genotype /jē″nōtīp′/ [Gk, genos, birth, typos, mark] , 1. the complete genetic constitution of an organism or group, as determined by the specific combination and location of the genes on the chromosomes. 2. the alleles situated at one or more sites on homologous chromosomes. A pair of alleles is usually designated by letters or symbols, such as AA when the alleles are identical and Aa when they are different. 3. a group or class of organisms having the same genetic makeup; the type species of a genus. Compare phenotype. −genotypic, adj.
