Independent Assortment

by Jason Amores Sumpter
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So now that we've covered crossing over in our last lesson video the first main event that creates genetic diversity during my oh, sis, In this video, we're going to talk about the second main event that creates genetic diversity during my oh sis and that is independent assortment. And so independent assortment occurs specifically during meta phase one of my oh sis one. And of course, during meta phase, we know that the chromosomes air going to align themselves in the middle of the cell and specifically during meta Phase one of my Asus one, the chromosomes are going to align themselves in homologous pairs in two rows on the meta phase plate. And so independent assortment refers to the ability of these pairs of homologous chromosomes to independently and randomly align themselves on the meta phase plate during meta phase one of my Oasis one. And so when these pairs of homologous chromosomes independently and randomly align themselves during meta phase one, this results in an enormous amount of possible genetic combinations during my oh sis and again independent assortment along with crossing over is part of the reason why my oh sis results in four Hap Lloyd cells that are all genetically different from one another. And so independent assortment helps to create mawr possible genetic combinations, making it ah very, very difficult to get to cells that are genetically identical during the process of my oh sis. And so it's actually possible to calculate the number of combinations due to independent assortment by using the equation to raised to the power of n where n here is the exponents and n represents the Hap Lloyd number of chromosomes in a cell. And so we'll be able to get some practice applying this equation here to calculate the number of combinations due to independent assortment when we get to our image down below. And so if we take a look at our image down below, notice that we're showing you, uh, two possibilities Possibility number one and possibility number two for independent assortment as it occurs during my oh, Sis and Soe, notice that possibility Number one is over here generating combination one in combination too. And possibility number two is over here generating combination three and combination for. And so notice that this first row right here represents Meta phase one of my Asus one and of course, during metaphysics is we know that the chromosomes are going to align themselves in the middle of the cell. But during meta phase, one of my Asus one homologous chromosomes are going to pair up, and they're going to align themselves in two rows on the meta phase plate. And so notice here in our representation were using a total four chromosomes and these air replicated chromosome that you can see here. That one possibility for these chromosomes to align themselves is that all of the maternal chromosomes inherited from the mother line up on one side, and all of the paternal chromosomes inherited from the father line up on the other side. So that's one possibility if the's homologous chromosomes are independently and randomly aligning during meta phase one. But if they're independently and randomly aligning on the meta phase plate here, it's also possible for uh, not for all the the mother's chromosomes to not be on one side. And so notice here on this image that they're not lined up on one side, and the father's chromosomes are also not lined up on one side. So this is another possibility for how these chromosomes can independently and randomly align and so notice that each of these possibilities here is going to result in a different genetic combination. And so over here, in this possibility, notice that both of the mothers homologous chromosomes are going to go to the left to create this cell here that has two of the, uh, mother's chromosomes and one cell. And these two from the father would both separate to the right to create a cell that has both of the father's chromosomes. But if they aligned with this possibility here, notice that one of the mothers is going to go to the left and one of the fathers is going to go to the left. And so you end up getting a cell that has one of the mothers and one of the fathers chromosomes. And the same goes for this other cell. Over here, one of the mothers fathers goes to the right and one of the mothers goes to the right as well. And you get this combination right here. And so these combinations are different. All of these combinations are here are different. And what you see here in this row, uh, this road right here eyes representing Meta phase two of my oasis to And of course, during meta phase two of my closest to the chromosomes are aligning in one single file line like they do in mitosis as well. And so you can see here the alignment of the chromosomes in one single file line. And so this is going to result in different genetic combination. So notice here you have this combination Number one is one possibility on. Then you have combination number two over here is another possibility. And then over here, if independent assortment occurred in this way, you'll get combination. Three in combination four, which are different than combinations one and two. And all of these represent different genetic combinations. And they all resulted from independent assortment how these chromosomes can independently and randomly align themselves during meta phase one of my Asus one. And so ultimately, what we're saying here is that independent assortment, this event that occurs during meta Phase one here the random alignment of these homologous pairs of chromosome It's gonna create a lot of possible genetic combinations. And this is just showing four combinations here, uh, using just four total chromosomes. But we know that in human cells there are actually 46 chromosomes, and with 46 chromosomes that would create ah lot mawr possibilities. And so you can again calculate the number of possible combinations by using this formula here to raise to the power of n where the variable n again represents the Hap Lloyd number of chromosomes. And so notice here in this example that we're showing you we would say that to to the end, if we were using this equation. The end here, the Half Floyd number of chromosomes and our cells is two chromosomes. Because the end result of my oasis we know creates hap Lloyd cells and the half Floyd number here in this example is to So we would take two. And the end here would be to and so to raise to the 22 squared essentially is two times two, which is four. And so the number of possible genetic combinations when there are the Hap Lloyd number is two is four genetic possible combination. And that's what we're showing you here. The four genetic possible combinations. Uh, that result, if you would only have four, uh, you know, total chromosomes and the deploy itself and to total chromosomes and happily itself. And so this year concludes our brief introduction to independent assortment how it occurs during meta Phase one and really, how it just consists of homologous chromosomes independently and randomly aligning to create an enormous amount of possible genetic combinations during my oh sis. And we'll be able to get some practice applying these concepts as we move forward in our course, So I'll see you all in our next video.