Name: 有糸分裂。分裂は複雑 - クラッシュコース生物学 #12 (Mitosis: Splitting Up is Complicated - Crash Course Biology #12)
Uploaded: 2021-01-14T04:21:16.000Z
Duration: 10 min 48 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

仮定法過去完了

I bet you wish you could do this have a clone clean up around the

apartment for you go to class, maybe take your Mom

Well, you can't do that. And actually there are some really

We're going to talk about those in the next episode.

But, do you know what CAN clone themselves?

Like, almost every single one of them. And in fact

For any creature bigger than a single-celled organism,

all of life stems from cells' ability to reproduce themselves,

to develop, grow, heal and keep from dying, for as long as possible.

This particular kind of cell division is called mitosis,

and it's responsible for a whole lot of your body's key functions.

If you get a cut, your body needs to make new cells. Mitosis.

Have too much to drink and damage your liver?

Tumor growing in your spine? Unfortunately, again mitosis.

While you go from a seven pound baby to a seventy pound child it's not

This process is so central to your life that it will take place

in your body, over your lifetime, about 10 quadrillion times.

Like all split ups, it's not easy. It's going to maybe be

a little bit messy, there's a lot of drama,

and it can take a surprisingly long amount of time.

But trust me, after we're done with it we'll all be better off.

So you are made of trillions of cells just like giraffes

And remember that inside each cell there's a nucleus that

stores your DNA, which contains all of the instructions

in your body cells, or somatic cells, you have 46 chromosomes

one in each pair is from your mom, and the other one's from your dad.

Cells with all 46 chromosomes are called diploid cells,

because they have 2 sets each. And that's what we're

You also have haploid cells that have half as many chromosomes (23).

And those are your sex cells. They're produced in an equally

fantastic process called meiosis, which we'll be talking about

But for now, the main thing to remember about mitosis is that

it allows one cell with 46 chromosomes to split into

two cells that are genetically identical,

each with 46 chromosomes. All in order to keep the

Now, the nucleus in your cell controls everything that

It has all of the instructions necessary for making

the cell survive so you don't need to duplicate the whole cell.

All you need to do is duplicate the DNA, get it wrapped up,

and then if you have two separate pockets of DNA, that's all you need

Mitosis takes place in a series of discrete stages called

prophase, metaphase, anaphase, and telophase.

And you can just say that over and over again,

And part of what's really amazing about this whole process is that,

while we know what these stages are, we don't always know the underlying

And this is part of science. Science isn't all the stuff we know,

it's how we're trying to figure all this stuff out.

Consider it job security if you want to be a biologist;

there is a lot of stuff that future biologists have to still figure out,

So, most of their lives, cells hang out in this

limbo period called interphase, which means they're in between

episodes of mitosis, mostly growing and working and doing all the stuff

that makes them useful to us. During interphase, the long strings

of DNA are loosely coiled and messy, like that dust bunny of dog fur

But as the mitosis process begins to gear up,

lots of things start happening in the cell

to get ready for the big division. One of the more important things

set of protein cylinders next to the nucleus, called the centrosome, duplicates itself.

We're going to have to move a lot of stuff around in the nucleus

and that's going to be regulated by these centrosomes.

The other thing that happens is all of the DNA begins

giving the cell two copies of every strand of DNA.

To brush up on how DNA replicates itself like this,

check out this episode and then come on back.

Now the cell enters the first phase, or the prophase, when that mess of

chromatin condenses and coils up on itself

wrapped around proteins - those my friends, are your chromosomes.

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有糸分裂。分裂は複雑 - クラッシュコース生物学 #12 (Mitosis: Splitting Up is Complicated - Crash Course Biology #12)

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