- This might be one of my
favorite things in all biology.
This--
take a look at this and tell me
where does the electron
transport chain happen?
Use my little diagram
as a guide,
because of you look at this,
you'll be like, whoa,
really?
Just like all our other
pictures that I'm showing you,
it's super complex.
We're going to look,
I'm going to draw you a picture
of it in Wendy style,
but this is taking place
in the cell membrane
of the mitochondria itself.
It's actually taking place
in that inner folded
mitochondrial membrane.
And the inter membrane space,
between my two membranes,
is really important
to the function
of the electron transport chain.
All right, let's draw a picture.
Here's what I'm
going to tell you.
We might as well
have some visual
that allows us
to appreciate the fact
that all of our electron
carriers are going
to the electron transport chain.
They're headed there,
they're on their way.
And we're going
to draw a picture
of what they're going to find,
hey, we can't go that way,
there's no paper there.
We can go up.
We're going to draw a picture,
ready?
And it's color coded,
and it's color coded to match
the other images that I've
drawn elsewhere.
Okay, this, I'm going to draw,
I can't help it.
I'm going to draw you
a mitochondria,
and here are my two membranes,
are you in agreement?
And I'm taking a little slice,
like this, okay?
So I've got
my cytoplasm up here,
my outer mitochondrial
membrane is purple,
and then look at how I'm
going to craw my blue
inner mitochondrial membrane.
I'm just going to draw
it in a flat line,
and I'm going to do that just so
you can visualize that I've
just taken a little slice,
and this flat line,
actually,
even though it is
actually curving,
I've zoomed in so much that
it appears to be a flat line.
Now, inside here is the
mitochondrial matrix,
and in-between these,
remember, is the
inter membrane space.
Inter membrane space.
All right, and all of
these are important
anatomical locations to
understand the function.
Who is coming to this
electron transport chain,
[inaudible]
Well, our electron carriers,
and what do they have?
There were twelve of them,
and every single one of them
is carrying two electrons.
So watch, and there
are twelve of them.
Twelve of them
coming to do a job.
I want you to look at this.
I'm going to draw a
totally diagrammatic
view of a set of proteins that
are embedded in the inner
mitochondrial membrane.
I'm going to draw another one
right now while we're at it,
because I can't help it.
This one is just about the
coolest thing that ever existed.
I'm going to draw
it in here now,
and then I'll tell you
what happens to it.
That thing is so awesome.
All right, watch.
First of all, in comes
an electron carrier,
the electron carrier delivers
these high energy electrons.
Hands them off, it's like,
hey,
electron transport
chain protein,
I'm going to hook you up with
some high energy electrons.
That's the first
thing that happens.
This protein's like, "rock on,
I'm cool with that.
Go ahead and hand me those
high energy electrons."
And then, those high
energy electrons,
make sense they
have energy in them,
guess what this guy does?
This protein captures
some of the energy in those
high energy electrons and says,
okay, I'm going to use some
energy to do some work,
and the work that is going to
be done is super random.
Well, it will appear
random to you.
You're going to be like, dude,
really?
What is this?
Energy in the high energy
electrons is going to be used
to pump hydrogen ions
into the inter membrane space.
And they're going in against
their concentration gradient.
That's how you know it's
going to require energy.
Who is providing the energy?
The high energy electrons.
They came from these carriers.
I think of it as passing
these electrons downhill.
Now watch.
This first protein uses
a little bit of energy
from these high energy electrons
and passes them off
to the next protein.
Which then captures--
there's energy that is released.
I think of it--
I draw them to have like
kind of a potential energy,
like you're passing
these electrons downhill.
And so you're losing potential
energy in these electrons
as you pass them
from protein to protein.
I guarantee that there is
a very clear chemical
explanation for this.
I just think of it as
passing them downhill.
And when you pass them downhill,
energy is released,
and we capture that energy
and use it to pump protons
into this inter membrane space.
My second buddy buddy is going
to do exactly the same thing.
Using the energy that comes out
of these high energy electrons,
it's going to pass them down--
I can get orange,
I really can, there we go,
pass them down,
and each time we're releasing
a little bit of energy
that is captured and used
to pump more protons
into this inter membrane space.
All right, really?
IS anybody like going,
why are we doing this? I am.
Let me tell you! Oh my gosh,
this is a true story.
This is not a windification.
Now we've got a whole bunch
of protons in this space
and where to do they want to go?
You're like proton party,
I'm sick of this party,
get me out of here.
They want to get out.
And this molecule is called
ATP synthase.
ATP synthase, you're going
to think I'm lying and I'm not.
It's like a water wheel.
What?
It spins, and it spins
in a circle when every time
a hydrogen ion passes
through it,
there's a little thing in there
that spins and when it spins,
guess what it does?
Oh my gosh, this is so amazing,
it takes ATP+ P
and it produces ATP.
I am not lying.
This is what really happens,
oh my gosh,
that is so phenomenal.
So every time hydrogen ions pass
through, we're able to make ATP,
and in fact, it's like,
I don't know,
30 ATP molecules
from one molecule of glucose
in the electron transport chain.
Seriously?
Now, we had twelve of
these guys, and that's awesome.
We can actually keep
passing electrons
on as long as we have a final
electron acceptor.
And I'm telling you,
we need oxygen.
And I just keep on deciding,
I can't decide what
color to make it.
Oxygen is my final
electron acceptor.
And I want you to think about
this for just a second.
It's why you breathe.
It's why you need oxygen at all,
because you need oxygen to be
the final electron acceptor.
When oxygen grabs
those two electrons,
it'll also grab a couple of
random hydrogen ions
here and ultimately,
this is so phenomenal,
it produces water.
Are you serious?
Take a look at your
chemical equation,
and you will see that water
is one of the byproducts,
and oxygen is required.
If you don't have oxygen as
your final electron acceptor,
you're going to get a log jam,
and your electron,
your high energy electron
carriers aren't going to have
anywhere to put their electrons,
so the whole thing's
going to back up.
You're not going to
get all that energy,
because it is anaerobic
respiration, not aerobic.
As long as you have oxygen,
you have aerobic
respiration going on.
