In this chapter, we focused on linkage, chromosomal mapping, and ...

Question

In this chapter, we focused on linkage, chromosomal mapping, and many associated phenomena. In the process, we found many opportunities to consider the methods and reasoning by which much of this information was acquired. From the explanations given in the chapter, what answers would you propose to the following fundamental questions?

How do we know that sister chromatids undergo recombination during mitosis?

Accepted Answer

Hi everyone. Let's look at our next problem. It says recombination between blank chroma tides. During mitosis only occurs around 1% as frequently as it does between blank chroma tides during blank. When we think about recombination, we're usually thinking about the process of mitosis and we're thinking about recombination between homologous chromosomes. And that's a really important part of the mitosis because that's one of the main benefits of sexual reproduction. Which may aosis is that key part of the process. Since recombination allows that greater genetic diversity, that's the main benefit of sexual reproduction. So we know that this is kind of our main realm of recombination is the non sister chroma tides. From two homologous chromosomes have crossover and exchange. However, there can be some recombination between the sister chroma tides that are being separated during mitosis. As we know in mitosis, those chromosomes line up along the middle of the cell during meta phase and the sister chromosomes are pulled apart. Um There can be some exchange of material between the sister chroma tides that seems to be a mechanism of DNA repair. Um But this is mostly suppressed in favor of the exchange between homologous non sister chroma kids. So when we look at our answer choices, we know that the less frequent event during mitosis will be recombination between sister chroma kids. So we want to look for an answer choice that has sister first. So we're going to see that's in choice B. And choice D. So we can go ahead and eliminate choices A and C. And we're saying that recombination between these sister chromosomes. During mitosis, old knickers about 1% as frequently as it does between and this is between the homologous chromosomes, which is the non sister chroma tides of those chromosomes. So we want non sister to be our next blank here. So we find that in Choice B. And Choice D. So that doesn't distinguish between it and that recombination event takes place during mitosis is the process. So that's going to lead us to Choice D. Which has me aosis here versus Choice B, which has mitosis as the last blank. So we're gonna eliminate Choice B. And we know that choice D. Must be our answer here. So again, recombination between choice D. Sister chroma tides during mitosis only occurs around 1% as frequently as it does between non sister chromosomes during mitosis. See you in the next video

Key Concepts

Sister Chromatids

Recombination

Chromosomal Mapping

Watch next