12/27/2023 0 Comments X linked genes50 percent of the males are hemophiliacs. So 50 percent of the males are normal and this guy here however, he's a hemophiliac. So 100 percent of the females and I'll use the symbol for female are normal whereas this guy is normal. This daughter is normal even though she's a carrier, they both have normal blood clotting. And what you'll see with sex linked traits, the way to spot them is that you'll see an equal expression of the traits in male versus female. Daddy gives y that he has and that and now we have our two sons. So we'll see that the daughters are both normal. Remember you always put the dominant allele first. Little h from mummy and big h from daddy. x from mummy with a big h and daddy's daddy's y. So let me put this daughter here is xx and gets a big h here and a big h there from mummy and daddy. And now it's time for them to have some babies. So now that I've got their genoptypes figured out, let me plug in them in to this punnett square here. So that means she has one normal and one hemophilia allele. The woman, she is normal but she's a carrier. So he has the normal blood clotting allele. ![]() What does that mean? Well, that means that he does not have the hemophilia allele. So the first thing you have to do is figure out alright, a normal man. A normal man marries a woman who is a carrier for hemophilia. Now what would some of the problems that would involve sex linked traits look like? Here's a standard kind of question. So they can be homozygous dominant with x big h x big h or heterozygous x big h x little h, or homozygous recessive x little h x little h. Males sorry females will actually get two x chromosomes. ![]() Instead, some people will call that hemizygous because it has half the normal number of chromosomes and hemi means half. So you can't say they're homizygous or heterozygous or anything like that because they don't have two of the same or two different things. Now males again only get one x chromosome. You put the capital H for normal or the lower case version for hemophilia. Now because they're on the x chromosome, when you write them instead of putting just the letter big H for having normal blood clotting and little h for having hemophilia, you actually put the x to represent the x chromosome and typically as a super script floating up high like an exponent. ![]() Some common examples of tricks that are used during tests or in class that are sex linked are hemophilia and color blindness. Now that's a significant difference from the standard way of doing genetics which is talking about the autosome or chromosomes because unlike the autosomes, the other non-sex chromosomes, males only get one of those x chromosomes. Now sex linked genes are those genes that are found on the x chromosome. One of the most common complications to introduce to Mendel's laws is the idea of sex linked traits.
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