Posted by stew on .
need help with these genetics problems. please help with what you can. thanks:
Given that loci A and B in Drosophila are sexlinked and 20 map units apart, what phenotypic frequencies would you expect in male and female offspring resulting from the following crosses? (Assume A and B are dominant to a and b, respectively).
A) AaBb (cis) female X ab/Y male
B) AaBb (trans) X ab/Y male
C) aabb female X AB/Y male
Question 2:
Assume that a cross is made beyween AaBb and aabb plants, and the offspring occur in the following numbers: 106 AaBb, 48 Aabb, 52 aaBb, 94 aabb. These results are consistent with which arrangement of genes?

genetics 
Anonymous,
jkn

genetics 
Esha,
for 2a  cis means the AB is paired on the same chromosome and the ab is on the other. you would expect 80% females AB/ab and 20% females ab/ab. For males, 80% AB/Y and 20% ab/Y.
2b use the same logic as 2a, expect now the chromosomes are Ab and aB to start.
for 2c  it is all AB/ab females and all ab/Y males.