dominant gene In diploid organisms, a gene that produces the same phenotypic character when its alleles are present in a single dose (heterozygous) per nucleus as it does in a double dose (homozygous). For example, if A is dominant over a, then AA (the homozygote) and Aa (the heterozygote) have the same phenotype. A gene that is masked in the presence of its dominant allele in the heterozygote state is said to be recessive to that dominant. Such a dominance-recessive relationship is common between two alleles, the gene most frequently present at a given locus being usually dominant to its alleles.

dominant gene In diploid organisms, a gene that produces the same phenotypic character when its alleles are present in a single dose (heterozygous) per nucleus as it does in double dose (homozygous). For example, if A is dominant over a, then AA (the homozygote) and Aa (the heterozygote) have the same phenotype. A gene that is masked in the presence of its dominant allele in the heterozygote state is said to be recessive to that dominant. Such a dominant–recessive relationship is common between two alleles, the gene most frequently present at a given locus being usually dominant to its alleles.