You have isolated two petite mutants, pet1 and pet2, in ...

Question

You have isolated two petite mutants, pet1 and pet2, in Saccharomyces cerevisiae. When pet1 is mated with wild-type yeast, the haploid products following meiosis segregate 2:2 (wild type : petite). In contrast, when pet2 is mated with wild type, all haploid products following meiosis are wild type. To what class of petite mutations does each of these petite mutants belong? What types of progeny do you expect from a pet1 × pet2 mating?

Accepted Answer

Hi, everybody. Here's our next question which the following does not follow Mendel's law of independent assortment. Well, let's recall what Mendel's law of independent assortment says from our content videos. So it says that alleles of two or more different genes get sorted into gametes independently of each other. And Mendel didn't know. But of course, we know that this is due to the random assortment of the parental chromosomes. So there's two sets of chromosomes are lined up in the middle of the cell during mitosis and they randomly. So you don't get maternal on one side and paternal on the other there mixed up and randomly go to one or the other daughter cell. So we need to see which the answer choices doesn't follow that law of independent assortment. So let's look at choice. A and let's note also that when we look down through our answer choices, if we glance over them briefly, which is always a good idea, we see that choice D is all options are correct. So we do have the option of more than one of these, all of them being examples of this. So choice A says closely linked genes Well, these are not going to follow Mendel's law of independent assortment because if our genes are very close together on the same chromosome, so close together on the same chromosome, they will be most likely inherited together. Um Mendel got lucky with the traits. He studied that they were on different chromosomes. So they did independently assort had he picked something where the two genes were close together on the same chromosome. It would have been a little more confusing. So closely linked genes do not follow this law since they're close together on the same chromosome. If they're far apart, they may almost come close to following this. Since do we have recombination that that can occur when they're farther apart? But the closely linked genes will not do that choice. B says X linked genes. Well, these are not going to follow Mendel's law of independent assortment because males and females don't have the same number of X chromosomes. So when you have, for instance, the male parent and you have this X and Y gametes, only one daughter cell will get an X chromosome. So a trait on the X chromosome will only go to one or the other daughter cell. Um The matching daughter cell will not have that gene because of having a Y chromosome instead of an X. So choice B is also correct. Well, if I were on a test and in a hurry, I'd go ahead and pick choice D all options are correct since I've got more than one correct answer, but to be thorough, will look down at choice, see sex linked genes. So that would mean they could be on either the X or the Y chromosome. But again, that's not going to be independent assortment for the same reason as the excellent genes, a gene on the Y chromosome. Again, there's only one Y chromosome so that Y chromosome will go to either one or the other of the daughter cells and the other daughter cell won't have it at all. So choice C is also correct and our answer choice is choice d all options are correct for which of the following does not follow Mendel's law of independent assortment. See you in the next video.

My Courses

Chemistry

Biology

Math

Physics

Business

Social Sciences

Programming

Product & Marketing