Which factor is true about epistasis?

Which factor is true about epistasis?

• A. An interaction between alleles at different loci on the same chromosome (can inhibit expression)
• B. Epistasis occurs only within a single locus
• C. Epistasis always enhances expression of all genes
• D. Epistasis means there is no genetic interaction

Answer: (A)

Epistasis is when the effect of a gene at one locus depends on the genotype at another locus, so the final phenotype results from interactions between genes rather than just additive effects at a single site. This inter-locus interaction can block or modify the expression of downstream genes, meaning one epistatic allele can inhibit the visibility of another gene’s effect. The statement presented captures this idea by describing an interaction between alleles at different loci that can inhibit expression. It’s worth noting that epistasis isn’t limited to genes on the same chromosome, and it doesn’t always boost expression—some interactions suppress or alter the phenotype instead. There is indeed a genetic interaction when epistasis is involved.

Epistasis is when the effect of a gene at one locus depends on the genotype at another locus, so the final phenotype results from interactions between genes rather than just additive effects at a single site. This inter-locus interaction can block or modify the expression of downstream genes, meaning one epistatic allele can inhibit the visibility of another gene’s effect. The statement presented captures this idea by describing an interaction between alleles at different loci that can inhibit expression. It’s worth noting that epistasis isn’t limited to genes on the same chromosome, and it doesn’t always boost expression—some interactions suppress or alter the phenotype instead. There is indeed a genetic interaction when epistasis is involved.