| chain reaction | A reaction in which a product reacts and thus continues the reaction. (09 Oct 1997) |
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| chain, orthodontic chain | <dentistry> A stretchable plastic chain used to hold archwires into brackets and to moke teeth. (08 Jan 1998) |
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| polymerase chain reaction | <molecular biology, technique> The first practical system for in vitro amplification of DNA and as such one of the most important recent developments in molecular biology. Two synthetic oligonucleotide primers, which are complementary to two regions of the target DNA (one for each strand) to be amplified, are added to the target DNA (that need not be pure), in the presence of excess deoxynucleotides and Taq polymerase, a heat stable DNA polymerase. In a series (typically 30) of temperature cycles, the target DNA is repeatedly denatured (around 90_C), annealed to the primers (typically at 50-60_C) and a daughter strand extended from the primers (72_C). As the daughter strands themselves act as templates for subsequent cycles, DNA fragments matching both primers are amplified exponentially, rather than linearly. The original DNA need thus be neither pure nor abundant and the polymerase chain reaction has accordingly become widely used not only in research, but in clinical diagnostics and forensic science. Acronym: PCR (14 Oct 1997) |
| A chain | A polypeptide component of insulin containing 21 amino acyl residues, beginning with a glycyl residue (NH2-terminus); insulin is formed by the linkage of an A chain to a B chain by two disulfide bonds; the amino-acid composition of the A chain is a function of species. Synonym: glycyl chain. In general, one of the polypeptides in a multiprotein complex. (05 Mar 2000) |
| alpha chain disease | A vague or indefinite term; could be used for alpha-heavy-chain disease (a lymphoplasma cell proliferative disease usually seen in Mediterranean men, characterised by intestinal involvement with steatorrhoea, often progressive with fatal outcome) or a thalassaemia (a genetic abnormality in the alpha globin chain of haemoglobin). (05 Mar 2000) |
| amino acids, branched-chain | Amino acids which have a branched carbon chain. (12 Dec 1998) |
| B chain | A polypeptide component of insulin containing 30 amino acyl residues, beginning with a phenylalanyl residue (NH2-terminus); insulin is formed by the linkage of a B chain to an A chain by two disulfide bonds; the amino-acid composition of the B chain is a function of species. Synonym: phenylalanyl chain. (05 Mar 2000) |
| behaviour chain | Related behaviours in a series in which each response serves as a stimulus for the next response. (05 Mar 2000) |
| branched chain acyl-CoA oxidase | <enzyme> Enzyme from human liver peroxisomes acts on both 2-methyl branched fatty acyl- and bile acid-CoA intermediates, unlike rat liver peroxisomes which have separate enzymes for branched chain fatty acids (pristanoyl-CoA) and bile acid-CoA; involved in beta-oxidation of fatty acids and bil Registry number: EC 1.3.3.- Synonym: 2-methyl-branched chain acyl-CoA oxidase, hbrcacox (26 Jun 1999) |
| branched-chain fatty-acid-kinase | <enzyme> From anaerobic spirochete ma-2 Registry number: EC 2.7.2.14 Synonym: isovalerate kinase, 2-methylbutyrate kinase, isobutyrate kinase (26 Jun 1999) |
| branched-chain fatty acid synthetase | <enzyme> Analogous to fatty acid synthetase complex but starting with a branched chain keto acid; from bacillis subtilis Registry number: EC 2.3.1.- Synonym: bcfa synthetase (26 Jun 1999) |
| branched chain ketoaciduria | Hereditary disease due to deficiency of an enzyme involved in amino acid metabolism, characterised by urine that smells like maple syrup. (12 Dec 1998) |
| branched chain ketonuria | Hereditary disease due to deficiency of an enzyme involved in amino acid metabolism, characterised by urine that smells like maple syrup. (12 Dec 1998) |
| gene rearrangement, alpha-chain T-cell antigen receptor | Ordered rearrangement of T-cell variable gene regions coding for the alpha-chain of antigen receptors. (12 Dec 1998) |
| gene rearrangement, beta-chain T-cell antigen receptor | Ordered rearrangement of T-cell variable gene regions coding for the beta-chain of antigen receptors. (12 Dec 1998) |
| gene rearrangement, b-lymphocyte, heavy chain | Ordered rearrangement of b-lymphocyte variable gene regions thereby contributing to antibody diversity. It occurs during the first stage of differentiation of the immature b-lymphocyte. (12 Dec 1998) |