by Jason Amores Sumpter
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in this video, we're going to introduce non disjunction and so non disjunction is an error that can occur during either my Asus one or My Asus two. When chromosomes fail, two separate from each other, which can result in an you employed cells now and you employed cells. Our cells that are going to contain either too many or too few chromosomes and again and employed cells can be the result of a non disjunction. Now non destructions resulting in an employed cells can lead to genetic disorders for example, trisomy 21 or down syndrome or it could even lead to cell death. And so let's take a look at our image down below, which is showing you non disjunction during an A phase one of my oasis one or, uh, in phase two of my Asus two. And so notice here at the top, we're showing you a cell undergoing my oh sis one. And here at the bottom, we're showing you a cell undergoing my oasis to and again. Non disjunction can occur either during my hostess one or my oasis to when thes chromosomes are going to fail to separate properly. And so here what you can see is during meta phase one of my Asus one. The homologous chromosomes are going to, uh, randomly and, uh, independently align themselves in two rows on the meta phase plate. And so what you'll see here is in this image, we're showing you the non disjunction of a small blue chromosome. And so this small blue chromosome, if anna phase were to occur properly, it should shift over to this side of the cell. However, if a non disjunction occurs of the small blue chromosome, notice that the small blue chromosome is actually going to go to the same side as its homologous chromosome pair. And so this side over here is going to be missing the homologous chromosome, whereas this side over here is going to have an additional homologous chromosome. And so what you'll notice is that this cell here, which would represent the cell here at the top, is going to have to many chromosomes. And so if you have too many chromosomes, that is going to be a type of annual ploy, I'd so on DSO notice that this cell over here on Lee has one replicated chromosome, so it has too few chromosomes. And so you could see something similar occurring with my Asus two down below on again in my oasis to the chromosomes all line up in one single file wrote. And this time you could see that there's non disjunction of the large red sister chromatic IDs. And so, usually, during my Asus two, this sister Crowe matted would go, uh, to the bottom and the other sister chromatic, would go to the top. But if there is non disjunction, then notice that this bottom, the sister chromatic here, is not going to separate. It's going to fail to separate, and so notice that both sister Chromatic would end up over in the same cell and this cell would be lacking. Ah, sister chrome, it'd. And so again you would end up getting a cell that has too many chromosomes and a cell that has too few chromosomes. And so again, if a cell has either too many or too few chromosomes, they're referred to as an employed cells. And again, um, this non disjunction can lead to genetic disorders such as again Trisomy 21 or Down syndrome and trisomy 21 askew can see here try as a route that means three. And Trisomy 21 is referring to having three copies of chromosome 21. And so, if we take a look at this, carry a type that we have over here on the right, notice that there are two pairs of every single chromosome except for this pair right here. And this pair noticed that there are actually three copies of this chromosome chromosome 21 that leads to the genetic disorder trisomy 21 which is Down syndrome. And so we're showing you a baby here, a cute baby with down syndrome and so which you'll notice here is that we have finished our lesson here introducing non disjunction and how non disjunction is an error that can occur during my oasis, where chromosomes or sister chromatic has failed to separate, resulting in an applied cells with either too many or too few chromosomes. And so 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