It now has four chromosomes.

They're being pulled apart, but they're being pulled apart the homologous pair is being pulled apart, not the actual chromosomes, not the chromatids.

And just like in mitosis, as soon as the sister chromatids are split apart, they are now referred to as chromosomes, or sister chromosomes.

So it's analogous to anaphase in mitosis, but the key difference is you're pulling apart homologous pairs.

You have your two chomosomes, each made with sister chromatids, each made with two sister chromatids.

And then the second phase separated the sister chromatids, just like what happens in mitosis.

Even though we have two chromatids, one for each chromosome, now we have four chromatids, two for each chromosome, we still say we only have two chromosomes.

In a human's case, you would have 46 of them.

Sometimes this is called a tetrad because it has four chromatids in it, but it's in a pair of homologous chromosomes.

So I have one chromosome from my dad, and it's made up of two chromatids, so it's already replicated, but we only consider it one chromosome, and then I have one from my mom in green.

We started up here with a diploid germ cell, and we went through two stages of division.

One from my mom in green, and it also has two chromatids.

So I had that one chromosome there, and then I have another one here.

It's not like one is getting two versions of a gene and the other is getting two versions of another gene.

And you could already see, this process right here, you essentially split up your chromosomes, because you end up with half in each one, but here, you start with N and you end up with two chromosomes that each have N, so it's very similar to this.

So you have the longer purple one.

When we talk about meiosis, we have to be careful to show the homologous pairs.

Anaphase I, the homologous pairs were broken up, but the chromosomes themselves were not.

Now, in anaphase Il, we don't have homologous pairs.

And I'm just drawing the nucleus here.

It didn't have that crossover occur.

And then let's say that last one actually helps to determine my gender, or it fully determines my gender.

It's fuckedup chromosomes.

Remember, in interface, even though I drew it this way, they don't exist in this state, the actual chromosomes.

But one thing that is universal for all sexually reproducing organisms is that gametes have half the number of chromosomes as the zygote, or you can kind of view it as the organism itself, the way we conventionally think about it.

He gets split up into two chromatids, which we are now calling chromosomes, or sister chromosomes.

Let me do it in blue.

Let me just cut and paste what I have. I have this one, this chromosome right here.

Chimpanzees have two sets of 24, or 24 pairs of chromosomes.

Rhesus monkeys have 21 pairs of chromosomes.

So prophase in I, you also have this happening.

Now we're in metaphase, and metaphase really is just an aligning of the chromosomes, so all of the chromosomes are going to be aligned at the center of the cell.

So when we enter anaphase I, you have just the homologous pairs separate, so the chromatids stay with their sister chromatids.

There's just a gazillion of them that are all duplicates of the cell, and they all contain the 2N number of chromosomes, the diploid number of chromosomes.

We get one from mom, one from dad.

So let me say it has this chromosome right here and then

But we're going to focus on the region labeled red here and it's the interface between the dynamic scaffolding and the chromosomes.

Let me see, it'll look like this.

Once again, we're not even in mitosis yet.

It's just growing, accumulating materials and building itself out, and then it actually replicates its chromosomes.

Centrioles are these little structures, these little can shaped structures inside the centrosomes, and the centromere are the center points where the two chromatids attached to each other within a chromosome.

And the first chromosome we built in 2008 the 500,000 base pair one we simply assigned the names of the authors of the chromosome into the genetic code, but it was using just amino acid single letter translations, which leaves out certain letters of the alphabet.

Now, each of those copies are called chromatids, and that magenta one will do the same thing.

The centromeres are these things connecting these sister chromatids.

I got from my dad.