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Main content
Current time:0:00Total duration:5:51

Comparing mitosis and meiosis

AP.BIO:
IST‑1 (EU)
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IST‑1.F (LO)
,
IST‑1.F.1 (EK)
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IST‑1.G (LO)
,
IST‑1.G.1 (EK)
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IST‑1.H (LO)
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IST‑1.H.1 (EK)
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IST‑1.H.2 (EK)
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IST‑1.H.3 (EK)

Video transcript

before we go in-depth on meiosis I want to do a very high level overview comparing mitosis to meiosis so in mitosis and this is all a review if you've watched the mitosis video in mitosis we start with a cell we start with a cell that has a diploid number of chromosomes I'll just write 2n to show it has the diploid number for human beings this would be 46 chromosomes 46 for for 46 for humans you get 23 chromosomes from your mother 23 chromosomes from your father or you could say you have 23 homologous pairs which leads to 46 chromosomes now after the process of mitosis happens and you have your cytokinesis and all the rest you end up with two cells that each have the same genetic information is the original so you now have two cells that each have the diploid number of chromosomes so 2n + 2 n and now each of these cells are just like this cell was it can go through it can go through interphase again and it grows and it can it can it can replicate its DNA and it's centrosomes and grow some more and then each of these can go through mitosis again and this is actually how you're most of the cells in your body grow this is how you turn from a single cell organism into you or for the most part into you so that is mitosis and one way to think when it's a cycle after each of these things go through mitosis they can then go through they can then go through the entire cell cycle again and let me write this a little bit neater mitosis that s was a little bit hard to read now what happens in meiosis and what happens in meiosis I'll do that over here and meiosis something slightly different happens and it happens in two phases so you will start with a you still start with a with a cell that has a diploid number of chromosomes so you will start with a cell that has a diploid number of chromosomes and in its interphase it also replicates its DNA and then it goes through something called meiosis one and in meiosis one what you end up with this two cells that now have a haploid number of chromosomes so you end up with two cells you now have two cells that each have a haploid number of chromosomes so you have N and you have n so if we're talking about human beings you have 46 chromosomes here and now you have 23 chromosomes and this in this nucleus and now you have 23 in this nucleus but you're still not done then each of these will then go through a phase which which I'll talk about in a second which is very similar to mitosis which will which will duplicate this entire cell into two so actually let me do it like this so now this one you're going to have four you're going to have four cells that each have the haploid number that each have the haploid number of chromosomes and they all don't necessarily have the same genetic information anymore because as we go through this first phase right over here of meiosis and this first phase where you go from diploid to haploid right over here this is called meiosis 1 meiosis 1 you're essentially splitting the homologous pairs and and so this one might get some of the homologous some of the some of the ones that you originally got from your father and some of the ones that you originally got from your mother some of the ones you originally got from your father some of the ones that you originally got from your mother they split randomly but each homologous pairs each homologous pair gets split up and then in this phase meiosis 2 so this phase right over here is called meiosis 2 it's very similar to mitosis except you're now dealing with cells that start off with the haploid number it's important realize meiosis is not a cycle these cells that you have over here these are gametes these are sex cells these are gametes these can now be used in fertilization if we're talking about if you're male this is happening in your testes and these are going to be sperm cells if the if you are female this is happening in your ovary and these are going to be egg cells if you are a tree this could be pollen or it could be an ovule so these are but these are used for fertilization these will fuse together in sexual reproduction to to get to a fertilized egg so that which then can undergo mitosis to create an entirely new organism so not a cycle here although I guess wants you know these these will find sex cells from another organism and and and fuse with them and then those can turn into another organism and I guess the whole circle of life starts again but it's not the case with mitosis where this could just keep on going and going going the this cell is just like this cell while these sex cells are different than this one right over here now where does this happen in the body and we've talked about this in previous videos these are these are the bulk of these are your somatic cells right over here these are the ones that make up the bulk of your body somatic cells and where is this happening well this is happening in germ cells as we mentioned if you're male it's in your testes and if you're female it's in your ovaries and germ cells actually can undergo mitosis to produce other germ cells that have a diploid number of chromosomes or they can undergo meiosis in order to produce sperm or egg cells in order to produce gametes
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