Question

What is the probability that the first offspring from the cross listed below will be heterozygous for all loci?

Answer 1

Answer and Explanation:

Cross: aa Bb dd Ee x AA bb Dd Ee

We can calculate the probability of getting heterozygous individuals in the progeny by using the product rule. Assuming that these four genes assort independently (events that occur independently from each other), we can infer that the F1 will have the next genotypic proportions for each gene:

1) aa     x     AA

F1) 4/4=1 Aa

2) Bb    x    bb

F1) ½ bb

     ½ Bb

3) dd    x    Dd

F1) ½ dd

     ½ Dd

4) Ee    x    Ee

F1) ¼ EE

    2/4 = ½ Ee

     ¼ ee

So, to know what the probability is that the F1 of being heterozygous for all loci, we must multiply the respective individual probabilities of getting a heterozygous genotype, like this:  

1 Aa   x   ½ Bb   x    ½ Dd    x    ½ Ee = 1/8 AaBbDdEe