An Epistasis Problem?

Question

a. A male black Labrador retriever of genotype BbCc is mated with a female black Labrador retriever of genotype BbCc. what colors can thier offspring be?
b. In what % do you expect each of them to occur?

I have no idea how to do this!

Answer 1

Gene Allele Description
B=black, b=brown
C=color deposition, c= no color deposition

Parents cross: BbCc x BbCc
Gametes: BC; Bc; bC; bc x BC; Bc; bC; bc

F1 Punnnet Square

.........BC....Bc....bC....bc
BC

Bc

bC

bc

the result of the punnet square is as follow:

9/16 B_C_ Black (color deposition)
3/16 bbCC Brown (color deposition)
3/16 BBcc Yellow (no color deposition)
1/16 bbcc Yellow (no color deposition)

ratio: 9:3:4

gene c is epistatic on gene B/b

Answer 2

I saw a problem almost exactly like that one if you google "genetics problems" it is the first website you come to. Epistasis is when one trait masks the expression of another..for instance if you were supposed to have a 9:3:3:1 ratio, and it came out 9:3:4, it would be a case of epistasis, bc you see the phenotype of one thing such as the color black when you should be seeing another color... hope this makes sense

Answer 3

I must have been smoking too much pot. With Four different gametes each, then there is 16 possible outcomes, with BC being expressed the most often. (9:3:4) Dihybridized as in the mouse coat example listed here:

http://www.msstate.edu/dept/poultry/Lecture%205.pdf