who has hemophilia in the pedigree that is shown? This is a topic that many people are looking for. star-trek-voyager.net is a channel providing useful information about learning, life, digital marketing and online courses …. it will help you have an overview and solid multi-faceted knowledge . Today, star-trek-voyager.net would like to introduce to you Hemophilia genetics. Following along are instructions in the video below:
s consider the inheritance of haemophilia. Which is sex linked. But this could apply to to any sex linked condition it could apply to brut blue green colorblindness for example why this occurs is as you know if you want to reproduce.
You need x x. Which is a female and we need an x y lee. Which is a male.
But this arises because the x chromosome would just draw a diagram of the x chromosome. Its relatively large whereas. The y chromosome is a very small chromosome.
So this means if we have a gene that is on that part of the x chromosome. Thats fine that will work. But can you see theres no homologous position on the y chromosome.
Its too small whereas. If were dealing with a female and we have two x chromosomes. So thats x and y x.
In the female. There are two positions. So the female has two opportunities to have the gene present and this is the locus.
The position on the chromosome of the gene for example for producing factor. Eight factor eight is an essential clotting factor for the blood. Its an essential part of the coagulation cascade.
So without factor. Eight present the blood cannot clot properly now the gene for normal clotting in this case is dominant. The hemophilia gene is recessive so this means all you need is one copy of the normal dominant gene not to have any coagulation disorder.
Now this tends to arise. When we have a female whose x. Chromosome is carrying one normal dominant gene.
So well give that again that chromosome a capital h. But another x chromosome. Which is carrying the recessive hemophilia gene.
So we can see that this woman is x big h x small h.
Shes heterozygous for the humor. Philia gene this means should be phenotypically normal because she has one copy she has one copy of the normal dominant gene. So that one will be an h.
The normal dominant gene that will be a hemophilia recessive gene in this case unless suppose she marries a normal man now hell have an x big h. Because its normal. This is what ive got ive only got one gene for producing factor.
8. But thankfully. I dont have hemophilia because one gene is more than enough but on the y chromosome.
There is no homologous position. So the y chromosome is a zero is not carrying anything so as we would expect we produce gametes and they would be the range of gametes that we could have now this one could combine with that one giving us a girl with two big anxious so shes gene of typically homozygous phenotypically normal. Because yes.
Two copies two copies of the normal dominant gene. Which is good and the other advantage of this is she cant pass this on to the next generation because she doesnt have the abnormal hemophilia gene. Another possibility is that x h.
There combines with that y zero and there we have a boy who does not suffer from hemophilia.
Because its got one copy of the normal dominant gene. This is what most men are in fact. Which is which is good another possibility is that one with that one now that gives us an x and an x.
So weve got a girl that ones a small h. And that ones a big age. Now this girl is not going to suffer from hemophilia.
Because she has one copy of the normal dominant gene. So phenotypically shell be fine. But of course she could potentially pass that defective hemophilia gene on to the next generation.
The fourth possibility is that looking up an x from there and a y from there so here. We have an x small h y. 0.
And unfortunately. This boy does not have a copy of the normal dominant gene therefore he cannot produce factor. 8.
Therefore he will suffer from haemophilia so very often in these sex linked genetic characteristics. Its the women that carry it but very often its the boys that suffer from it because they are no second opportunity to carry a copy of the gene on their small y chromosome. .
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