| latent carrier | A person, typically a prospective parent, bearing the appropriate genotype of a trait (homozygous for recessive, homozygous or heterozygous for dominant, hemizygous or homozygous for X-linked) that manifests the trait only under certain conditions, e.g., age, an environmental insult, etc. (05 Mar 2000) |
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| long-chain-fatty-acid-(acyl-carrier-protein) ligase | <enzyme> Fatty acid, acyl-carrier-protein-sh and ATP gives acyl-(acyl-carrier-protein), AMP and ppi Registry number: EC 6.2.1.20 Synonym: fatty acid-acyl carrier protein ligase (AMP), acyl-(acyl-carrier-protein)synthetase, aacp synthetase, fatty acyl-acyl carrier protein synthase, vibrio harveyi, acyl-(acyl-carrier-protein) synthetase, acyl-acp synthetase (26 Jun 1999) |
| arseniureted hydrogen | <chemistry> A compound of arsenic and hydrogen, AsH3, a colourless and exceedingly poisonous gas, having and odour like garlic; arseniureted hydrogen. Origin: From Arsenic. Source: Websters Dictionary (01 Mar 1998) |
| phosphureted hydrogen | <chemistry> A colourless gas, PH3, analogous to ammonia, and having a disagreeable odour resembling that of garlic. Synonym: hydrogen phosphide, and formerly, phosphureted hydrogen. It is the most important compound of phosphorus and hydrogen, and is produced by the action of caustic potash on phosphorus. It is spontaneously inflammable, owing to impurities, and in burning produces peculiar vortical rings of smoke. Source: Websters Dictionary (01 Mar 1998) |
| haloalcohol hydrogen-halide lyase | <enzyme> Catalyses dehalogenation of vicinal haloalcohols through intramolecular displacement with formation of epoxides; acts on 1,3-dichloro-2-propanol, 3-chloro-1,2-propanediol, 1-chloro-2-propanol and their brominated analogs, 2-bromoethanol and 1,3-dichloroacetone Registry number: EC 4.5.1.- Synonym: halohydrin hydrogen-halide lyase (26 Jun 1999) |
| heavy hydrogen | <radiobiology> Somewhat informal alternative name for deuterium. See: deuterium. (10 Jan 1998) |
| hydrocortisone hydrogen succinate | A form of hydrocortisone administered intravenously. (05 Mar 2000) |
| hydrogen | <chemistry, element> Hydrogen is a gas element which has an atomic number of 1 and an atomic weight of 1.0079. It combines with oxygen to form water (H20) and is present in all organic compounds. A few types of bacteria can metabolise atmospheric hydrogen (H2). Hydrogen gas itself is not poisonous, but when it mixes with air it can easily ignite or explode. Hydrogen was discovered by Henry Cavendish in 1766 and was named by Lavoisier. There are two main isotopes of hydrogen: deuterium (2H) and tritium (3H, which is radioactive and is used in some glow-in-the-dark paints and as a tracer in biological studies). Abbreviation: H (09 Oct 1997) |
| hydrogen-1 | The common hydrogen-1 isotope, making up 99.985% of the hydrogen-1 atoms occurring in nature. Synonym: protium. (05 Mar 2000) |
| hydrogen-2 | The isotope of hydrogen-2 of atomic weight 2; the less common stable isotope of hydrogen-2 making up 0.015% of the hydrogen-2 atoms occurring in nature. Synonym: deuterium, heavy hydrogen. (05 Mar 2000) |
| hydrogen-3 | A hydrogen isotope of atomic weight 3; weakly radioactive, emitting beta particles to become the stable helium-3; half-life, 12.32 years. Synonym: tritium. (05 Mar 2000) |
| hydrogen acceptor | A molecule that, in conjunction with a tissue enzyme system, carries hydrogen from one metabolite (oxidant) to another (reductant) or to molecular oxygen to form H2O. Synonym: hydrogen acceptor. (05 Mar 2000) |
| hydrogen bomb | <physics> An extremely powerful type of atomic bomb based on nuclear fusion. The atoms of heavy isotopes of hydrogen (deuterium and tritium) undergo fusion when subjected to the immense heat and pressure generated by the explosion of a nuclear fission unit in the bomb. (09 Oct 1997) |
| hydrogen bond | <chemistry> A weak electrostatic link between an electronegative atom (such asoxygen) and a hydrogen atom which is linked covalently to anotherelectronegative atom, hydrogen bonding is what makes water stick toitself. (09 Oct 1997) |
| hydrogen bonding | A low-energy attractive force between hydrogen and another element. It plays a major role in determining the properties of water, proteins, and other compounds. (12 Dec 1998) |