遗传学名词解释 英文版遗传学名词解释 英文版.docVIP

遗传学名词解释 abortive transduction An event in which transducing DNA fails to be incorporated into the recipient chromosome. See transduction. accession number An identifying number or code assigned to a nucleotide or amino acid sequence for entry and cataloging in a database. acentric chromosome Chromosome or chromosome fragment with no centromere. acridine dyes A class of organic compounds that bind to DNA and intercalate into the double-stranded structure, producing local disruptions of base pairing. These disruptions result in nucleotide additions or deletions in the next round of replication. acrocentric chromosome Chromosome with the centromere located very close to one end. Human chromosomes 13, 14, 15, 21, and 22 are acrocentric. active site The substrate-binding site of an enzyme; in other proteins, the portion whose structural integrity is required for function. Adaptation A heritable component of the phenotype that confers an advantage in survival and reproductive success. The process by which organisms adapt to current environmental conditions. additive genes See polygenic inheritance. additive variance Genetic variance attributed to the substitution of one allele for another at a given locus. This variance can be used to predict the rate of response to phenotypic selection in quantitative traits. A-DNA An alternative form of right-handed, double-helical DNA. Its helix is more tightly coiled than the more common B-DNA, with 11 base pairs per full turn. In the A form, the bases in the helix are displaced laterally and tilted in relation to the longitudinal axis. It is not yet clear whether this form has biological significance. See B-DNA. albinism A condition caused by the lack of melanin production in the iris, hair, and skin. In humans, it is most often inherited as an autosomal recessive trait. Alkaptonuria An autosomal recessive condition in humans caused by lack of the enzyme homogentisic acid oxidase. Urine of homozygous individuals turns dark upon