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

What genetic principle is the basis of this expected F₂ ratio?

Key Concepts

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, the expected phenotypic ratio in the F₂ generation is 9:3:3:1, assuming independent assortment of the genes. This ratio arises from the combination of alleles from both parents, illustrating Mendel's laws of inheritance.

Epistasis

Epistasis occurs when the expression of one gene is affected by one or more other genes, leading to a modification of expected phenotypic ratios. In cases of epistatic interactions, the presence of certain alleles can mask or alter the effects of alleles at another locus, resulting in ratios that deviate from the typical Mendelian expectations, such as the 9:3:3:1 ratio.

Mendel's Laws of Inheritance

Mendel's laws, particularly the law of segregation and the law of independent assortment, form the foundation of classical genetics. The law of segregation states that allele pairs separate during gamete formation, while the law of independent assortment states that genes for different traits are inherited independently. These principles help explain the expected ratios in dihybrid crosses, which can be altered by interactions like epistasis.