Epistatic gene interaction results in a modification of the F₂ dihybrid ratio.

What is the expected F₂ ratio?

Key Concepts

Epistasis

Epistasis refers to the interaction between genes where the expression of one gene is affected by one or more other genes. This can lead to modifications in phenotypic ratios, particularly in dihybrid crosses, where the expected Mendelian ratios may not occur due to the masking or altering effects of epistatic genes.

Dihybrid Cross

A dihybrid cross involves two traits, each controlled by different genes, typically represented by two pairs of alleles. In a standard dihybrid cross of heterozygous individuals (AaBb x AaBb), the expected phenotypic ratio in the F₂ generation is 9:3:3:1. However, epistatic interactions can alter this ratio, leading to different expected outcomes.

F₂ Generation

The F₂ generation is the second filial generation, produced by crossing individuals from the F1 generation. In genetic studies, analyzing the F₂ generation helps in understanding inheritance patterns and the effects of gene interactions, such as epistasis, which can significantly change the expected phenotypic ratios derived from Mendelian genetics.