Question: what is the difference between a heterozygous and homozygous genotype?
Answer: A heterozygous individual is someone who has two different alleles at a locus. For instance, using the sickle cell example, a heterozygous individual might have a genotype of AS. A homozygous individual has two identical alleles at a locus. The genotype for a homozygous individual might be AA or SS.