Name: Cancer | Cells | MCAT | Khan Academy
Uploaded: 2023-07-17T21:42:44.000Z
Duration: 12 min 36 s
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Most cells in the human body just go about their business

on a daily basis in a fairly respectable way.

This could be maybe a skin cell or really any cell in any

As that tissue is growing or it's replacing dead cells, the

cells will experience mitosis and replicate themselves, make

And then those two maybe will experience mitosis, and then

if they realize that, gee, you know, it's getting a little

There are other cells in my neighborhood.

They'll recognize that, and say, you know, I'm going to

And then let's say one of them experiences a little defect,

and he says, you know what, gee, something's a little bit

I, the cell, recognize this in myself, and the cells will

That's how good of cellular citizens they are.

They'll kind of make way for other healthy cells.

So this guy might even kill himself if he realizes that

There's actually a cellular mechanism that does that

This isn't some type of outside influence on the cell.

The cell itself recognizes that it's somehow damaged and

So that's the regular circumstance even when there

And just to give you an idea, even if mutations are

And I don't know the exact frequencies at

I suspect it's of different frequencies in different types

There are on the order of 100 billion new cells in the human

So even if a mutation only occurs one in a million times,

you're still dealing with roughly 100,000 mutations, and

maybe most of the mutations, maybe they're just some little

random things that don't really do a lot.

But if the mutations are a little bit more severe, the

cell will recognize it and destroy itself.

And I want to make a very clear point here.

I'm talking about the cells of the body or most of the body.

This could be the cells in my eye or the cells in my brain

So these mutations, even if the cell survives, will not be

That's an entirely different discussion when

These are all my body cells and they're replicating, and

So any mutations here, they'll either do nothing, or the

cells might malfunction a little bit, or the cells might

hurt themselves or hurt me, but they're not going to

And I want to make that point very clear.

Now, you're saying, hey, Sal, 100 billion new cells a day?

That must mean like every cell in my body has created, well

that just gives you an idea of how many cells we have. We

actually have on the order of, and you know it's obviously

not an exact number, but actually in the human body,

there's on the order of 100 trillion cells.

And if you look at it that way, you say on average, one

thousandth of your cells replicate each day, but the

reality is some cells don't replicate that frequently at

all and some cells replicate much more frequently.

Just to take a little side note here, this gives you an

appreciation, I think, for the complexity of the human body.

I mean we think of our own world economy and world

society as so complex, it's made up of 6 billion humans.

100 trillion can be rewritten as 100,000 billion cells.

And each one of those 100,000 billion cells are these huge--

I know I shouldn't use the word huge-- but they're these

And we'll talk about all the different organelles they

have, and we talked about cellular replication, DNA

So these things aren't jokes and they have all of these

complex membranes that take things into them.

They are creatures to themselves, but they live in

this complex environment or society that is each of us.

So that's just a side note just to appreciate how large

But you can imagine, and this is how I got off on this

tangent, if we're making on the order of 100 billion new

cells every day, you're going to have a lot of mutations,

and maybe some of the mutations, you know I said

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Cancer | Cells | MCAT | Khan Academy

essentially

eventually

recognize

eliminate