Name: 染色體、染色體、染色質等。 (Chromosomes, Chromatids, Chromatin, etc.)
Uploaded: 2021-01-14T04:59:09.000Z
Duration: 18 min 23 s
Description: 【看影片學英語】數萬部 YouTube 影片，搭配英漢字典即點即查，輕鬆掌握單字發音與用法，長久累積看電影不必再看字幕。

Before I dive into the mechanics of how cells divide

I think it could be useful to talk a little bit about

關係子句

a lot of the vocabulary that surrounds DNA

There's a lot of words and some of them kind of sound like each other

So the first few I'd like to talk about is just about how

DNA either generates more DNA,makes copies of itself

and we've talked about this in the DNA video

I'm just going to draw a small section of DNA

I have an A, a G,a T,let's say I have two T's and then I have two C's

So A corresponds to T, G with C, it forms hydrogen bonds

with C, T with A, T with A, C with G, C with G

And then, of course, it just keeps going on in that direction

So there's a couple of different processes that this DNA has to do

One is when you're just dealing with your body cells

and you need to make more versions of your skin cells

your DNA has to copy itself, and this process is called replication

And this is one of the beautiful things about how DNA is structured

but the idea is these two strands separate

It's facilitated by a bunch of proteins and enzymes

but I'll talk about the details of the microbiology in a future video

and then once they've separated from each other,what could happen?

Let me delete some of that stuff over here

Now once they separate, what can each of these do?

They can now become the template for each other

If this guy is sitting by himself, now all of a sudden

a thymine base might come and join right here

so these nucleotides will start lining up

So you'll have a thymine and a cytosine, and then an adenine

adenine, guanine, guanine, and it'll keep happening

this other green strand that was formerly attached to this blue strand

You have an adenine, a guanine, thymine, thymine, cytosine, cytosine

By separating and then just attracting their complementary bases

We'll do the microbiology of it in the future

This is how the DNA makes copies of itself

And especially when we talk about mitosis and meiosis

I might say, oh, this is the stage where the replication has occurred

Now, the other thing that you'll hear a lot

and I talked about this in the DNA video, is transcription

In the DNA video, I didn't focus much on how does DNA duplicate itself

but one of the beautiful things about this double helix design is it

You just split the two strips, the two helices

and then they essentially become a template for the other one

Now, transcription is what needs to occur for this DNA

but transcription is the intermediate step

It's the step where you go from DNA to mRNA

And then that mRNA leaves the nucleus of the cell

and goes out to the ribosomes, and I'll talk about that in a second

So this guy, once again during transcription

So that was one split there and then the other split is right there

And actually, maybe it makes more sense just to do one-half of it

Let's say that we're just going to transcribe

Let me erase all this stuff right-- nope, wrong color

Now, what happens is instead of having deoxyribonucleic

acid nucleotides pair up with this DNA strand

you have ribonucleic acid, or RNA pair up with this

And so thymine on the DNA side will pair up with adenine

Guanine, now, when we talk about RNA, instead of thymine

we have uracil, uracil, cytosine, cytosine, and it just keeps going

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染色體、染色體、染色質等。 (Chromosomes, Chromatids, Chromatin, etc.)

essentially

wrap

structure

separate