Homozygote

A homozygote's cells are diploid or polyploid and have the same alleles at a locus (position) on homologous chromosomes. When an organism is referred to as being homozygous for a specific gene, it means that it carries two identical copies of that gene for a given trait on the two corresponding chromosomes (e.g., the genotype is AA or aa). Such a cell or such an organism is called a homozygote.

A homozygous dominant genotype occurs when a particular locus has two copies of the dominant allele (e.g., AA). A homozygous recessive genotype occurs when a particular locus has two copies of the recessive allele (e.g., aa). This can occur when both parents carry at least one copy of the allele.