Question

3. Suppose that there are 4 genes, all known to be located on different chromosomes. In the following cross, what are the expected frequencies of the offspring with the following genotypes?

AaBBCcDd x AaBbCcdd

AABBCCdd
aaBBccDD
AaBBccDd
AaBbCcDd

Answer 1

d

Answer 2

You have to figure out the probabilities each genotype for each allele, then multiply them because each locus is independent.

For example, the probability distribution over Aa x Aa ---> 1/4 AA, 1/2 Aa and 1/4 aa.
The probability distribution over BB x Bb ---> 1/2 BB and 1/2 Bb.

Therefore, the probability of AABB (as in the first possible offspring) is 1/4 x 1/2 = 1/8.

Hope that is helpful.