Question

How does the relationship between dominant and recessive alleles of a gene differ from epistasis?

Short answer

Dominant/recessive alleles pertain to interactions of alleles within the same gene, where dominant alleles mask the effects of recessive ones. Epistasis pertains to interactions between different genes, where the effect of one gene can suppress or mask the effect of another gene.

Step-by-step solution

Dominant and recessive alleles

These are different versions of the same gene. An individual with one dominant and one recessive allele for a certain trait will express the trait associated with the dominant allele. The dominant allele is represented by a capital letter (A), and the recessive allele by a lowercase letter (a). So, if an individual has 'Aa' or 'AA' alleles, they will express the trait associated with the dominant 'A' allele. The recessive trait will only be expressed when there are two recessive alleles, 'aa'.

Epistasis

Epistasis is a phenomenon in genetics where the effect of one gene is dependent on the presence of one or more 'modifier genes'. Usually one gene interfere with the expression of another gene, often masking its effect. suppose, the gene A is epistatic to the gene B. Here, the gene A has the dominant effect and can mask the effect of gene B.

Comparison

In the case of dominant and recessive alleles, one allele masks the effect of another allele of the same gene. Whereas in Epistasis, one gene can mask the effect of another gene. Also, dominance/recessiveness is about the interaction of two alleles of same gene, while epistasis is about interaction among different genes.