How do you er... reverse a punnett square?

Question

I know how to do the normal one with like AB and aB and Aa and AA, but this one is like you have to use Foil from Algebra 1. That was last year! I don't remember all that well. The problem says cross an AAbb male with an aaBb female. How many different gametes can the female produce? what is the expected phenotypic ratio among the offspring? How many different phenotypes are possible among the offspring of this cross blah blah blah. Then there's the box thing. Please explain. I'm alittle lost

Thank U!!!

Answer 1

This will give you a 9:3:3:1 ratio - but maybe not in your case since not all your genes are heterozygous.

The male gamates are: Ab Ab bA bA

The female gamates are: aB ab Ba ba

So just get the female gamates and then do a 4 x 4 punnet square. Good luck!!

Answer 2

The basic solution to this problem is to first figure out the genotype of the female eggs and male sperm, and add them together. This problem isn't difficult at all since the sperm are genetically identical, while the eggs could have two possible genotypes.

For example, consider that the male is AaBB while the female is AABb.

Males sperm are AB or aB (we assume the genes aren't linked).
Female eggs are AB or Ab. So the possibilities are ABxAB, ABxAb, aBxAB, aBxAb. This gives genotypes of AABB, AABb, AaBB, AaBb, in a 1:1:1:1 ratio. Easy right? For your case it's even simpler, and it's a 1:1 ratio.