∞ generated and posted on 2016.12.15 ∞
Diploid individual that, at a specific, single locus, possesses two identical alleles.
| Homozygote refers to the alleles that are present at single location (locus) on two homologues, that is, equivalent chromosomes as found within the same, diploid individual. Specifically, those alleles, one found on each homologue, with Homozygotes, are identical to each other, either genotypically or, as is the case in practice with Mendelian genetics, phenotypically. |
In a homozygous individual the trait associated with the allele found at that locus will in most cases be expressed. See also homozygous recessive, homozygous dominant, and, more generally, Mendelian genetics. By contrast, see Heterozygote.
Figure legend: Homozygote (left) versus heterozygote (right). In both cases the individuals are diploid, but at the A locus the homozygote possess two copies of the A allele (one per chromosome) whereas the heterozygote, a.k.a., a monohybrid, possesses one copy of the A allele, on one chromosome, and one copy of the a allele at the other. Note that typically the terms homozygote and heterozygote are used to describe the situation for one locus at a time. That is, it is perfectly reasonable for an individual to be homozygous at one locus while at the same time heterozygous at a different locus. Indeed, an individual that is heterozygous at two loci of interest, at the same time, would be described as dihybrid, or for three different loci a trihybrid, etc.
Barring mutation, all of a homozygous individuals' offspring will possess that allele at that locus, though not necessarily also in a homozygous state. Such individuals as a consequence can be described as true breeding.