What do we call an organism that has two different alleles for a particular gene?

An organism that has two different alleles for a particular gene is referred to as heterozygous. This term indicates that the two alleles at a specific locus on homologous chromosomes are different from one another, which can lead to a variety of trait expressions depending on the dominance relationships of those alleles.

For instance, if one allele codes for a particular trait, such as flower color, and the other allele codes for a different color, the phenotype exhibited by the organism will depend on which allele is dominant. Heterozygosity is significant in genetics because it introduces genetic diversity and can impact an organism’s ability to adapt to various environmental pressures.

In contrast, homozygous describes an organism that has identical alleles for a given gene, while hemizygous refers to having only one allele for a particular gene, typically observed in sex-linked traits in males of species with sex chromosomes. Genotype is the overall genetic makeup of an organism, which includes both homozygous and heterozygous conditions but does not specifically refer to the scenario of having two different alleles.