Epistasis

Definition

Epistasis is a genetic interaction where one gene affects the expression of another gene. It can modify phenotypic ratios expected from Mendelian inheritance patterns.

5 Must Know Facts For Your Next Test

1. Epistasis can cause deviations from the classic 9:3:3:1 ratio seen in dihybrid crosses.
2. Recessive epistasis occurs when the recessive allele of one gene masks the effects of either allele of another gene.
3. Dominant epistasis occurs when a dominant allele of one gene masks the effects of either allele of another gene.
4. An example of epistasis is coat color in Labrador retrievers, where one gene determines pigment color and another controls pigment deposition.
5. Understanding epistasis is crucial for studying complex traits and polygenic inheritance.

Review Questions

• What effect does epistasis have on Mendelian inheritance ratios?
• Can you give an example of how epistasis works in a real-world scenario?
• How do recessive and dominant epistasis differ?

Related terms

Allele:

A variant form of a gene.

Polygenic Inheritance: Inheritance pattern controlled by two or more genes.

Phenotype: The observable characteristics or traits of an organism.