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Catena di trasporto Electron

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After being done with glycolysis and the Kreb's Cycle,
we're left with 10 NADHs and 2 FADH2s
and I told you that these are going to be used in the Electron Transport Chain
and they're all sitting in the matrix of our mitochondria
and I said that they're going to be used in the
Electron Transport Chain in order to actually generate ATP.
So that's what I'm going to focus on in this video--the Electron Transport Chain.
And just so you know, a lot of this stuff is known,
but some of the details are actually current areas of research.
People have models and they're trying to substantiate
the models, but things are happening at such a small
scale here, that people can just look at the evidence, some
of it of which is indirect, and say this is probably
what's happening. Most of this is very well established,
but some of the exact mechanisms--for example--how exactly some of the proteins work--
aren't completely understood. So I think it's very important
for you to understand that this is kind of at the cutting edge.
You're already there.
So the basic idea here is that the NADHs--and that's where
I'll focus--FADH2 is kind of the same idea, although
it's electrons are at a slightly lower energy state, so they
won't produce quite as many ATPs. Each NADH--maybe I'll write it here--
each NADH is going to be, as you'll see, indirectly responsible
for the production of three ATPs, and each
FADH2, in a very efficient cell, in both of these cases,
will be indirectly responsible for the production of 2 ATPs.
And the reason why this guy produces fewer ATPs
is because the electrons that he has going into the Electron
Transport Chain are at a slightly lower energy level
than the ones from NADH.
So in general, I just said indirectly, how does this whole business work?
Well in general, NADH when it gets oxidized
So, NADH... remember Oxidation is the losing of electrons
or the losing of Hydrogens that happen to have electrons
we can write its half reaction like this
its oxidation reaction like this
you'll have some NAD plus which you can then go and use
back in the Kreb cycle and in glycolysis
you have some NAD plus, you'll have a proton right
a positive hydrogen ion is just a proton
and then you'll have two electrons
This is the oxidation of NADH
Oxidation of NADH
It's losing these two electrons
Oxidation is losing electrons. OIL RIG
Oxidation is losing electrons or you can imagine
it's losing Hydrogens from which it can hog electrons
Either one of those is the case
Now, this is really the first step of the electron transport chain
These electrons are transported out of the NADH
Now, the last step of the Electron Transport Chain is you have 2 electrons
and you can use the same 2 electrons if you'd like
2 electrons plus 2 Hydrogen protons
now obviously if you just add these two together
you're gonna have 2 Hydrogen atoms
which is just a proton and an electron
plus one Oxygen atom or so I could say
one half of molecular oxygen
that's the same thing as saying one Oxygen atom
and you're going to produce
If I have one Oxygen and two complete Hydrogens
I'm left with water
and you can view this we're adding electrons or we're gaining electrons
to Oxygen. OIL RIG - Reduction Is Gaining electrons
So, this is the reduction of Oxygen to water
This is the oxidation of NADH to NAD+
Now, these electrons that are popping out of--these electrons right here
that are popping out of this NADH
When they're in NADH, they're in a very high energy state
and what happens over the course of the Electron Transport Chain
is that these electrons get transported to a series of--I guess you could call them--
transition molecules
but these transition molecules -
as the electrons go from one to the other, they go into slightly lower energy states
and I won't even go into the details of these molecules
Coenzyme Q, Cytochrome C
and then they eventually end up right here
and they're used to reduce your Oxygen into water
Now, everytime an electron goes from a higher energy state
to a lower energy state--and that's what it's doing over the course of this electron transport chain
it's releasing energy
so, energy is released from when you go from a higher state to a lower state
with these electrons in NADH, they were in a higher state than they are when they bond to
Coenzyme Q so they release energy then they go to Cytochrome C
release energy
now that energy is used to pump protons across the inner membrane of the mitochondria
this is all very complicated sounding and you know, this is the cutting edge
this is the cutting edge so it may be should sound a little complicated
so, let me draw a mitochondria just so you know where we're operating
that's its outer membrane
and then its inner membrane will look like that
maybe it looks just like that
now let me zoom in on the membrane
so let's say if I were to take-if I were to zoom in right there
so if I were to zoomed that out, that box will look like this
you have your cristae here--now I'm gonna draw it thick
right, so I'm zooming in--this green line right here--I'm gonna draw it really thick
colour it in with green just like that
and then you have your outer membrane
and this outer membrane, I could do it up here
I'll just colour it in. You don't even have to see the outside of the outer membrane
right here, this base right here, this is the outer compartment
and then we learned in the last video, this base right here is the matrix
this is the matrix
this is where our Krebs cycle occurred and where a lot of our NADH
or really all of our NADH is sitting
so what happens is, everytime, NADH gets oxidized
to NAD+ or each of the and the electrons keep transferring from one molecule to another
it's occurring in these big protein complexes