Prophase 1 diagram8/20/2023 So then it had a little bit of pink on it. The shorter orange chromosome on this cell had the longer, the Let me, has a littleīit of the orange here, and then I had the And this had a little bit of orange in it. And actually, let me drawĪll the magenta ones now since I have my magenta color selected. So this magenta one, it'll line up here over here. And I have my now dense chromosomes lining up along the equator here. And I'm gonna do it twice, because I'm now dealing with two different cells. So our centrosomes have migrated to the poles. And actually all of meiosis II is very similar to what And you can just imagine, it's very similar to what Let me draw an arrow here so you can see that we are entering into another phase. So once again, very strong analogy, especially to frankly, So the centrosomes have replicated and they will start to migrate to opposite ends of the cell. Shorter orange chromosome just like that, so they have condensed, and you've actually, each of these cells now will have duplicate centrosomes. ![]() You have this chromosome, right over here, and it had a little orange section from the chromosomalĬrossover just like this, and then you have the Little bit of the magenta that was from the chromosomal crossover back in prophase I, and then you have thisĬharacter right over here that is shorter. Into their denser form, so it's gonna look like this, this, and this. So your nuclear envelope dissolves again, and your chromosomes once again condensing (mumbles) I guess you could say Your nuclear envelope dissolves again, so let me show a dissolving In prophase II, just like in prophase I, and just like in prophase in mitosis, and let me write the phases here, this is prophase II we're talking about, prophase II. So this is one of the cells right over here, and then this is the other cell right over here. To draw it properly, so let me draw it, so let me draw this one first. And in prophase II, now I'm dealing with two cells here, so in prophase II, and I'm gonna do it for both of the cells that I have after I finished meiosis I, so in prophase II, so let me. So you can imagine meiosis II starts with prophase II. But then we get into meiosis II, which will allow us toĬomplete all of meiosis. interphase II, which you could kind of view as a rest period. There can be a rest period where you have an interphase II, and that will depend on the type of cell and the species and all of that, but it is possible, so I'll actually put that over here. Went back into our interphase, "is there kind of a rest period "between our two phases of meiosis?" And the answer is, sometimes. And you might be wondering, "Well, hey, after mitosis, we Homologous chromosomes can exchange parts in a process called "crossing over.We had completed meiosis I, and now we're ready to go into meiosis II. In Metaphase I, homologous chromosome pairs line up. This shuffling process is known as recombination or "crossing over" and occurs while the chromome pairs are lined up in Metaphase I. Each sibling is 50% mom and 50% dad, but which 50% of each can vary in the siblings. But this happens independently for each trait, so just because you got your dad's brown eyes doesn't mean you'll get his blond hair too. Each sperm and egg will end up with either B or b from mom and either B or b from dad. This leads to four possibilities: You could get B from mom and B from dad, or B from mom and b from dad, or b from mom and B from dad, or b from mom and b from dad. Imagine, for example, that eye color was controlled by a single gene, and that mom could have B, the allele for brown eyes or b, the allele for blue eyes, and dad could also have B or b. But each non-identical-twin child of these parents ends up with a different combination. ![]() You ended up with half of mom's paired genes and half of dad's paired genes. ![]() Your parents each have at least one pair of alleles (versions of a gene) for every trait (and many pairs of alleles for each polygenic trait).
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