In a dihybrid cross, we are examining two traits at the same time, which means each parent will contribute two alleles per trait. If we assume that the traits are governed by two different genes that each have two alleles, say A/a for the first gene and B/b for the second gene, then each parent can produce a variety of combinations of alleles.
To explore this a bit deeper, let’s break down the alleles: one parent with the genotype AaBb can produce gametes with the following combinations of alleles:
- AB
- Ab
- aB
- ab
This results in a total of 4 different combinations of alleles from one parent (2 from the first gene and 2 from the second gene). Therefore, when creating a Punnett square for a dihybrid cross, there are 4 different options for the alleles from one parent.