Dihybrid Cross: 9:3:3:1 Ratio

Genes and Alleles

A dihybrid cross tracks two genes, each with two alleles:

• Gene 1: de>A (dominant) / de>a (recessive)
• Gene 2: de>B (dominant) / de>b (recessive)

Parental Cross

de>AABB × aabb → F1 all de>AaBb (double heterozygous)

F1 Self Cross

de>AaBb × AaBb

Each parent produces four gametes: de>AB, de>Ab, de>aB, de>ab