Question

A calico cat has a litter of 8 kittens: 1 yellow male, 2 black males, 2 yellow females, and 3 calico females. What are the genotypes for all the cats?

Answer 1

We need to know the father's genotypes for coat color as well to know that.

Answer 2

The calico mother is heterozygous for yellow and black, as explained in your other question about the sex of the yellow kitten. We know that Dad gives a Y chromosome to all the male kittens. The only question is whether the X chromosome he gave to all the female kittens has a Yellow allele or a Black allele.

You know has to be a yellow allele because some of the females (those that got the Yellow allele X from Mom as well) are yellow and the others (those that got the other possible female combination - a Black allele X from mom) have the heterozygous calico phenotype.

Clear?

Answer 3

Wait, so we don't need to know the father's genotypes? And what OTHER QUESTION are you talking about??

Answer 4

Yes, we need to know the father's genotype. One of the chromosomes is a Y which he gives to all the male kittens. The other is an X with a yellow allele on it which he gives to all the female kittens.

I explained about X inactivation in this response to the asker's other question: http://openstudy.com/study#/updates/4f31ec25e4b0c0e47961706c.

Answer 5

Okay...?

Answer 6

What exactly is calico?

Answer 7

Calico is a mixed phenotype. It happens when female cats have two X chromosomes, one with a yellow allele on it and one with a black allele on it. Because no cell can have two active X chromosomes in it (or it will die), one of the two is "inactivated" at random and none of the genes on it are expressed.

When the chromosome left active has a yellow allele, that particular hair will be yellow. When the chromosome left active has a black allele on it, that particular hair will be black. The mixed appearance is called calico.

Was that not clear in my answer to the other question?

Answer 8

Um... I hadn't looked yet, sorry.