| catabolite repression | <biochemistry, molecular biology> Inducible enzyme systems in some microorganisms (such as the lac operon) that are repressed when a more favoured carbon source, such as glucose, is available. Repression in E. Coli is partially relieved if cAMP is bound to the cAMP catabolite activator protein (cAMP receptor protein, CRP) that binds to DNA upstream of the repressed operon concerned. Catabolite repression (of the respiratory system) is seen in yeast in high glucose concentrations, though the mechanism is different. (16 Mar 1998) |
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| repression | The inhibition of a gene's expression, this is typically caused by the change in the activity of a regulatory protein. (09 Oct 1997) |
| repression-sensitization | Defense mechanisms involving approach and avoidance responses to threatening stimuli. The sensitizing process involves intellectualization in approaching or controlling the stimulus whereas repression involves unconscious denial in avoiding the stimulus. (12 Dec 1998) |
| primal repression | Repression of material never in conscious thought. (05 Mar 2000) |
| end product repression | Catabolite repression in which the catabolite is an end product of a particular pathway. (05 Mar 2000) |
| enzyme repression | The interference in synthesis of an enzyme due to the elevated level of an effector substance, usually a metabolite, whose presence would cause depression of the gene responsible for enzyme synthesis. (12 Dec 1998) |
| allelic gene | See: allele, dominance of traits. (05 Mar 2000) |
| antibiotic resistance gene | Genes in a microorganism which confer resistance to antibiotics, for example by coding for enzymes which destroy it, by coding for surface proteins which prevent it from entering the microorganism, or by being a mutant form of the antibiotic's target so that it can ignore it. (09 Oct 1997) |
| autosomal gene | A gene located on any chromosome other than the sex chromosomes (X or Y). (05 Mar 2000) |
| bicoid gene | A group of genes which are important to the proper development of the head and thorax in the embryo of the fruit fly Drosophila melanogaster. (09 Oct 1997) |
| BRCA1 breast cancer susceptibility gene | This mutated (changed) version of the BRCA1 gene makes a person susceptible to developing breast cancer. (12 Dec 1998) |
| calcitonin gene-related peptide | <protein> A second product transcribed from the calcitonin gene. Calcitonin gene related peptide is found in a number of tissues including nervous tissue. It is a vasodilator that may participate in the cutaneous triple response. It is a neuropeptide of 37 amino acids with structural homology to salmon calcitonin. Co-localises with substance P in neurons. It occurs as a result of alternative processing of mRNA from the calcitonin gene. The neuropeptide is widely distributed in neural tissue of the brain, gut, perivascular nerves, and other tissue. The peptide produces multiple biological effects and has both circulatory and neurotransmitter modes of action. In particular, it is a potent endogenous vasodilator. Intracerebral administration leads to a rise in noradrenergic sympathetic outflow, a rise in blood pressure and a fall in gastric secretion. Acronym: CGRP (05 May 2002) |
| cancer susceptibility gene | tumour suppressor gene |
| rab gene | 1. <molecular biology> One of the three main groups of ras like genes specifying small GTP-binding proteins (the others are ras and rho). Rab proteins are involved in vesicular traffic and seem to control translocation from donor to acceptor membranes. 2. <cell biology> Gene family in plants responsive to abscisic acid: encode proteins of 15-17 kD. (18 Nov 1997) |
| pair rule gene | <molecular biology> A segmentation gene, expressed sequentially between gap genes and segment polarity genes. In development of Drosophila, a set of about 8 genes that are expressed only in alternate segments (odd or even) of the developing embryo. Loss of function mutants thus lack alternate segments. Examples: even skipped (eve), fushi tarazu (ftz), hairy. (18 Nov 1997) |