∞ generated and posted on 2016.12.15 ∞

Diploid individual that possess two different alleles at the same locus on two otherwise equivalent chromosomes.

Heterozygote 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 Heterozygotes, are not identical to each other, either genotypically or, as is the case in practice with Mendelian genetics, phenotypically.

For example, AB, AO, BO, and Rr all would represent heterozygotes. They are formed when each parent contributes a different allele to their offspring, which is possible only if more than one allele at a given locus exists within a population, that is, only if polymorphisms either are present or have been mutationally generated. See by contrast homozygote. See too Mendelian genetics.

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.

The following video discusses the above figure:

Note that with the heterozygous condition comes the potential for various dominant-recessive phenotypic relationships between alleles but also, in certain instances, a potential for greater abilities due to possessing different alleles that display slight differences in functionality, that is, which together can give rise to what is known as a hybrid vigor.

See also the concept of heterozygosity.