Genetics Day 2

Today, we took a quiz on mono-hybrid crosses then went over di-hybrid crosses. This occurs when there are 2 genes involved in the cross. Here is an example of a di-hybrid cross problem. A heterozygous running, heterozygous white fur rabbit crosses with a homozygous running, homozygous brown fur rabbit. Determine the genotypic ratios. R = running r = waltzing. W = white w= brown. 

First, you can use Dr. Fitz's or Mr. Quick's way.

Here is Mr. Quick's way:

Then, you take each square from the left and combine them with all four from the right.

RRWw RRWw RRww RRww

RRWw RRWw RRww RRww

RrWw RrWw Rrww Rrww

RrWw RrWw Rrww Rrww

So the genotypic ratios would be:

4 RRWw : 4 RRww : 4 RrWw : 4 Rrww

Or 1:1:1:1

That was all for the di-hybrid cross class.