00:01
Okay, in order to answer this question, we have to talk about a codominance.
00:04
Remember that in codominance, both phenotypes are going to be present.
00:08
For example, in this case, we have two alleles.
00:10
We have the xb allele and the xr allele.
00:13
The xb allele is the allele for black furor, okay? and for black code and the xr is the allele for orange code allele.
00:33
Okay, so let's talk about females.
00:37
In female cats, you can have xb, xb, and this is going to be a black cat.
00:43
You can also have xr, xr, and this is going to be an orange cat, female cat, obviously, because it is xx.
00:52
And when you have xb, xr, it is going to be a calico.
00:58
Obviously, all of them are females.
01:01
And this is codominance because when the xb and the xr are present, and it is a calico, and the b is not going to be dominant over this r, but both the orange and the black are going to be present.
01:15
The orange and the black phenotypes are going to be present in one organism, okay, in one cat.
01:21
And for males, we're going to have x, b, y, that is going to be a black cat, and x r y, that is going to be an orange cat.
01:32
This is going to be for males.
01:33
As males only have normally, only have one chromosome, then they are not going to be.
01:38
Able to be calico, never, okay? because they only have one chromosome.
01:43
There are some exceptions, but they are not, they are not like physiologic.
01:46
It means they are like pathologics.
01:49
But we're not going to talk about that right now.
01:51
The question says, show the cross of a female calico card with a black male.
01:58
So question number one says to cross a female calico card, well, when they tell you calico, it is obvious that it is a female, okay? so xvxr cross with a black male.
02:09
So we have this.
02:12
We just have to make a panel square like this, and we're going to get xb, xb, xb, xb, x, x, r, xby, and xry.
02:27
Okay, so this is what we're going to get.
02:30
Question number two says, says what percentage percentage? they're asking us for a percentage of that kiddens will be black and male.
02:39
So we want males.
02:40
So we're going to take only these ones here because they are going to be xy and xy.
02:44
So out of two, because this is one possibility, the second possibility, out of two, only one is going to be black.
02:51
So one half.
02:53
One half, you can divide it one by two and you're going to get 0 .25.
02:57
And in order to make this a percentage, you have to multiply by 100 and you're going to get 50%.
03:04
So this is the answer for question number two.
03:06
Okay, this is the percentage of for the kittens that are going to be black and maids.
03:13
Question number three asks, what percentage of the kidneys will be calico in male? well, this is obviously zero because male cats cannot be calico.
03:26
As we stated here, because normally, physiologically, males only have one chromosome, so they are never, normally they are never going to be calico.
03:35
There is one exception, as i already said before.
03:39
That is when this cat, when a male cat has clean a filter, syndrome...