00:01
In order to answer this question, let's talk about inheritance.
00:03
This question says, the following pedigree illustrates the inheritance of dmd, the chain muscular dystrophy, a condition characterized by progressive weakness, and the generation of skeletal muscles due to the absence of dystrophy.
00:15
And you have this pedigree.
00:17
And it says, on the basis of this pedigree, what do you think is the most likely mode of inheritance for the chin muscular dystrophy? so in this case, as you can see here, you have affected individuals, and these individuals have healthy parents.
00:31
So remember that when you have an inherited disease, if this male offspring here are affected by the disease, it means that they have the mutagenalil.
00:40
And if they have the mutagenalil, it means that at least one of the parents gave them the mutagenalil.
00:46
But both parents are healthy.
00:48
So it means that both parents are cagers, and you don't have caggers in dominant disease.
00:52
So this pedigree is not exling dominant or autosomal dominant.
00:57
This can be autosomal gilder.
00:58
Or ex -ling recessive.
01:00
Now, in this case, what is very, what you can see here very clear is that only males are affected.
01:09
And when you have that only males are affected in this pedigree, it means that it is very likely that this is an ex -link decisive disorder.
01:24
Why? because remember that if it is an ex -link condition, females require two recessive ades.
01:30
Let's use the d gene.
01:34
Females require two excessive alleles in order to express a disease, while males require only one mutant allele in order to express the disease.
01:42
So it is easier for males to get the disease because they only require one mutative allele to express a disease because they have only one chromosome.
01:51
While in females, you need both alleles to be mutated in order to express a disease, and this is very unlikely to happen because most of the people affected are going to have, are going to die before the age of 30.
02:05
So this is why it is an excellent disease.
02:08
And it says, if couple, three, seven, it means in one, two, three, four, five, six, and seven, this one, seven and eight, have another child, what is the probability that a child will have to chin muscular dystrophy? so in this case, remember that for d and d, when you have the homozygous domino, or the heterocygous in females, you're going to have a normal female, and in males, this is going to be for a normal male.
02:35
And in case of dmd, this is going to be the genotype for a woman with dmd.
02:39
And this is going to be the genotype for a man with dmd.
02:42
So in this case, this man is affected.
02:46
And the same for this man here.
02:48
And in this case, the father is healthy.
02:51
And remember that the person in here is one allele from his parent.
02:54
In this case, the y chromosome always comes from the father.
02:57
And the excessive the allele or the x chromosome is coming from the mother.
03:00
But the mother is not affected.
03:02
Means that the mother should be a carrier like this.
03:07
So in this case what happened is that the father transmitted the y chromosome here and this was a ciparil came from from the mother.
03:14
So it says what is the probability that the child will have a dmd, another child from this cross.
03:21
So you have the heterozygibose with this one here and you get here the homozylus dominant, the hyderocygose, this one, and this one.
03:37
So the probability that the child, they are including both sons and daughters, okay? so out of four possibilities, how many of them are going to have dmd? you have that out of four only one, that is this one here.
03:50
So you have one quarter, and one quarter is the same as 0 .25 or 25%.
03:55
So the answer here is 25%.
03:58
The last question says, if 3 -2 and 3 -7, it means this man here and 3 -7 is this one here.
04:07
So these two people made it, what is the probability that one of their children would have a disease? so in this case, this man is like this.
04:18
So let's do that cross.
04:20
You have a hetero cytopos here with this one here, and you have hetero cycles for more cycle of excessive, with this and this.
04:33
So they are asking you the chance that one of the children will have a disease.
04:36
You have the total of four possibilities.
04:39
One and two are going to be affected by the disease.
04:42
So in this case, you have two quarters that is the same as one half or 0 .5 or 50%.
04:47
So the answer for this question is 0 .5 or 50%.
04:51
And this is the answer for this part of the question.
04:54
The next question says, we have the following.
04:57
It says, consider that the pedigree diagram of phenotypes below.
05:02
So we have this pedigree here.
05:03
And it says, assuming that the shaded individuals have an autosomal recessive rate count the individuals with and you have this.
05:09
So in this case, if this is an autosomal recessive condition, when you have the homocyco -resensive you're going to have the disease, and the homocybinolicyles dominant and the heterocygous and are going to be normal.
05:22
Okay, so in this case this woman is affected also this woman, also this woman, this woman, and that's it.
05:30
Now remember that the first song in here is one all right from each parent.
05:32
In this case, this woman has two recessive aides.
05:35
It means that one excessive a came from the father and one came from the mother.
05:39
So both parents should be heterocygous because they are not affected.
05:43
Now, from a cross between a heterocygous with a heterozygous with a heterocygous, you have a following cross, where you can get homocygous dominant, heterozygos, heterozygos, and homozygos recessive.
05:54
So these three individuals here, or these four offspring actually, can be either homozygous domine or heterocygose.
06:01
So we cannot know their genotypes specifically...