Question

dihybrid crosses advanced mendelian genetics part i. sample problem. mendel identified that the following characteristics in pea plants follow dominant - recessive hereditary patterns: → yellow (y) peas are dominant to green (y) peas → round (r) peas are dominant to wrinkled (r) peas → purple flowers (p) are dominant to white (p) flowers in a dihybrid cross, the possibilities of offspring inheriting two different traits (such as pea color and shape of the peas) can be analyzed. this time the punnett square contains 16 squares. ex: cross 2 parents heterozygous for both pea color and pea shape. step 1. first, write out the parents genotypes. in this case, both parents have the same genotype: yyrr. step 2. next, write out the possible allele combinations that each parent could contribute to offspring. place these on the outside of the dihybrid punnett square. each parent can only give one allele for each trait just like in a regular punnett square. however, because you are looking at two traits simultaneously, there will be two alleles in each possible combination. there are 4 possible ways that the alleles can segregate: yr (possibility #1) yr (possibility #2) yr (possibility #3) yr (possibility #4) since both parents are identical, the possibilities from plant parent 2 are the same.

Explanation:

Step1: Identify parent genotypes

Both parents are YyRr.

Step2: Determine possible allele - combinations

Each parent can contribute YR, Yr, yR, yr.

Answer:

The parent genotypes are YyRr for both, and the possible allele - combinations each parent can contribute are YR, Yr, yR, yr.