Electron Transport Chain Overview of the Electron Transport Chain
Electron Transport Chain
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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
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