 Okay, it's a super sad story and I feel like this is awful. I'm still here, but you can't see me anymore because I have to show you my socks. There they are. This is my pile of socks. Now, I've made little signs of all the stages in meiosis so that you can keep track of where we are in this process and we're gonna begin in interface. So I'm actually gonna move my signs out of the way. Look at me, move them. I hope those don't get lost in the chaos. And you tell me, think through what is going on in interface. Interface, our DNA is in chromatin form. This is not really accurate to chromatin form. If you look at all of my socks, you'll notice that they're definitely not chromatin. They're more log-like than tangle-like. And if you imagine that I like unwound each sock, you totally have an awesome analogy for what chromatin would look like. But look at the socks that I have gathered together. You'll notice that I have only one of each kind of sock and I probably could have done this with fewer socks but I really wanna show you this whole process. If you, just looking at my socks, I've sort of already got them grouped together. If you were, oh, here's somebody else that's coming into the mix. If you were to look at these socks and try to figure out their homologs, like what socks are possibly representing homologous pairs? Dude, how cute are those little baby booties? Do you agree that these two baby booties, they're not a match. A match would represent your sister chromatids because a match would be identical. Look, oh, here's some more socks. Look, here's a match for my baby booty. That mean that right there, those would be sisters. But these guys, do you agree they're really similar? So those are a nice homologous pair. I know that I got these two pairs of socks at the same time, they're like the same kind of sock even though their colors are super different. So I matched them up as, and I'm saying these guys are homologs. I'm also calling my black socks homologs. I have some pink socks here. I'm calling these guys homologs. I've got some white athletic type socks. Those guys are gonna be homologs. Can you see how they're not the same sock? But they're pretty similar, it works to call them homologs. And then I've got this random blue athletic sock and this really long, fleecy like slipper sock thing. And I'm actually gonna match those guys up as a homolog. And just push pause really fast and tell me like, dude, why? What could those possibly be? They don't look anything like, they're literally like nothing alike. I'm saying this as a boy critter with an X chromosome and a Y chromosome. And there's just enough similar DNA on the X chromosome and the Y chromosome that they're able to hook up when homologs hook up. And they're actually, they are considered to be homologous chromosomes. Okay, so right now, if we were to look at this whole thing, oh yeah, look at that. We're in G one of interphase. What's the next stage of interphase that happens? You know, as true doggies, we know that S is gonna happen. What happens in S? Well, it's pretty straightforward. We're gonna double our DNA. DNA replication is gonna happen. This is where we get sisters. This is where I say, okay, here I actually am gonna make an identical copy of my chromosome. It's a sister chromatid. That means it's attached at the centromere. And I can actually attach them. I'm gonna go away. I'm gonna do have to do some editing to put this thing together. I'm gonna go away and I'm gonna create, I'm gonna let S happen. Takes eight hours in a human cell. You know, I can do that. And then I'm gonna come back after S has occurred. Look, it's a miracle. I folded my laundry. Anyone in my family would know that is definitely a miracle. Okay, so I have, you can't really see it super well, but I have sisters. Every single sock has a pair. I actually attached them. I'm like imagining that's like the centromere. The sisters are attached at the centromere. Because this whole thing is attached, the two sisters are attached at the centromere, this is considered one chromosome. So I started out with two copies of every homologue and that hasn't changed. I still have two copies of every chromosome, even though I doubled my DNA. So at the end of S, we now have twice as much DNA and our copies of our DNA are attached at the centromere. And that's where I have my sister chromatids. Now we're gonna go into G2, which basically nothing happens. I mean, there's a ton of stuff that happens, but who cares? We don't. Now we're gonna move into Prophase 1. During Prophase 1, you imagine that all my socks were yarn. They're no longer yarn, no, no, no. They are now wound up into nice little socky bundles, still attached to their sister chromatids at the centromeres. Now for illustrative purposes, I've already shown my homologs together, but remember that the homologs actually hook up. They connect with each other during Prophase 1 and they actually start swapping parts. I can't show you because I have to have one hand doing this filming, but I could switch sock parts. Like this thing could come off and this thing could come off and I could switch and illustrate crossing over. If you were super dedicated, you would start chopping up your socks for this activity. Okay, so now our chromosomes are all compacted. Our homologs have hooked up. We've crossed over. Now we're gonna move into Metaphase 2. I mean Metaphase 1, because we haven't even gone through meiosis. Holy crud yet. Okay, what happens during Metaphase 1? My homologs line up on the Metaphase plate. So look what I am going to do. I'm lining up my homologs and do you think I need to clean my office? Be quiet, don't tell me that. Okay, there's the Metaphase plate and homologs are lined up together on that Metaphase plate. Do you see this? Take a deep breath, everybody stop. This is where independent assortment happens. Do you agree that the next step in Anaphase 1, what we're going to have happen is we're actually going to separate homologs. They separate to different poles of the cell. Do you agree with that? My homologs are separating. Can you visualize this little activity? You should definitely do this at home. There's one cell. Here's another cell. After we go through Anaphase and we go through telophase, now come back with me to the idea of independent assortment. Do you agree that the process of meiosis 2? We're just going to do that thing again except do we have homologs to hook up with? All right, I got cut off, but I don't know why. Okay, so we don't have homologs to hook up with. So instead we are going to, our sisters are going to split in meiosis 2. And that just means, now look at this, do you agree that the cells that result from meiosis 2, those two cells, those two daughters that are going to come from that line of chromosomes are going to be identical, right? Each one of those daughters is going to get that stripy guy and that red guy and that pink guy and they're going to get one copy of each. Does that work for you? If during metaphase one, okay look, this is the point at which independent assortment occurs. If during metaphase one, instead of lining up like this on the metaphase plate, they lined up like that, do you agree that my outcome is actually a different cell? I'm going to have a different genetics. So watch, if, here's where it matters. If there's an eye color gene here and a hair color gene here, in this case, if we've got a blue eye allele and a purple eye allele and blue hair and purple hair, if we line up this way, this gamete is going to get, oh dear, purple eyes and purple hair. This gamete is going to get blue eyes and blue hair. Do you follow that? But if I switch these, the gamete is going to get, oh crap, would I say blue eyes and purple hair and blue hair and purple eyes. Did you follow that? Because each of my line of, what are those socks? Each of my sock lines represents a gamete, an actual gamete that can be combined to make babies. Now I'm going to go away one more time and then I'm going to come back and show you my end game cells. It makes perfect sense to me. So if it doesn't make sense to you, I just don't know. Look at my socks. First of all, let's just make a commentary on the fact that dude, I think I need a little bit of a bigger office space. Yes? Just a little bit. Okay, but if I had bigger office space, you might be able to see this a little more clearly that here are the chromosomes that make up one cell. Those are the chromosomes that make up another cell. Here's another cell and here's another cell, okay? If I lined them up differently on the metaphase plate, I would get different gametes at the end. Here are my four gametes. All I have to do is a little mix and then match it. If I had done this instead, lined them up like this and crossed them like that, I would end up with a different kind of gamete. And if you remember from your lab, it's like eight million different possible gametes that we can get just from lining up our 23 pairs of homologs in metaphase one in different arrangements. Eight million, like that's insane. That's an incredibly huge number of gametes and that doesn't account for crossing over. So hopefully, like after this, hopefully you sit down, sit down, and work your way through, like do it. Get some socks and actually do it, lay them out there or use your model that you made in the lab and find your homologs. Remember homologs have similar characteristics. They have the same genes on them, but they're not the same chromosome, same genes. They look really similar, but they're a little bit different. They have different alleles on them. One came from mom, one came from dad. So you have some genetic diversity between your homologs, but do you have any genetic diversity in your sisters? No, sisters are identical. Sisters result from synthesis in interface, in the S phase. Okay, I hope this didn't make it worse. Now I have to go edit this thing. Peace.