One gene masks or modifies the expression of another gene at a different locus.
Epistasis is an interaction between genes where one masks the effect of another. In Labrador retrievers, the E gene (pigment deposition) is epistatic to the B gene (black versus brown); ee dogs are yellow whatever the B genotype. Ratios become 9:3:4 or 12:3:1.
It is typically revealed by modified dihybrid ratios.
One gene masks or modifies the expression of another gene at a different locus.
Epistasis is one of the 54 topics in Genetics. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Dihybrid Cross, Law of Independent Assortment, X-Chromosome Inactivation.
The Bombay phenotype hides ABO type because of a gene needed to make H antigen.
Work through the Beginner topics in Genetics first, such as Heredity, Gene, Allele, then return to Epistasis. Intermediate topics assume the Beginner vocabulary.
The closest topics to Epistasis are Dihybrid Cross, Law of Independent Assortment, X-Chromosome Inactivation, Dominant and Recessive. Comparing them side by side is a good way to see how the ideas connect.
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Epistasis. To practise the whole of Genetics, use the Genetics quiz.
Epistasis: One gene masks or modifies the expression of another gene at a different locus. Dihybrid Cross: A cross following two genes at once, giving a 9:3:3:1 phenotype ratio when genes assort independently. Read both side by side and note what each one explains.
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Dihybrid Cross and explain the difference aloud. Finally, take the Genetics quiz and come back to this page for any question you miss.
A cross following two genes at once, giving a 9:3:3:1 phenotype ratio when genes assort independently.
🧬 GeneticsAlleles of different genes are distributed to gametes independently when the genes lie on separate chromosomes.
🧬 GeneticsOne X chromosome in each female cell is silenced as a Barr body to equalise gene dosage.
🧬 GeneticsA dominant allele shows its effect when present in one copy; a recessive allele only shows when two copies are present.
🧬 Genetics