00:01
If we look at the information provided in these three crosses, we can determine quite a lot from the information provided.
00:12
So let's just write out the females were sickle, and i'm going to leave myself enough room to write the genotypes next to them, round and sickle, for each of the three crosses.
00:24
And the males were round, sickle, and oval.
00:31
And crosses between these yielded an f1 females that were sickle, sickle, and oval, and males that were sickle round and sickle.
00:54
If we take a look, the first two crosses are reciprocal crosses.
00:59
You have females with round and then round females with sickle males.
01:05
When you have the results in the f1 of reciprocal crosses that are different, so if we look, cross one produced females that were sickle, as did cross two, but the males in the f1 were different.
01:20
The first cross produced sickle males, the second cross produced round males.
01:25
That tells us that this gene is on the x chromosome.
01:30
And so then if we look again using cross one and cross two, the females are sickle in the f1 and it tells us that sickle is dominant to round.
01:45
And then if we use the information in three, a sickle female bread with an oval male, but you get oval females and sickle males, that tells you that oval is dominant to sickle.
01:57
So we have a dominance hierarchy of oval to sickle to round.
02:03
And so we can use w -o for oval, w -s for sickle, and w -r for round.
02:15
And so now i think we have enough information to determine the genotypes from part one.
02:22
So here, a sickle female would be w -s -w -s.
02:29
A round male would be w -r -y.
02:34
The offspring, you could do a monohy cross if you need to would be ws wr and the sickle male would be wsy...