What do we call the term used when two alleles of a gene are different?

When two alleles of a gene are different, the term used to describe this condition is "heterozygous." In genetics, each individual receives one allele from each parent, and when these two alleles are not the same, the genotype is classified as heterozygous. This variation can lead to a range of traits expressed in an organism, as different alleles may convey different characteristics.

In contrast, when both alleles in a pair are the same, the term is "homozygous." The other options refer to different concepts in genetics: "polygenic" pertains to traits that are influenced by multiple genes, and "genotypic" refers to the genetic constitution of an organism, encompassing all alleles rather than specifically addressing their similarity or difference. Understanding these distinctions is crucial for interpreting genetic information and traits accurately.