Alleles are different versions of a gene that determine specific traits or characteristics in an organism. They can be dominant or recessive, and individuals inherit two alleles for each gene, one from each parent.
Related terms
Genotype: The genetic makeup of an organism, determined by the combination of alleles it possesses.
Dominant allele: An allele that is expressed and masks the presence of a recessive allele.
Recessive allele: An allele that is only expressed when two copies are present and no dominant allele is present.