So speaking of babies, when it
comes to reproductive cell division,
we're going to do
things a little differently.
And the reason why is because we actually
want a different result than that of mitosis.
So in reproductive cell
division, our reproductive cells
or the sperm cells in male
or the oocytes cells in females
are going to undergo a division so they
end up with half the number of chromosomes
than what they started with.
So what do I mean by that?
Remember in all of your cells, you
have two sets of 23 chromosomes
for a total of 46 chromosomes.
So let's think about it in terms of shoes.
So you have a right shoe and a
left shoe, but they are a pair of shoes.
That's how your chromosomes are.
You have one chromosome from your
mom and one chromosome from your dad
and together, they make
a set of chromosomes.
So remember in S phase, we
duplicated all of our chromosomes
so now, they are held together in an x-like form
and we we refer to them as sister chromatids.
In the first part of meiosis or meiosis I,
what I'm going to do is separate the two shoes
so I'm going to put the left shoe in one
cell and the right shoe in another cell.
They're still duplicated or in the 'sister
chromatid form' but they are now in separate cells.
This is referred to as
going from diploid to haploid.
Now in meiosis II, my haploid cells still
contain the sister chromatids or the Xs
where the two duplicated
chromosomes are now in the same cell,
and I need to separate those
two duplicated chromosome
and to individual chromosomes in each cell.
So at the end of meiosis II, you started with
one cell and you end up with four separate cells
each with half the number of
chromosomes that you started with.
And now for reproduction to occur,
we allow one cell to fuse with another
and now we have two sets again.p