00:01
Hi there.
00:02
In this question, we are told that black fur is caused by an x -linked allele.
00:08
So i'm going to do x chromosome with a b, and that is going to code for black fur.
00:17
Excuse me.
00:18
We're also told there's another allele at this locus that causes orange color, but that is not recessive because we see that when we have both of these, we get codominance, and we get the tortoise shell.
00:36
Or calico is they're called.
00:40
All right, so i'm going to give these two alleles, different letters, since they are co -dominant.
00:45
There's not a dominant and recessive one.
00:48
And we're told that we are crossing a female that has black fur.
00:56
That means she has to be xb, xb.
01:01
And a male that is orange.
01:05
Well, males only carry one x chromosome, so it's going to be x -o -y.
01:11
So this is our cross.
01:12
Let's go ahead and set up punnit square.
01:19
The female with the black fur can only produce one type of gamete...