How do homozygous alleles differ from heterozygous alleles?

Homozygous alleles are identical pairs of genes, while heterozygous alleles are different pairs of genes.

In genetics, an individual's traits are determined by the genes they inherit from their parents. These genes are located on chromosomes, and each trait is usually determined by a pair of genes, one from each parent. When these pairs of genes are identical, they are referred to as homozygous alleles. On the other hand, when the pairs of genes are different, they are known as heterozygous alleles.

Homozygous alleles can be either dominant or recessive. If an individual has two dominant alleles (for example, AA), they will express the dominant trait. Similarly, if an individual has two recessive alleles (for example, aa), they will express the recessive trait. In both cases, the individual is homozygous for that trait because the two alleles are the same.

In contrast, heterozygous alleles consist of one dominant and one recessive allele (for example, Aa). In this case, the individual will express the dominant trait, but they also carry the recessive trait, which can be passed on to their offspring. This is known as being heterozygous for that trait.

The difference between homozygous and heterozygous alleles is crucial in understanding how traits are inherited. In simple terms, being homozygous for a trait means having two of the same kind of gene for that trait, while being heterozygous means having two different kinds of genes. This difference can affect not only the traits an individual expresses, but also the traits they can potentially pass on to their offspring.