|
Home >> Dictionary of Bioinformatics, Biochemistry, Biotechnology >> Gamma Chain - Gas Solid Chromatography
|
|
GALT
An acronym for Gut Associated Lymphatic Tissue. Patches of lymphoid tissue in the same intestine; Payer’s patches.
Gamete
A mature reproductive cell containing haploid chromosomes that is capable of fusing with a cell of opposite sex to form a zygote from which a new organism can develop. In plants, refers to pollen, spermatic nucleolus, or ovum. In animals, a gamete is a sperm or egg.
Gametoclone
A plant that is regenerated from a tissue culture derived from gametic tissue.
|
Gamma delta T cells
T cells with T cell receptor composed of gamma and delta chains instead of the alpha and beta chains.
Gamma(γ)-glutamyl cycle
A mechanism for amino acid transport, which involves glutathione and glutathione-dependent enzymes. Glutathione reacts with an amino acid to form γ-glutamyl amino acid, which is transported across the cell membrane to the cytoplasm where the amino acid is released. The γ-glutamyl moiety is used to resynthesise glutathione.
|
Gamma-glutamyl transpeptidase (GGT)
An enzyme that catalyses the transfer of a gamma-glutamyl group from peptides to acceptors. GGT is present in the Microsomes and cell membrane of cells with high secretory and/or excretory functions. The enzyme is found in the kidney, liver, pancreas and prostate. Although highest activity is seen in kidneys, the hepatobiliary system is the source of the plasma enzyme.
Plasma GGT activity is elevated in all types of liver disease and extremely high GGT is indicative of chronic cholestasis and/or liver malignancy. Enzyme activity is also increased by ingestion of alcohol and drugs such as Phenobarbitone, phenytoin, antidepressants, antituberculosis drugs such as rifampicin, and contraceptives, which cause enzyme induction. High values of GGT are seen in primary and secondary neoplasm.
|
|
Ganglion (pl. ganglia)
A cluster or nerve cells and associated glial cells found outside the central nervous system.
Ganglioside
Sphingolipid containing complex oligosaccharides as head groups.
Gangrene
Tissue death followed by bacterial infection and putrefaction.
|
|
|
Gap
1. The phase of the cell cycle between M and S phase. There are two gap phases G1 (before S phase) and G2 (after S phase). 2. Admission sequence in one of the strands of dsDNA. The DNA will have a single-stranded region. 3. In bioinformatics, refers to a part of a sequence alignment in which one sequence contains no aligned monomer. This can be interpreted in terms of evolutionary insertion and deletion of monomers.
Gamma interferon
See interferon.
|
Gamma radiation
A high-energy electromagnetic radiation produced during the process of nuclear decay in which one subatomic particle is converted to another such as decay of a neutron into a proton and electron.
Gametogenesis
The process of formation of gametes.
Gamma-aminobutyric acid
See GABA.
Gamma chain
An immunoglobulin (lgG) chain founds as a transmembrane protein on the surface of B cell-antigen receptor complex.
GAP
GTPase activating proteins. A class of proteins that inactivates ras-GTP by hydrolysis of bound GTP to form ras-GDP. The ras-GDP complex is inactive until the GDP is exchanged for GTP. Inactivation of ras-GTP by GAPs plays an important role in ras-mediated signal transduction.
Gap genes
A group of genes including hunchback and knirps found in Drosophila that are activated in the early embryo by transcription factors produced from maternal mRNA in the zygote. The gap genes encode transcription factors that play a role in early pattering along the anterioposterior axis.
Gap junction
A cell-cell junction that permits ions and small molecules to pass from the cytoplasm of one cell to the cytoplasm of an adjacent cell.
GAP mutants
Mutants of the fruit fly Drosophila melanogaster in which several adjacent segments fail to appear during development.
Gap penalties
The penalty applied to a similarity score for the introduction of an insertion or deletion gap or the extension of a gap. Gap penalties are subtracted from a cumulative score when comparing two or more sequences via an optimisation algorithm that attempts to maximize that score.
Gapped DNA
A double-stranded DNA with one or more internal single-stranded regions.
Gaps (affine gaps)
Any maximal consecutive run of spaces in a single string of a given alignment. Gaps help create alignments that conform to underlying biological models and to take into account the number of continuous gaps and not only the number of spaces when calculating an alignment. Affine gaps contain a component for gap insertion and a component for gap extension. The penalty for extension is generally lower than that for insertion that mimics biological reality as multiple gaps imply multiple mutations, whereas a single mutation can lead to a long gap.
Gas chromatography
A chromatographic technique in which the mobile phase is a gas and the stationary phase is a liquid or a solid. Based on the nature of the station phase, gas chromatography is divided into two types-gas liquid and gas solid chromatography.
Gas gangrene
A highly fatal disease caused by the contamination of wounds by different species of Clostridium. The clostridia release exotoxins and ferment muscle sugars to release gas that causes tissue damage.
Gas-liquid chromatography (GLC)
A technique based on distribution of compounds between a liquid and a gas phase. The mobile phase is a gas and the stationary phase is a liquid adsorbed either to the inner surface of a column or to supports such as diatomaceous earth, Teflon powder or fine glass beads. The stationary phase is a liquid usually applied as a solid dissolved in a volatile solvent such as ether. For example, beads are dipped into a solution of polyethylene glycol (PEG) in ether. When the ether evaporates, each bead in coated with PEG. At the temperature used for GLC, PEG melts and remains on the bead as a liquid film. GLC is used in the separation of alcohols, esters, fatty acids, and amines.
Gas solid chromatography
A type of adsorption chromatography in which a gas functions as the mobile phase and a solid adsorbent such as silica or alumina as the stationary phase. It is not widely used due to poor reproducibility.
Gas transfer
The rate at which gases are transferred from gas into solution. This is an important parameter in fermentation because it controls the metabolic rate of the organism. Gas transfer can be achieved by use of small gas bubbles that diffuse faster than large bubbles because of their larger surface area per unit of volume. Gas transfer can also be done by spreading the liquid out on a thin sheet, or in a thin permeable tube, as in hollow fibre bioreactor.
Gasohol
A mixture of 90 per cent gasoline and 10 per cent ethanol that is a more energy efficient alternative to gasoline.
Gastrectomy
Surgical removed of the stomach.
Gastric mucus
A secretion by gastric mucosal epithelium and gastric glands. It functions as a lubricant protecting the mucosa from injury.
Gastrin
A hormone secreted by the gastric antrum and duodenum that stimulates gastric acid and pepsin. Gastrin present in the gastric antral mucosa is a heptadecapeptide containing 17 amino acid residues (G-17). The principal form of serum gastrin is G-34, containing 34 amino acids. Gastrin stimulates gastric acid secretion by interacting with receptors on the parietal cell. Although the exact mechanism of action is unknown, it may mediate its effects by causing changes in Ca2+ flux. Synthesis of gastrin is stimulated by peptides and amino acids as well as by the vagus nerve. Gastrin production is inhibited by low pH and by the hormones secretin and somatostatin.
|
|
