How do homozygous alleles differ from heterozygous alleles?

Homozygous alleles are characterized by having two identical alleles for a specific gene, meaning that both copies of the gene inherited from each parent are the same. This can be either two dominant alleles or two recessive alleles (e.g., AA or aa). This uniformity in the genetic makeup for that particular trait leads to a consistent expression of that trait.

In contrast, heterozygous alleles consist of two different alleles for a specific gene, such as one dominant and one recessive allele (e.g., Aa). This variation can result in different phenotypes compared to homozygous individuals, depending on the dominance and interactions between the alleles.

Thus, the distinction lies in the identity of the alleles: homozygous means they are the same, while heterozygous means they are different. This understanding is fundamental in genetics, explaining how traits are inherited and expressed in organisms.