Name: 遺伝学入門 (Introduction to Heredity)
Uploaded: 2021-01-14T08:35:09.000Z
Duration: 17 min 27 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：

程度の副詞

Well, before we even knew what DNA was, much less how it was

基礎受動態

structured or it was replicated or even before we

could look in and see meiosis happening in cells, we had the

general sense that offspring were the products of some

That if I had a guy with blue eyes-- let me say this is the

blue-eyed guy right here --and then if he were to marry a

brown-eyed girl-- Let's say this is the brown-eyed girl.

Maybe make it a little bit more like a girl.

If he were to marry the brown-eyed girl there, that

most of the time, or maybe in all cases where we're dealing

with the brown-eyed girl, maybe their kids are

Let me do this so they have a little brown-eyed baby here.

And this is just something-- I mean, there's obviously

thousands of generations of human beings, and we've

We've observed that kids look like their parents, that they

inherit some traits, and that some traits seem to dominate

One example of that tends to be a darker pigmentation in

Even if the other parent has light pigmentation, the darker

one seems to dominate, or sometimes, it actually ends up

being a mix, and we've seen that all around us.

Now, this study of what gets passed on and how it gets

passed on, it's much older than the study of DNA, which

was really kind of discovered or became a big deal in the

And kind of the father of classical genetics and

He was actually a monk, and he would mess around with plants

and cross them and see which traits got passed and which

traits didn't get passed and tried to get an understanding

of how traits are passed from one generation to another.

So when we do this, when we study this classical genetics,

I'm going to make a bunch of simplifying assumptions

because we know that most of these don't hold for most of

our genes, but it'll give us a little bit of sense of how to

predict what might happen in future generations.

So the first simplifying assumption I'll make is that

some traits have kind of this all or nothing property.

Let's say that there are in the world-- and this is a

gross oversimplification --let's say for eye color,

An allele is a specific version of a gene.

So let's say that you could have blue eye color or you

That we live in a universe where someone could only have

one of these two versions of the eye color gene.

We know that eye color is far more complex than that, so

Let me say that, I don't know, maybe for tooth size, that's a

trait you won't see in any traditional biology textbook,

and let's say that there's one trait for big teeth and

And I want to make very clear this distinction between a

I talked about Gregor Mendel, and he was doing this in the

1850s well before we knew what DNA was or what even

chromosomes were and how DNA was passed on, et cetera, but

let's go into the microbiology of it to understand the

Let's say on some chromosome-- let me pick

And on this chromosome, there's some location here--

we could call that the locus on this chromosome where the

eye color gene is --that's the location of

Now, I have two chromosomes, one from my father and one

from my mother, so let's say that this is the chromosome

We know that when they're normally in the cell, they

aren't nice and neatly organized like this in the

chromosome, but this is just to kind of show you the idea.

Let's say these are homologous chromosomes so they code for

So on this gene from my mother on that same location or

Now, I might have the same version of the gene and I'm

Now, if I have the same version of the gene-- I'm

going to make a little shorthand notation.

I'm going to write big B-- Actually, let me do

I'm going to write little b for blue and I'm going to

There's a situation where this could be a little b and this

And then I could write that my genotype-- I have the allele,

I have one big B from my mom and I have one