heterozygote(redirected from Heterozygotes)
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heterozygote(hĕt'ərōzī`gōt): see geneticsgenetics,
scientific study of the mechanism of heredity. While Gregor Mendel first presented his findings on the statistical laws governing the transmission of certain traits from generation to generation in 1856, it was not until the discovery and detailed study of the
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a cell or organism having in its hereditary set (genotype) different forms (alleles) of a given gene.
A heterozygote is the result of the union of gametes of different genetic composition, each of which brings its own alleles to the zygote. For example, homozygous types AA and aa form gametes A and a respectively. The heterozygote obtained by the hybridization of AA and aa always forms mixed gametes (A and a). Crossing this type with itself or with the recessive parental type aa produces offspring of two types—phenotypic A and phenotypic a. The splitting of the heterozygote proceeds according to Mendel’s law. The preservation of the heterozygote is of significance in agriculture, since splitting often leads to the loss of valuable qualities. Almost all fruit trees are heterozygous; in order to avert splitting and the loss of valuable traits, they are bred by vegetative reproduction, apomixis, gynogenesis, or parthenogenesis.
IU. S. DEMIN