some eukaryotic cell types.
An enzyme which catalyzes the formation of Шаблон:Gli via the reductivedehydroxylation of Шаблон:Gli, specifically by removing the 2' hydroxyl group from the Шаблон:Gli ring of Шаблон:Gli (rNDPs). RNR plays a critical role in regulating the overall rate of DNA synthesis such that the ratio of DNA to cell mass is kept constant during cell division and Шаблон:Gli.
A Шаблон:Gli sugar which, as D-ribose in its Шаблон:Gli ring form, is one of three primary components of the Шаблон:Gli from which Шаблон:Gli (RNA) molecules are built. Ribose differs from its structural analog Шаблон:Gli only at the 2' carbon, where ribose has an attached hydroxyl group that deoxyribose lacks.
A DNA sequence that codes for Шаблон:Gli (rRNA). In many eukaryotic genomes, rDNA occupies large, highly conserved regions of multiple chromosomes and is rich in both Шаблон:Gli and Шаблон:Gli.
A type of Шаблон:Gli which is the primary constituent of Шаблон:Gli, binding to ribosomal proteins to form the Шаблон:Gli and Шаблон:Gli. It is ribosomal RNA which enables ribosomes to perform protein synthesis by working as a Шаблон:Gli that catalyzes the set of reactions comprising Шаблон:Gli. Ribosomal RNA is transcribed from the corresponding Шаблон:Gli (rDNA) and is the most abundant class of RNA in most cells, bearing responsibility for the translation of all encoded proteins despite never being translated itself.
A macromolecular complex made of both RNA and protein which serves as the site of protein synthesis by Шаблон:Gli. Ribosomes have two Шаблон:Gli, each of which consists of one or more strands of Шаблон:Gli bound to various ribosomal proteins: the Шаблон:Gli, which reads the messages encoded in Шаблон:Gli molecules, and the Шаблон:Gli, which links Шаблон:Gli in sequence to form a Шаблон:Gli chain. Ribosomes are essential and ubiquitous in all cell types and are used by all known forms of life.
An Шаблон:Gli molecule with enzymatic activity,[4] i.e. one that is capable of catalyzing one or more specific biochemical reactions, similar to Шаблон:GliШаблон:Gli. Ribozymes function in numerous capacities, including in Шаблон:Gli as part of the Шаблон:GliШаблон:Gli.
Any of a class of Шаблон:GliШаблон:Gli that synthesize Шаблон:Gli molecules from a Шаблон:Gli template. RNA polymerases are essential for Шаблон:Gli and are found in all living organisms and many viruses. They build long single-stranded polymers called Шаблон:Gli by adding Шаблон:Gli one at a time in the Шаблон:Gli-to-Шаблон:Gli direction, relying on the Шаблон:Gli provided by the Шаблон:Gli strand to transcribe the nucleotide sequence faithfully. Unlike Шаблон:Gli, RNA polymerases notably do not require oligonucleotide Шаблон:Gli to initiate synthesis; i.e. they are capable of synthesizing RNA molecules Шаблон:Gli.
A Шаблон:Gli complex which works to Шаблон:Gli endogenous and exogenous genes by participating in various Шаблон:Gli pathways at the transcriptional and translational levels. RISC can bind both Шаблон:Gli and Шаблон:Gli fragments and then cleave them or use them as guides to target complementary mRNAs for degradation.
A type of Шаблон:Gli by which Шаблон:Gli at or near the Шаблон:Gli of two Шаблон:GliШаблон:Gli cause a reciprocal exchange of segments that gives rise to one large Шаблон:Gli chromosome (composed of the Шаблон:Gli) and one extremely small chromosome (composed of the Шаблон:Gli), the latter of which is often subsequently lost from the cell with little effect because it contains very few genes. The resulting Шаблон:Gli shows one fewer than the expected total number of chromosomes, because two previously distinct chromosomes have essentially fused together. Шаблон:Gli of Robertsonian translocations are generally not associated with any phenotypic abnormalities, but do have an increased risk of generating meiotically unbalanced Шаблон:Gli.
A type of membrane in the Шаблон:Gli with numerous Шаблон:Gli conspicuously attached to its surface, in contrast to the Шаблон:Gli which lacks ribosomes. The rough ER serves as the site of protein synthesis for the majority of the cell's secreted and transmembrane proteins, as well as the site of synthesis of membrane lipids. It may be continuous with the smooth ER or exist separately.[3]
A method of Шаблон:Gli based on the in vitroШаблон:Gli of a DNA Шаблон:Gli sequence, during which fluorochrome-labeled, chain-terminating dideoxynucleotides are randomly incorporated in the elongating strand; the resulting fragments are then sorted by size with Шаблон:Gli, and the particular fluorochrome terminating each of the size-sorted fragments is detected by laser chromatography, thus revealing the Шаблон:Gli of the original DNA template through the order of the fluorochrome labels as one reads from small-sized fragments to large-sized fragments. Though Sanger sequencing has been replaced in some contexts by Шаблон:Gli methods, it remains widely used for its ability to produce relatively long sequence reads (500+ Шаблон:Gli) and its very low error rate.
An Шаблон:Gli nucleic acid Шаблон:Gli reaction in which one polynucleotide component (either Шаблон:Gli or Шаблон:Gli) is supplied in great excess relative to the other, causing all complementary sequences in the other polynucleotide to pair with the excess sequences and form hybrid Шаблон:Gli molecules.[13]
A molecule or compound (often a protein) that is caused to accumulate in an Шаблон:Gli cell by the action of a Шаблон:Gli, growth factor, or other agonist and thereby brings about the action of that agonist on the cell. Second messengers are therefore critical mediators of a diverse variety of Шаблон:Gli pathways, including the synthesis of Шаблон:Gli by adenylate cyclase and of Шаблон:Gli by guanylate cyclase, the opening of Шаблон:Gli, and the Шаблон:Gli of proteins by serine/threonine-specific or tyrosine-specific Шаблон:Gli.[5]
The arrangement or Шаблон:Gli of a Шаблон:Gli's Шаблон:Gli into higher-order, locally organized structures, primarily via hydrogen bonding between non-adjacent amino acid residues, in particular Шаблон:Gli and Шаблон:Gli; or the arrangement of double-stranded Шаблон:Gli chains into the shape of a Шаблон:Gli stabilized by hydrogen bonds between the complementary bases.[5]
A Шаблон:Gli or other genetic material whose Шаблон:Gli in cultured cells confers a selective advantage in the culture environment, causing cells expressing the gene to have one or more traits suitable for artificial selection. Selectable markers are widely used in the laboratory as a type of Шаблон:Gli, usually to indicate the success of a procedure meant to introduce exogenous DNA into a host cell such as Шаблон:Gli or Шаблон:Gli. A common example is an Шаблон:Gli which is transformed into competent bacterial cells cultured on a medium containing the particular antibiotic, such that only those cells which have successfully taken up and expressed the gene are able to survive and grow into colonies.
Any genetic material (e.g. a Шаблон:Gli or any other DNA sequence) which can enhance its own Шаблон:Gli and/or transmission into subsequent generations at the expense of other genes in the genome, even if doing so has no positive effect or even a net negative effect on the Шаблон:Gli of the genome as a whole. Selfish elements usually work by producing self-acting Шаблон:Gli which repeatedly Шаблон:Gli their own Шаблон:Gli into other parts of the genome, independently of normal Шаблон:Gli (as with Шаблон:Gli); by facilitating the uneven swapping of chromosome segments during Шаблон:Gli events (as with Шаблон:Gli); or by disrupting the normally equal redistribution of replicated material during Шаблон:Gli or Шаблон:Gli such that the probability that the selfish element is present in a given Шаблон:Gli is greater than the normal 50 percent (as with Шаблон:Gli).
The standard mode of Шаблон:Gli that occurs in all living cells, in which each of the two parental Шаблон:Gli of the original Шаблон:Gli molecule are used as Шаблон:Gli, with Шаблон:Gli replicating each strand separately and simultaneously in Шаблон:Gli directions. The result is that each of the two double-stranded daughter molecules is composed of one of the original parental strands and one newly synthesized complementary strand, such that each daughter molecule conserves the precise sequence of information (indeed the very same atoms) from one-half of the original molecule. Contrast Шаблон:Gli and Шаблон:Gli.
Three different modes of Шаблон:Gli. In Шаблон:Gli, each of the two daughter molecules is built from one of the original parental strands and one newly synthesized strand. In Шаблон:Gli, the original parent molecule remains intact while the replicated molecule is composed of two newly synthesized strands. In Шаблон:Gli, each of the daughter molecules is an uneven mix of old and new, with some segments consisting of the two parental strands and others consisting of two newly synthesized strands. Only semiconservative replication occurs naturally.
A distinction made between the individual Шаблон:Gli of a Шаблон:Gli molecule in order to easily and specifically identify each strand. The two Шаблон:Gli strands are distinguished as sense and antisense or, equivalently, the Шаблон:Gli and the Шаблон:Gli. It is the antisense/template strand which is actually used as the template for Шаблон:Gli; the sense/coding strand merely resembles the sequence of Шаблон:Gli on the RNA transcript, which makes it possible to determine from the DNA sequence alone the expected amino acid sequence of any protein Шаблон:Gli from the RNA transcript. Which strand is which is relative only to a particular RNA transcript and not to the entire DNA molecule; that is, either strand can function as the sense/coding or antisense/template strand.
Any Шаблон:Gli that specifies an Шаблон:Gli, as opposed to a Шаблон:Gli, which does not specify any particular amino acid but instead signals the end of translation.
A Шаблон:Gli depicts the statistical frequency with which each nucleobase (or amino acid) occurs within a given Шаблон:Gli. Each position in the sequence is represented by a vertical stack of letters; the total height of the stack indicates the degree of Шаблон:Gli at that position between all of the aligned sequences, and the height of each individual letter in the stack indicates the proportion of the aligned sequences having that nucleobase at that position. A single very large letter filling most of the stack indicates that most or all of the aligned sequences have that particular nucleobase at that position.
The determination of the order or Шаблон:Gli of Шаблон:Gli in a Шаблон:Gli molecule, or of Шаблон:Gli in a Шаблон:Gli, by any means. Sequences are usually written as a linear string of letters which conveniently summarizes much of the atomic-level structure of the molecule.
The presence of a particular Шаблон:Gli or DNA sequence on a Шаблон:Gli (in mammals either the Шаблон:Gli or the Шаблон:Gli) rather than on an Шаблон:Gli; these genes are said to be sex-linked. Expression of sex-linked genes varies by organism depending on the mechanism of sex determination and the types of sex chromosomes present, but the associated Шаблон:Gli often exclusively appear in either the homogametic or heterogametic sex.[2]
In condensed Шаблон:Gli where the positioning of the Шаблон:Gli creates two segments or "arms" of unequal length, the shorter of the two arms of a Шаблон:Gli. Contrast Шаблон:Gli.
A method of Шаблон:Gli in which Шаблон:Gli is randomly fragmented (e.g. by Шаблон:Gli or Шаблон:Gli), Шаблон:Gli into Шаблон:Gli vectors, and then Шаблон:Gli using Шаблон:Gli that anneal to flanking sequences in the plasmids. Computer software is used to Шаблон:Gli via overlapping Шаблон:Gli,[5] allowing scientists to deduce the relative genomic locations of each fragment and thereby assemble a complete genome.
Any sequence of Шаблон:Gli, usually 15–30 residues in length, that functions as a molecular signal directing the Шаблон:Gli and transport of the Шаблон:Gli bearing it to a Шаблон:Gli within a cell or organelle. Signal peptides are commonly located close to either the Шаблон:Gli or Шаблон:Gli ends of Шаблон:Gli or recently synthesized polypeptides, especially those destined for secretion from the cell or integration into a membrane, and are typically cleaved off by a dedicated Шаблон:Gli when their polypeptide reaches the Шаблон:Gli.[5] Similar but distinct varieties of protein targeting are accomplished with Шаблон:Gli and Шаблон:GliШаблон:Gli.
The process by which a chemical, electrical, or mechanical signal is converted into a cellular response, or the transmission or propagation of such a signal through a cell as a series of molecular events known as a Шаблон:Gli. For example, the extracellular interaction of a Шаблон:Gli, growth factor, or some other chemical agonist with a specific Шаблон:Gli can trigger a Шаблон:Gli of sequential biochemical reactions which propagate through the cell membrane and into the cytoplasm, provoking the synthesis of Шаблон:Gli and leading to amplification of the signal or activation of other pathways. Other modes of transduction involve agonists which diffuse across the membrane freely, eliciting intracellular changes without amplification, or rapid shifts in Шаблон:Gli which transmit electrical impulses, such as those that cause the axons of neural cells to release neurotransmitters at synapses.[5]
The total or near-total loss of Шаблон:Gli of a particular Шаблон:Gli or DNA sequence by any mechanism, natural or artificial, whether before, during, or after Шаблон:Gli or Шаблон:Gli, which completely prevents the normal Шаблон:Gli from being produced and thereby deprives the cell of its ordinary function. Gene silencing may occur via natural Шаблон:Gli mechanisms such as condensation of the relevant segment of DNA into a transcriptionally inactive, Шаблон:Gli state, in which case the term is more or less equivalent to Шаблон:Gli; genes are also commonly silenced artificially for research purposes by using techniques such as Шаблон:Gli (e.g. by Шаблон:Gli) or Шаблон:Gli (by Шаблон:Gli the gene from the genome entirely). See also Шаблон:Gli.
A type of Шаблон:Gli which does not have an observable effect on the organism's Шаблон:Gli. Though the term "silent mutation" is often used interchangeably with Шаблон:Gli, synonymous mutations are not always silent, nor vice versa. Шаблон:Gli which result in a different Шаблон:Gli but one with similar functionality (e.g. leucine instead of isoleucine) are also often classified as silent, since such mutations usually do not significantly affect protein function.
Any Шаблон:Gli of a single Шаблон:Gli which occurs at a specific position within a Шаблон:Gli and with measurable frequency within a population; for example, at a specific base position in a DNA sequence, the majority of the individuals in a population may have a Шаблон:Gli (Шаблон:Font), while in a minority of individuals, the same position may be occupied by an Шаблон:Gli (Шаблон:Font). SNPs are usually defined with respect to a "standard" reference genome; an individual human genome differs from the reference human genome at an average of 4 to 5 million positions, most of which consist of SNPs and short Шаблон:Gli. See also Шаблон:Gli.
Any Шаблон:Gli molecule that consists of a single nucleotide polymer or Шаблон:Gli, as opposed to a pair of complementary strands held together by hydrogen bonds (Шаблон:Gli). In most circumstances, DNA is more stable and more common in double-stranded form, but high temperatures, low concentrations of dissolved salts, and very high or low pH can cause double-stranded molecules to decompose into two single-stranded molecules in a Шаблон:Gli process known as Шаблон:Gli; this reaction is exploited by naturally occurring enzymes such as those involved in Шаблон:Gli as well as by laboratory techniques such as Шаблон:Gli.
A pair of identical copies (Шаблон:Gli) produced as the result of the Шаблон:Gli of a Шаблон:Gli, particularly when both copies are joined together by a common Шаблон:Gli; the pair of sister chromatids is called a dyad. The two sister chromatids are ultimately separated from each other into two different cells during Шаблон:Gli or Шаблон:Gli.
A class of small Шаблон:Gli molecules engineered so as to change conformation conditionally in response to cognate molecular inputs, often with the goal of controlling Шаблон:Gli pathways Шаблон:Gli or Шаблон:Gli.
A class of small Шаблон:Gli molecules, approximately 100–300 nucleotides in length and rich in Шаблон:Gli residues, found in association with specific proteins as part of Шаблон:Gli complexes known as snRNPs within Шаблон:Gli and Шаблон:Gli of the eukaryotic nucleus.[5] SnRNPs assemble into larger complexes known as Шаблон:Gli which play important roles in the Шаблон:Gli of Шаблон:Gli transcripts (Шаблон:Gli) before they are exported to the cytoplasm.
A class of small Шаблон:Gli molecules whose primary function is to direct the Шаблон:Gli of other RNAs, mainly Шаблон:Gli (tRNA), Шаблон:Gli (snRNA), and especially Шаблон:Gli (rRNA) as a part of Шаблон:Gli synthesis in the Шаблон:Gli. SnoRNAs contain Шаблон:Gli sequences that complement sequences within these target RNAs and guide Шаблон:Gli complexes to them, which can then catalyze specific nucleoside modifications, typically Шаблон:Gli or Шаблон:Gli.
A subclass of Шаблон:Gli, originally described in nematodes, which regulate the timing of developmental events by binding to complementary sequences in the Шаблон:Gli of Шаблон:Gli and inhibiting their Шаблон:Gli. In contrast to Шаблон:Gli, which serve similar purposes, stRNAs bind to their target mRNAs after the initiation of translation and without affecting mRNA stability, which makes it possible for the target mRNAs to resume translation at a later time.
Any of a family of small Шаблон:Gli, each approximately 100 amino acids, which are covalently Шаблон:Gli to and removed from charged residues of other proteins in a form of Шаблон:Gli known as Шаблон:Gli, thereby functioning as a Шаблон:Gli in a manner resembling Шаблон:Gli.
A type of membrane in the Шаблон:Gli that lacks Шаблон:Gli on its surface, thus visibly contrasting with the Шаблон:Gli. Smooth ER tends to be tubular rather than sheet-like, and may form an extension of the rough ER or exist separately. It is especially abundant in cells concerned with Шаблон:Gli metabolism.[3]
Any biological cell forming the body of an organism, or, in multicellular organisms, any cell other than a Шаблон:Gli, Шаблон:Gli, or undifferentiated Шаблон:Gli. Somatic cells are theoretically distinct from cells of the Шаблон:Gli, meaning the Шаблон:Gli they have undergone can never be transmitted to the organism's descendants, though in practice exceptions do exist.
The application of sound energy at ultrasonic frequencies in order to agitate particles in a chemical or biological sample. Intense acoustic vibrations produce pressure waves and cavitations that propagate through a liquid medium, thereby converting the sound energy to mechanical energy which can disperse solutes, disrupt intermolecular interactions, and break covalent bonds. At various amplitudes sonication can be used to increase the permeability of cell or nuclear Шаблон:Gli, a technique known as Шаблон:Gli, or to Шаблон:Gli and release their contents for isolation and extraction. It has a wide variety of applications in industry and research, including creating nanoparticles such as Шаблон:Gli, shearing DNA and proteins into smaller fragments, degassing liquids, and ultrasonic cleaning.
Any sequence or region of Шаблон:Gli separating neighboring Шаблон:Gli, whether Шаблон:Gli or not. The term is used in particular to refer to the non-coding regions between the many repeated copies of the Шаблон:Gli genes.[9] See also Шаблон:Gli.
The Шаблон:Gli of one or more genes only within a specific anatomical region or tissue, often in response to a Шаблон:Gli signal. The boundary between the jurisdictions of two spatially restricted genes may generate a sharp Шаблон:Gli gradient there, as with striping patterns.
The Шаблон:Gli structure that forms during Шаблон:Gli in eukaryotic cells, consisting of a network of long, flexible Шаблон:Gli extending from each pole of the Шаблон:Gli and attaching to Шаблон:Gli at the centromeres of Шаблон:Gli or Шаблон:Gli near the cell equator. As the microtubules shorten, they pull the chromosomes apart, separating them into different Шаблон:Gli. Proper formation of this apparatus is critical in both Шаблон:Gli and Шаблон:Gli, where it is respectively referred to as the mitotic spindle and meiotic spindle.
A large Шаблон:Gli complex found primarily in the nucleus of eukaryotic cells, composed of multiple small nuclear ribonucleoproteins (snRNPs) which are themselves composed of Шаблон:Gli (snRNAs) and a variety of snRNP-specific proteins. Spliceosomes assemble at the junctions between Шаблон:Gli and Шаблон:Gli within Шаблон:Gli and catalyze the Шаблон:Gli of the introns and the Шаблон:Gli of the flanking exons in a form of post-transcriptional processing known as Шаблон:Gli.[30]
Any natural or artificial process involving the Шаблон:Gli of oligonucleotide sequences from nucleic acid molecules (either DNA or RNA) or of peptide sequences from proteins and the subsequent Шаблон:Gli of the flanking fragments into a single continuous molecule lacking the excised sequence. Шаблон:Gli in particular is an important form of Шаблон:Gli whereby Шаблон:Gli are removed from Шаблон:Gli transcripts and the Шаблон:Gli rejoined (and sometimes Шаблон:Gli) to create mature mRNAs; a Шаблон:Gli also occurs with the removal of Шаблон:Gli and the rejoining of Шаблон:Gli in the Шаблон:Gli of certain proteins. The term may also refer more generally to artificial techniques for creating Шаблон:Gli sequences in Шаблон:Gli.[5]
The Шаблон:Gli used by the vast majority of living organisms for Шаблон:GliШаблон:Gli into Шаблон:Gli. In this system, of the 64 possible permutations of Шаблон:Gli that can be made from the four Шаблон:Gli, 61 code for one of the 20 Шаблон:Gli, and the remaining three code for Шаблон:Gli. For example, the codon Шаблон:Font codes for the amino acid glutamine and the codon Шаблон:Gli is a stop codon. The standard genetic code is described as Шаблон:Gli or redundant because some amino acids can be coded for by more than one different codon.
The Шаблон:Gli specifies a set of 20 different Шаблон:Gli from triplet arrangements of the four different Шаблон:GliШаблон:Gli (Шаблон:Gli, Шаблон:Gli, Шаблон:Gli, and Шаблон:Gli). To read this chart, choose one of the four letters in the innermost ring and then move outward, adding two more letters to complete a Шаблон:Gli triplet: a total of 64 unique codons can be made this way, 61 of which signal the addition of one of the 20 amino acids (identified by single-letter abbreviation as well as by full name and chemical structure) to a nascent Шаблон:Gli chain, while the remaining three codons are Шаблон:Gli signalling the termination of translation. Also indicated are some of the chemical properties of the amino acids and the various ways in which they can be modified.
A branch of genetics concerned with the development of statistical methods for drawing inferences from genetic data. The theories and methodologies of statistical genetics often support research in Шаблон:Gli, Шаблон:Gli, and Шаблон:Gli.
Any biological cell which has not yet Шаблон:Gli into a specialized cell type and which can divide through Шаблон:Gli to produce more undifferentiated stem cells.
A term used to describe the end of a Шаблон:Gli molecule where one Шаблон:Gli is longer than the other by one or more Шаблон:Gli, creating a single-stranded "overhang" of unpaired bases, in contrast to a so-called Шаблон:Gli, where no such overhang exists because the terminal nucleobases on each strand are Шаблон:Gli with each other. Blunt ends and sticky ends are relevant when Шаблон:Gli linear DNA molecules, e.g. in Шаблон:Gli, because many Шаблон:Gli cleave the phosphate backbone in a way that leaves behind terminal overhangs in the digested fragments. These sticky-ended molecules ligate much more readily with other sticky-ended molecules having Шаблон:Gli overhangs, allowing scientists to ensure that specific DNA fragments are ligated together in specific places.
An individual chain of Шаблон:Gli comprising a Шаблон:Gli polymer, existing either independently (in which case the nucleic acid molecule is said to be Шаблон:Gli) or Шаблон:Gli in a Шаблон:Gli with another, separate strand (in which case it is said to be Шаблон:Gli).
The effect of conditions such as temperature and pH upon the degree of Шаблон:Gli that is required for a Шаблон:Gli reaction to occur between two single-stranded nucleic acid molecules. In the most stringent conditions, only exact complements can successfully hybridize; as stringency decreases, an increasing number of Шаблон:Gli can be tolerated between the two hybridizing strands.[18]
Any Шаблон:Gli which contributes to the mechanical shape and structure of Шаблон:Gli, Шаблон:Gli, or Шаблон:Gli (e.g. collagen and actin), as distinguished from proteins which serve some other purpose, such as Шаблон:Gli. This distinction is not well-defined, however, as many proteins have both structural and non-structural roles.[2]
1. The subdivision of the interior of a cell into functionally distinct spaces or Шаблон:Gli (e.g. Шаблон:Gli) and the delegation of particular cellular functions and activities to these particular spaces.
2. The determination by any of various laboratory methods (e.g. fluorescent Шаблон:Gli) of the precise location(s) within a cell where a specific molecule has occupancy, or at which a specific activity occurs.
(of a linear Шаблон:Gli or chromosome fragment) Having a Шаблон:Gli positioned close to but not exactly in the middle of the chromosome, resulting in Шаблон:Gli arms of slightly different lengths.[6] Compare Шаблон:Gli.
1. A chemical compound or molecule upon which a particular Шаблон:Gli directly acts, often but not necessarily binding the molecule by forming one or more chemical bonds.[2] See also Шаблон:Gli.
2. The substance, biotic or abiotic, upon which an organism grows or lives, or by which it is supported; e.g. a particular Шаблон:Gli used in Шаблон:Gli. See also Шаблон:Gli.
A single unit of a multi-unit compound or molecular aggregate; e.g. a Шаблон:Gli from which a larger Шаблон:Gli is composed (as with Шаблон:Gli in Шаблон:Gli), or an individual Шаблон:Gli chain in a multi-chain Шаблон:Gli, or an entire protein which participates alongside other proteins as part of a Шаблон:Gli.[2][4]
A type of Шаблон:Gli in which a Шаблон:Gli is conjugated to a polar residue of another protein (usually a lysine) via a covalent Шаблон:Gli. This effectively Шаблон:Gli the second protein, making it distinguishable to other biomolecules and in many cases allowing it to participate in specific reactions or to interact with specific Шаблон:Gli. SUMOlyation is closely related to Шаблон:Gli, relying on the same E1/E2/E3 enzymes to transfer SUMO to specific recognition motifs in the target protein, though detaching SUMO depends on SUMO-specific Шаблон:Gli. It plays important roles in numerous cellular processes, including Шаблон:Gli, transcriptional regulation, stress-response pathways, and Шаблон:Gli, among others. SUMOlyation is also used in the laboratory as a molecular Шаблон:Gli and to help solubilize proteins which are difficult to Шаблон:Gli.
A type of Шаблон:Gli in which individual Шаблон:Gli or aggregates of cells are suspended in a liquid Шаблон:Gli, and usually prevented from settling by continuous gentle agitation. Many prokaryotic and eukaryotic cell types readily proliferate in suspension cultures, but they are particularly useful for culturing non-adherent cell lines such as hematopoietic cells, plant cells, and insect cells. Compare Шаблон:Gli.
Any of a class of Шаблон:GliШаблон:Gli which facilitate the transport of two or more different molecules across the membrane at the same time and in the same direction; e.g. glucose and sodium ions. Contrast Шаблон:Gli and Шаблон:Gli.
A Шаблон:Gli cell, i.e. a cell containing more than one Шаблон:Gli or, in the broadest sense, more than one Шаблон:Gli (a meaning which is equated with Шаблон:Gli). Syncytia may form as a result of Шаблон:Gli between uninucleate cells, migration of a nucleus from one cell to another, or multiple nuclear divisions without accompanying Шаблон:Gli (forming a Шаблон:Gli).[9] The term may also refer to cells which are interconnected by specialized membranes with Шаблон:Gli as in some neuromuscular cell types.
The aggregation of Шаблон:Gli into a dense knot that adheres to one side of the Шаблон:Gli, commonly observed during Шаблон:Gli in certain organisms.[13]
A type of Шаблон:Gli in which the Шаблон:Gli of one Шаблон:Gli base for another results, after Шаблон:Gli and Шаблон:Gli, in an amino acid sequence which is identical to the original unmutated sequence. This is possible because of the Шаблон:Gli of the Шаблон:Gli, which allows different Шаблон:Gli to code for the same amino acid. Though synonymous mutations are often considered Шаблон:Gli, this is not always the case; a synonymous mutation may affect the efficiency or accuracy of Шаблон:Gli, Шаблон:Gli, Шаблон:Gli, or any other process by which genes are Шаблон:Gli, and thus become effectively non-silent. Contrast Шаблон:Gli.
A pattern within a Шаблон:Gli in which one or more Шаблон:Gli are repeated and the repetitions are directly adjacent (i.e. tandem) to each other. An example is Шаблон:Font, in which the sequence Шаблон:Font is repeated three times.
The site or locus upon another molecule at which a protein performs a particular biochemical activity; e.g. the nucleotide Шаблон:Gli at which a Шаблон:Gli cleaves a DNA molecule, often but not necessarily the same as the enzyme's Шаблон:Gli (i.e. a restriction enzyme may recognize one motif, known as a Шаблон:Gli, and cleave at another).[5]
A directional response by a cell or a population of cells to a specific stimulus; a movement or other activity occurring in a non-random direction and dependent on the direction from which the stimulus originated.[3] This contrasts with Шаблон:Gli, a response without directional bias.
The transmission of three‐dimensional structural stability from a stable part of a macromolecule to a distal part of the same molecule, especially an inherently less stable part.[5] Instability may also be transmitted in this way, e.g. destabilization of the DNA Шаблон:Gli may occur at a Шаблон:Gli that is relatively distant from the Шаблон:Gli of a Шаблон:Gli.[13]
(of a linear Шаблон:Gli or chromosome fragment) Having a Шаблон:Gli positioned at the terminal end of the chromosome (near or within the Шаблон:Gli), resulting in only a single arm.[6] Compare Шаблон:Gli.
A region of Шаблон:GliШаблон:Gli at each end of a linear Шаблон:Gli which protects the end of the chromosome from deterioration and from fusion with other chromosomes. Since each round of Шаблон:Gli results in the shortening of the chromosome, telomeres act as disposable buffers which are sacrificed to perpetual truncation instead of nearby genes; telomeres can also be lengthened by the enzyme telomerase.
A DNA Шаблон:Gli or its RNA Шаблон:Gli which signals the termination of Шаблон:Gli by triggering processes that ultimately arrest the activity of Шаблон:Gli or otherwise cause the release of the RNA Шаблон:Gli from the transcriptional complex. Terminator sequences are usually found near the Шаблон:Gli of the Шаблон:Gli of Шаблон:Gli or Шаблон:Gli. They generally function after being themselves transcribed into the nascent RNA strand, whereupon the part of the strand containing the sequence either directly interacts with the transcriptional complex or forms a Шаблон:Gli such as a Шаблон:Gli which signals the recruitment of enzymes that promote its disassembly.[13]
One of the four standard Шаблон:Gli used in Шаблон:Gli molecules, consisting of a Шаблон:GliШаблон:Gli with its N9 nitrogen Шаблон:Gli to the C1 carbon of a Шаблон:Gli sugar. The prefix deoxy- is commonly omitted, since there are no ribonucleoside analogs of thymidine used in RNA, where it is replaced with Шаблон:Gli instead.
A type of specialized intercellular junction characterized by very close contact between the plasma membranes of adjacent cells, which are held together by large Шаблон:Gli that completely or nearly completely occlude the passage of water and solutes through the Шаблон:Gli between cells. Tight junctions occur in many vertebrate tissues, especially between the epithelial and endothelial cells that line the surfaces of most organs and vessels. These cells are completely encircled by tight junctions which create a gasket-like seal that separates each cell's plasma membrane into apical and basolateral domains and prevents the exchange of extracellular materials between them.[5][3]
In a multicellular organism, a contiguous aggregation of Шаблон:Gli held together by a common Шаблон:Gli and specialized to perform a particular function. Some tissues are composed primarily of a single cell type; others are a heterogeneous mixture of many cell types.[2] Tissues represent a level of multicellular organization between that of individual cells and that of organs, which may be composed of one or more distinct types of tissue.[3]
The growth and maintenance, or "culturing", of multicellular Шаблон:Gli, or of cells harvested from tissues, under carefully controlled conditions Шаблон:Gli, in the strictest sense by taking a piece of explanted tissue directly from a living plant or animal and maintaining it outside of the body of the source organism. In common usage, the term may also refer to Шаблон:Gli in general, especially when growing certain cell types which have been harvested from tissues but dispersed from their original tissue-specific organization into a population of more or less independently growing cells.[3]
Gene function and Шаблон:Gli which is restricted to a particular Шаблон:Gli or cell type. Tissue-specific expression is usually the result of an Шаблон:Gli which is activated only in the proper cell type.
A measure of the effective osmotic pressure gradient of one solution relative to another solution, used especially to describe the water potential that exists between two aqueous solutions separated by a semipermeable membrane (as with a Шаблон:Gli, where the intracellular Шаблон:Gli is separated from the Шаблон:Gli by the Шаблон:Gli). Tonicity depends on the relative concentrations of solutes on either side of the membrane, which determine the direction and extent to which solvent molecules move across the membrane by Шаблон:Gli; it is affected only by those solutes which cannot cross the membrane, as those which can cross freely can achieve equilibrium without any net movement of solute. The extracellular environment is commonly described as Шаблон:Gli, Шаблон:Gli, or Шаблон:Gli with respect to the intracellular environment.
Шаблон:Gli describes the pressure to restore Шаблон:Gli between the inside and outside of cells by moving water across the cell membrane. Red blood cells tend to lose water and shrivel up in a severely Шаблон:Gli environment (left) or gain water and swell to bursting in a severely Шаблон:Gli environment (right), but the water potential is balanced in an Шаблон:Gli environment (center).
Any of a class of Шаблон:Gli enzymes which catalyze changes in the topological state of a Шаблон:Gli molecule by Шаблон:Gli or Шаблон:Gli the Шаблон:Gli of one or both strands, relaxing the torsional stress inherent in the Шаблон:Gli and unwinding or untangling the paired strands before Шаблон:Gli the nicks. This process is usually necessary prior to Шаблон:Gli and Шаблон:Gli. Topoisomerases thereby convert DNA between its Шаблон:Gli and Шаблон:Gli, linked and unlinked, and knotted and unknotted forms without changing the sequence or overall chemical composition, such that the substrate and product molecules are structural isomers, differing only in their shape and their Шаблон:Gli, Шаблон:Gli, and/or Шаблон:Gli.
A state of Шаблон:Gli in which a cell or nucleus fully retains the ability to Шаблон:Gli into all of the Шаблон:Gli represented in the adult organism, or to give rise to all of these cell types upon Шаблон:Gli into an appropriate cytoplasm (as in Шаблон:Gli). Such cells or nuclei are said to be totipotent. The Шаблон:Gli that serves as the progenitor cell for sexually reproducing multicellular organisms is the archetypal totipotent cell; almost all of the cells into which it ultimately differentiates are not totipotent, though some cells such as Шаблон:Gli remain totipotent or Шаблон:Gli throughout the organism's life.[2]
A molecule or a specific atom within a molecule that has been chemically or radioactively Шаблон:Gli so that it can be easily tracked or followed through a biochemical process or located in a cell or tissue.[4]
Affecting a Шаблон:Gli or sequence on a different nucleic acid molecule or Шаблон:Gli. A Шаблон:Gli or sequence within a particular DNA molecule such as a Шаблон:Gli is said to be trans-acting if it or its Шаблон:Gli influence or act upon other sequences located relatively far away or on an entirely different molecule or chromosome. For example, a Шаблон:Gli acts "in trans" if it binds to or interacts with a sequence located on any strand or molecule different from the one on which it is encoded. Contrast Шаблон:Gli.
A form of Шаблон:Gli in which different RNA Шаблон:Gli, synthesized in separate Шаблон:Gli events, are spliced together into a single, continuous transcript. This contrasts with the more conventional "cis-splicing", where segments of the same transcript are excised or re-arranged.[3]
An experimental approach to artificially control Шаблон:Gli by introducing a transactivator gene under the control of an inducible Шаблон:Gli into a genome. The transactivator encodes a Шаблон:Gli capable of Шаблон:Gli upon one or more other genes by recognizing and specifically binding their promoters; thus by inducing the transactivator gene, the expression of many other genes can be experimentally manipulated.[3]
A product of Шаблон:Gli; that is, any Шаблон:Gli molecule which has been synthesized by Шаблон:Gli using a complementary Шаблон:Gli molecule as a Шаблон:Gli. When transcription is completed, transcripts separate from the DNA and become independent Шаблон:Gli. Particularly in eukaryotes, multiple Шаблон:Gli are usually necessary for raw transcripts to be converted into stable and persistent molecules, which are then described as mature, though not all transcribed RNAs undergo maturation. Many transcripts are accidental, spurious, incomplete, or defective; others are able to perform their functions immediately and without modification, such as certain Шаблон:Gli.
Any RNA Шаблон:Gli whose function is unclear. Such transcripts may include functional Шаблон:Gli which have not yet been studied in detail as well as spurious transcripts without any definite function. The DNA sequences from which TUFs are transcribed are generally located in Шаблон:Gli or Шаблон:Gli regions of the genome. See also Шаблон:Gli.
The first step in the process of Шаблон:Gli, in which an Шаблон:Gli molecule, known as a Шаблон:Gli, is synthesized by enzymes called Шаблон:Gli using a Шаблон:Gli or other Шаблон:Gli sequence as a Шаблон:Gli. Transcription is a critical and fundamental process in all living organisms and is necessary in order to make use of the information encoded within a Шаблон:Gli. All classes of RNA must be transcribed before they can exert their effects upon a cell, though only Шаблон:Gli (mRNA) proceeds to Шаблон:Gli to produce a functional Шаблон:Gli, whereas the many types of Шаблон:Gli fulfill their duties without being translated. Transcription is also not always beneficial for a cell: when it occurs at the wrong time or at a Шаблон:Gli, or when Шаблон:Gli or infectious pathogens utilize the host's transcription machinery, the resulting transcripts (not to mention the waste of valuable energy and resources) are often harmful to the host cell or genome.
A simplified diagram of Шаблон:Gli. RNA polymerase (RNAP) synthesizes an RNA transcript (blue) in the 5'-to-3' direction, using one of the DNA strands as a Шаблон:Gli, while a complex of multiple Шаблон:Gli binds to a Шаблон:Gli upstream of the gene.
Any Шаблон:Gli that controls the rate of Шаблон:Gli of genetic information from Шаблон:Gli to Шаблон:Gli by binding to a specific Шаблон:Gli and Шаблон:Gli or Шаблон:Gli the recruitment of Шаблон:Gli to nearby Шаблон:Gli. Transcription factors can effectively turn "on" and "off" specific genes in order to make sure they are Шаблон:Gli at the right times and in the right places; for this reason, they are a fundamental and ubiquitous mechanism of Шаблон:Gli.
The specific location within a Шаблон:Gli at which Шаблон:Gli begins Шаблон:Gli, defined by the specific nucleotide or codon corresponding to the first ribonucleotide(s) to be assembled in the Шаблон:Gli transcript (which is not necessarily the same as the Шаблон:Gli to be Шаблон:Gli). This site is usually considered the beginning of the Шаблон:Gli and is the reference point for numbering the individual nucleotides within a gene. Nucleotides Шаблон:Gli of the start site are assigned negative numbers and those Шаблон:Gli are assigned positive numbers, which are used to indicate the positions of nearby sequences or structures relative to the TSS. For example, the Шаблон:Gli for RNA polymerase might be a short sequence immediately upstream of the TSS, from approximately -80 to -5, whereas an Шаблон:Gli within the coding region might be defined as the sequence starting at nucleotide +207 and ending at nucleotide +793.
The segment of DNA between the Шаблон:Gli and the termination site of Шаблон:Gli, containing the Шаблон:Gli for one or more Шаблон:Gli. All genes within a transcription unit are transcribed together into a single transcript during a single transcription event; the resulting Шаблон:Gli RNA may subsequently be cleaved into separate RNAs, or may be Шаблон:Gli as a unit and then cleaved into separate polypeptides.[13]
The intermittent nature of Шаблон:Gli and Шаблон:Gli mechanisms. Both processes occur in "bursts" or "pulses", with periods of gene activity separated by irregular intervals.
The entire set of Шаблон:Gli molecules (often referring to all types of RNA but sometimes exclusively to Шаблон:Gli) that is or can be Шаблон:Gli by a particular Шаблон:Gli, cell, population of cells, or species at a particular time or under particular conditions. The transcriptome is distinct from the Шаблон:Gli and the Шаблон:Gli.
The study of the Шаблон:Gli of a particular genome, cell, or organism, i.e. the sum total of all of the RNA Шаблон:Gli produced from it by Шаблон:Gli. Transcriptomics technologies allow scientists to isolate and sequence transcriptomes, which can then be mapped to the genome to determine which genes are being expressed or which cellular processes are active and which are dormant at a given time.
The transport of molecules across the interior of a cell, i.e. through the Шаблон:Gli, especially a Шаблон:Gli such as an Шаблон:Gli with contrasting Шаблон:Gli and Шаблон:Gli surfaces, thereby providing a spatially oriented transport system. Molecules undergoing transcytosis are usually contained within Шаблон:Gli.[5]
The deliberate experimental introduction of exogenous Шаблон:Gli into a cell or embryo. In the broadest sense the term may refer to any such transfer and is sometimes used interchangeably with Шаблон:Gli, though some applications restrict the usage of transfection to the introduction of naked or purified non-viral Шаблон:Gli or Шаблон:Gli into cultured eukaryotic cells (especially animal cells) resulting in the subsequent incorporation of the foreign DNA into the host Шаблон:Gli or the non-hereditary modification of Шаблон:Gli by the foreign RNA. As a contrast to both standard non-viral transformation and Шаблон:Gli, transfection has also occasionally been used to refer to the uptake of purified viral nucleic acids by bacteria or plant cells without the aid of a viral vector.[13]
A special class of Шаблон:Gli molecule, typically 76 to 90 Шаблон:Gli in length, that serves as a physical adapter allowing Шаблон:Gli transcripts to be Шаблон:Gli into sequences of Шаблон:Gli during protein synthesis. Each tRNA contains a specific Шаблон:Gli triplet corresponding to an amino acid that is covalently attached to the tRNA's opposite end; as translation proceeds, tRNAs are recruited to the Шаблон:Gli, where each mRNA Шаблон:Gli is paired with a tRNA containing the complementary anticodon. Depending on the organism, cells may employ as many as 41 distinct tRNAs with unique anticodons; because of Шаблон:Gli within the Шаблон:Gli, several tRNAs containing different anticodons carry the same amino acid.
A type of RNA molecule in some bacteria which has dual Шаблон:Gli-like and Шаблон:Gli-like properties, allowing it to simultaneously perform a number of different functions during Шаблон:Gli.
Any Шаблон:Gli or other segment of genetic material that has been isolated from one organism and then transferred either naturally or by any of a variety of Шаблон:Gli techniques into another organism, especially one of a different species. Transgenes are usually introduced into the second organism's Шаблон:Gli. They are commonly used to study gene function or to confer an advantage not otherwise available in the unaltered organism.
The entire set of Шаблон:Gli molecules that are Шаблон:Gli by a particular Шаблон:Gli, cell, tissue, or species at a particular time or under particular conditions. Like the Шаблон:Gli, it is often used as a proxy for quantifying levels of Шаблон:Gli, though the transcriptome also includes many RNA molecules that are never translated.
Any of a diverse variety of Шаблон:GliШаблон:Gli consisting of self-acting DNA sequences capable of Шаблон:Gli themselves semi-autonomously and Шаблон:Gli into random or specific sites within a host genome, a process known as Шаблон:Gli. Transposons contain one or more genes which encode enzymes known as Шаблон:Gli capable of recognizing sequences within a flanking pair of Шаблон:Gli, such that the enzymes effectively catalyze their own replication, Шаблон:Gli, and/or re-insertion into other DNA molecules by any of various mechanisms.[3]
Any of a class of self-acting Шаблон:Gli capable of Шаблон:Gli to the flanking sequences of the Шаблон:Gli which encodes them and catalyzing its movement to another part of the genome, typically by an Шаблон:Gli/Шаблон:Gli mechanism or a replicative mechanism, in a process known as Шаблон:Gli.
The process by which a nucleic acid sequence known as a Шаблон:Gli changes its position within a Шаблон:Gli, either by Шаблон:Gli and re-inserting itself at a different Шаблон:Gli (cut-and-paste) or by Шаблон:Gli itself and inserting into another locus without moving the original element from its original locus (copy-paste). These reactions are catalyzed by an enzyme known as a Шаблон:Gli which is encoded by a gene within the transposable element itself; thus the element's products are self-acting and can autonomously direct their own replication. Transposed sequences may re-insert at random loci or at sequence-specific targets, either on the same DNA molecule or on different molecules.
Any of a class of chemical compounds which are ester derivatives of glycerol, consisting of a glycerol backbone connected to any three Шаблон:Gli substituents via ester bonds. Triglycerides are one of three major classes of esters formed by fatty acids in biological systems, along with Шаблон:Gli and cholesteryl esters. They are the primary constituent of Шаблон:Gli tissue in vertebrates.
Any sequence in which an individual nucleotide Шаблон:Gli is Шаблон:Gli many times Шаблон:Gli, whether in a gene or non-coding sequence. At most Шаблон:Gli some degree of repetition is normal and harmless, but mutations which cause specific triplets (especially those of the form Шаблон:Font) to increase in Шаблон:Gli above the normal range are highly unstable and responsible for a variety of Шаблон:Gli.
A unit of three successive Шаблон:Gli in a Шаблон:Gli or Шаблон:Gli molecule.[13] A triplet within a coding sequence that codes for a specific amino acid is known as a Шаблон:Gli.
The directional growth or movement of a cell or organism in response to a stimulus, e.g. light, heat, the pull of gravity, or the presence of a particular chemical, such that the response is dependent on the direction of the stimulus (as opposed to a non-directional Шаблон:Gli). Positive tropism is growth or movement toward the stimulus; negative tropism is away from the stimulus.[2] See also Шаблон:Gli and Шаблон:Gli.
The force within a cell which pushes the Шаблон:Gli against the Шаблон:Gli,[32] a type of hydrostatic pressure influenced by the Шаблон:Gli of water into and out of the cell. Turgidity is observed in plants, fungi, bacteria, and some protists with cell walls, but generally not in animal cells.
In Шаблон:Gli, a measure of the rate at which a particular Шаблон:GliШаблон:Gli a particular biochemical reaction, usually expressed as the average number of Шаблон:Gli molecules it is capable of converting into reaction products per unit time at a given concentration of enzyme.[33]
The Шаблон:Gli of a biomolecule (often another protein) by covalently attaching a Шаблон:Gli protein to it—generally via the formation of an amide bond between the ubiquitin's C-terminal glycine and positively charged side chains (often lysine or arginine residues) of the labelled molecule, an Шаблон:Gli-dependent reaction catalyzed by ubiquitin-conjugating enzymes[3]—thus making it identifiable to molecules capable of recognizing ubiquitin Шаблон:Gli. Ubiquitination is a widely used Шаблон:Gli by which proteins are Шаблон:Gli; the attachment of a single ubiquitin molecule (monoubiquitination) can variously activate or inhibit a protein's activity, while the attachment of a chain of multiple consecutively linked ubiquitin molecules (polyubiquitination) commonly targets the protein for degradation by Шаблон:Gli.
A type of Шаблон:Gli which catalyzes the movement of a single, specific solute or chemical species across a lipid membrane in either direction.[4] Contrast Шаблон:Gli and Шаблон:Gli.
A class of DNA Шаблон:Gli determined by Шаблон:Gli to be present only once in the analyzed genome, as opposed to Шаблон:Gli. Most structural genes and their introns are unique.[13]
Any Шаблон:Gli sequence which is transcribed along with a Шаблон:Gli, and thus included within a Шаблон:Gli, but which is not ultimately Шаблон:Gli during protein synthesis. A typical mRNA transcript includes two such regions: one immediately upstream of the coding sequence, known as the Шаблон:Gli (5'-UTR), and one downstream of the coding sequence, known as the Шаблон:Gli (3'-UTR). These regions are not removed during Шаблон:Gli (unlike Шаблон:Gli) and are usually considered distinct from the Шаблон:Gli and the Шаблон:Gli (both of which are later additions to a primary transcript and not themselves products of transcription). UTRs are a consequence of the fact that transcription usually begins considerably upstream of the Шаблон:Gli of the coding sequence and terminates long after the Шаблон:Gli has been transcribed, whereas translation is more precise. They often include motifs with regulatory functions.
Any process, natural or artificial, which increases the level of Шаблон:Gli of a certain Шаблон:Gli. A gene which is observed to be expressed at relatively high levels (such as by detecting higher levels of its Шаблон:Gli transcripts) in one sample compared to another sample is said to be upregulated. Contrast Шаблон:Gli.
A type of Шаблон:Gli found in the DNA of yeast such as Saccharomyces cerevisiae, usually a few hundred base pairs upstream of the Шаблон:Gli within the Шаблон:Gli of a protein-coding gene, which helps to increase the gene's expression by serving as a binding site for transcriptional Шаблон:Gli, analogous to the function of an Шаблон:Gli in multicellular eukaryotes.[34][5]
Any of a class of Шаблон:Gli, fluid-filled Шаблон:Gli present in many eukaryotic cells as well as bacteria, often large and conspicuous under the microscope and serving any of a huge variety of functions, including acting as a resizable reservoir for the storage of water, Шаблон:Gli, toxins, or foreign material; maintaining cellular Шаблон:Gli and Шаблон:Gli; supporting immune functions; housing symbiotic bacteria; and assisting in the Шаблон:Gli of old cellular components.[2]
Any of a class of Шаблон:Gli for which the Шаблон:Gli of the Шаблон:Gli at a particular locus tends to vary between individuals of the same species. VNTRs may occur throughout the genome, both within and outside of Шаблон:Gli, and if the copy number is stably inherited may be used in Шаблон:Gli to uniquely identify individuals or to determine their genealogical relatedness to other individuals.
Variation or irregularity in a particular Шаблон:Gli, especially a conspicuous visible Шаблон:Gli such as color or pigmentation, occurring simultaneously in different parts of the same individual organism due to any of a variety of causes, such as Шаблон:Gli, Шаблон:Gli, Шаблон:Gli activity, Шаблон:Gli, or infection by pathogens.
Any Шаблон:Gli molecule used as a vehicle to artificially transport foreign genetic material into another cell, where it can be Шаблон:Gli and/or Шаблон:Gli. Vectors are typically engineered Шаблон:Gli sequences consisting of an Шаблон:Gli (often a Шаблон:Gli) and a longer "backbone" sequence containing an Шаблон:Gli, a Шаблон:Gli, and a Шаблон:Gli. Vectors are widely used in molecular biology laboratories to isolate, Шаблон:Gli, or Шаблон:Gli the insert in the target cell.
Any Шаблон:Gli space completely enclosed by its own Шаблон:Gli, which is separate though usually derived from other membranes (often the Шаблон:Gli) either by Шаблон:Gli or by mechanical disruption such as Шаблон:Gli.[3] The term is applied to many different structures but especially to the small, roughly spherical Шаблон:Gli created during Шаблон:Gli and Шаблон:Gli, as well as to Шаблон:Gli and various other small intracellular or extracellular organelles.[2]
The process of Шаблон:Gli the entirety or near-entirety of the DNA sequences comprising an organism's Шаблон:Gli with a single procedure or experiment, generally inclusive of all Шаблон:Gli and Шаблон:Gli (e.g. Шаблон:Gli) DNA.
The Шаблон:Gli of the typical form of a species as it occurs in nature; a product of the standard "normal" Шаблон:Gli at a given Шаблон:Gli, as opposed to that produced by a non-standard Шаблон:Gli allele.
An index of the Шаблон:Gli of a DNA molecule. The writhing number does not have a precise quantitative definition but instead represents the degree of supercoiling. Together, the writhing number and the Шаблон:Gli determine the Шаблон:Gli.[5]
One of two Шаблон:Gli present in organisms which use the XY sex-determination system, and the only sex chromosome in the X0 system. The X chromosome is found in both males and females and typically contains much more Шаблон:Gli content than its counterpart, the Шаблон:Gli.
The process by which one of the two copies of the Шаблон:Gli is silenced by being irreversibly condensed into transcriptionally inactive Шаблон:Gli in the cells of female therian mammals. A form of Шаблон:Gli, X-inactivation prevents females from producing twice as many Шаблон:Gli from genes on the X chromosome as males, who only have one copy of the X chromosome. Which X chromosome is inactivated is randomly determined in the early embryo, making it possible for cell lineages with different inactive Xs to exist in the same organism.
One of two Шаблон:Gli present in organisms which use the XY sex-determination system. The Y chromosome is found only in males and is typically much smaller than its counterpart, the Шаблон:Gli.
A Шаблон:GliШаблон:Gli structural motif and Шаблон:Gli occurring in many Шаблон:Gli, characterized by a series of non-adjacent amino acid Шаблон:Gli which Шаблон:Gli into a three-dimensional arrangement capable of coordinating one or more zinc ions (Шаблон:Chem) between them, thus stabilizing the fold into a definite structure that can interact specifically with other biomolecules such as nucleic acids or other polypeptides. There are many distinct classes of zinc fingers using different ligands and spatial arrangements to achieve coordination; in perhaps the most common variant, a short Шаблон:Gli is oriented antiparallel to a Шаблон:Gli, with two histidine residues in the former and two cysteines in the latter forming the coordination complex. Zinc fingers bind DNA as the primary functional domain of many Шаблон:Gli.
The degree to which multiple copies of a Шаблон:Gli, Шаблон:Gli, or Шаблон:Gli have the same genetic sequence; e.g. in a diploid organism with two complete copies of its genome (one maternal and one paternal), the degree of similarity of the Шаблон:Gli present in each copy. Individuals carrying two different alleles for a particular gene are said to be Шаблон:Gli for that gene; individuals carrying two identical alleles are said to be Шаблон:Gli for that gene. Zygosity may also be considered collectively for a group of genes, or for the entire set of genes and genetic Шаблон:Gli comprising the genome.
A type of eukaryotic cell formed as the direct result of a fertilization event between two Шаблон:Gli. In multicellular organisms, the zygote is the earliest developmental stage.
↑overexpression. Oxford University Press (2017). — «The production of abnormally large amounts of a substance which is coded for by a particular gene or group of genes; the appearance in the phenotype to an abnormally high degree of a character or effect attributed to a particular gene.»
↑overexpress. National Cancer Institute at the National Institutes of Health (2011-02-02). — «overexpress In biology, to make too many copies of a protein or other substance. Overexpression of certain proteins or other substances may play a role in cancer development.»
