00:01
Very classic genetics today.
00:02
We are going to look at fruit flies and their eye color.
00:06
So we are told that a certain species of fruit flies can have red eyes or white eyes.
00:10
And we're told that this is x -linked.
00:13
It's a sex -linked chromosome.
00:15
Or sorry, sex -linked allele.
00:18
And red eyes is dominant, whereas white eyes is recessive.
00:24
So something to note real quick when we're talking about x -linked traits is that males only have one x -chromosome.
00:36
So whichever one they have, if the male's one x chromosome is dominant red eyes, then that male will have red eyes.
00:48
If the male's one x chromosome is recessive for white eyes, then they will have white eyes.
00:54
Whereas the female has two x chromosomes.
00:58
So in order for the female to have white eyes, both of her x chromosomes must be recessive white.
01:04
All right, so we're going to look at a cross between a red -eyed male and a red -eyed female, and we're told that all of their female offspring have red eyes, but only some of their male offspring have red eyes.
01:20
The others have white eyes...