00:02
Hi there, in fruit flies, eye color is a sex -link trait, and it's carried on the x chromosome.
00:09
So red is the dominant, known as the wild type.
00:13
So to code for a red, it's carried on the x chromosome.
00:20
So the capital r will represent red.
00:23
So this would be a red allele.
00:25
And then the recessive, the little r, would code for y dots.
00:30
And then, of course, the y chromosome does not carry an allele for eye color.
00:38
So in this question, we are crossing a white -eyed male and a heterozygous red -eyed female.
00:47
All right.
00:48
So our female is heterozygous for red eyes.
00:52
So that means she's going to carry one of each allele.
00:57
X capital r, x little r.
01:00
And we are crossing her with our male.
01:05
Who has white eyes.
01:07
So that means he's going to be xy, so that means his only x allele has to be the recessive for white eye color.
01:16
Okay, so this is our cross.
01:18
So we want to make a punnet square to predict our offspring.
01:30
All right, so our female gametes, the eggs, they will carry one of these two alleles, either x capital r or x little those are the two types of eggs the female could make.
01:45
The male can make sperm that is x little r or y...