All right, well, let's take a look at FADH2 then. So here's an interesting thing. Remember when we go from succinate to fumarate, and during the process, we have FAD. and FADH2. Complex 2 is actually the enzyme that facilitates the 6 and 8 being converted to fumarate.
And so what happens in this process while we say that we produce FADH2, the reality and just Bear with me here a second. The reality is that this process kind of happens all simultaneously and the electrons are kind of automatically given to coenzyme Q. So while we're saying, yes, we make FADH2, what happens is that FADH2 essentially is part of complex two. It's like kind of embedded in part of the enzyme. Okay, so what happens then is the FADH2 that's made in that reaction from succinate to fumarate essentially is going to give its two electrons to complex two, which then now the FADH2 would be oxidized back to FAD, and we get the two protons again.
So if you noticed, we've completely bypassed complex one, and we know that complex one pumps four protons into that inner membrane space. Electrons don't go backwards. They're always going to go towards complex four.
All right, so those electrons are going to go then from complex two to that coenzyme Q, totally bypassing complex one. And then they're going to get handed off here to complex three, like we saw before. And then to cytochrome C.
And in the process of that, now we're seeing four protons pumped against the gradient. And we know that NADH had enough energy to pump four at the first, four at the second, and two at the third pump. We've skipped the first pump.
And so now we're only taking advantage of pumps two and three, which is complex three and complex four. So we can pump four here. And then when these get handed off here, and then ultimately handed off to the oxygen and the two protons and the two electrons to make water, we get two more. Bumped in there. So that's six protons, right?
Now we said that how many protons does it take to make one ATP? Four. So if we have six, six isn't enough to make two ATP. It's really only enough to make one and a half. But you can't make a half an ATP.
And besides, there's always protons in this matrix. So the original six are going to go through the ATP synthase, plus an additional two, because they're always moving through. Therefore, we say that FADH2 has enough energy to make two ATP.
Correct. The short answer is the reason why NADH has...... can make more ATP than FADH2 with the energy that's in it is because NADH powers three pumps and pumps ten protons to the intermembrane space whereas FADH2 bypasses pump one and only has energy to power two of those pumps and only six protons are pumped in the intermembrane space.
And because of the fact that less protons are going through ATP synthase, then there's less ATP that can be made from that original electron energy. That's what I'm looking for essentially for that answer on the test. But I want some details.
You don't have to tell me the names of these complexes. You can just say there's three pumps. NADH hands its electrons off to pump one. pumps four protons, and then pump, when the electrons are passed to pump two, it pumps four protons, and then when they're passed to pump three, they're only two protons, and then those protons have to go back through, and when they do, those 10, they're equivalent to three ATP. But FADH2 bypasses pump one, only powers pumps two and three, which only pumps six, et cetera, et cetera, et cetera.
Those are the kind of details I'm looking for. If you want to throw in the names of the pumps, great. You don't have to.
Or the names of the complexes, you don't have to. But I want you to be able to articulate to me, in your words, why we get different amounts of ATP. And don't leave questions blank. Put something, even if you're drawing a blank.
Try to bullshit your way through it, because you never know, you might get a couple things right and get some token credit. Better than zero. You'd be surprised how many students just don't even bother to do any of the written questions, even if they're short answers.
The bulk of the test is multiple choice, and some students just want to take their chances with that. Totally up to you what you want to do. It's easier for me to grade.
That's what I'm looking for for that answer. Let's look at our numbers here again. Do we, I'm just going to write these down real quick.
And again, these are per glucose. Oops, that should be a zero here. That's a zero. So that's where we started. We had 4 ATP already produced and we had a total of 10 NADH and 4 FADH2 and if we multiply those by their equivalents we get 30 ATP from NADH and we get 4 ATP from FADH2.
and when we add up our atp totals we have 34 plus our original four which is 38. so you know technically we didn't use any so we have a net production of 34 atp if we add up all of our net atps that's 38 and so that's where our 38 come from That's an ideal perfect condition, which doesn't happen. I am recording this. I'll post that this afternoon. It should be fairly easy to edit and get on there for you. Here's what I would recommend you do for homework, and we can go over this and talk about this in groups on Tuesday, is page 15 and 16 of the packet I gave you on Tuesday, cellular respiration math.
There's six prompts. And you're going to assume that 12 molecules of glucose get completely and fully oxidized by aerobic respiration, meaning 12 glucose are going to start in glycolysis, go all the way through. Those pyruvates are going to go all the way through the PrEP reaction, all the way through Krebs cycle, all the way through electron transport and through the ATP synthase, so oxidative phosphorylation. With that in mind, you need to answer those six questions.
I'm very specific on these questions. How many total ATP are produced in glycolysis and the citric acid cycle? I'm not talking electron transport.
I'm just talking about only the ATP produced in those two sets of reactions from those 12 glucose molecules. Assume that the initial investment of ATP required has not been deducted from the actual amount produced. So I don't want the net ATP. I want the gross, the total. Question two, how many FAD molecules are reduced to FADH2?
You got to think about what does that mean and where does that take place? And if I have 12 glucose, what does that mean? How many carbon dioxide molecules are produced from the prep reaction only from those 12 glucose? Well, one glucose is equal to two pyruvates.
two pyruvates when they go through the prep reaction produce two carbon dioxide. Well I got 12 glucose so what does that equate to? You will have to do this on the test.
It's not difficult. There's only one question where you have to give me four answers because I ask you for four different things. Okay question four. How many ATP will be produced from the NADH generated in the prep reaction and the Krebs cycle?
So that means that I'm not talking glucose. I'm just saying prep reaction and the Krebs cycle. When those NADHs, just the NADHs, go through the electron transport oxidative phosphorylation, assuming 12 glucose, how many ATP do we get?
So you got to think about first, well, how many NADHs are we going to get for 12 glucose just from the prep, just from the Krebs cycle? And then you got to think about, well, this many, now how many ATP are we going to get from those? I know it seems kind of silly, but it's forcing you to think about all these processes and where these things are produced and the relationship between one glucose and two pyruvates and breaking it down and looking at little pieces.
All right, five, how many net ATP will be produced from Everything, glycolysis, the prep reaction, Krebs cycle, and oxidative phosphorylation. Assume the investment of ATP has been deducted from the actual amount produced. And then six, how many total protons will be pumped in the intermembrane space during oxidative phosphorylation? Again, assuming 12 glucose molecules. I would like you to make an attempt at that.
It's not hard. It's just a little bit of math and proportions. I will give you, let me try to give you a little hint. I would say break it up into three chunks. So let's say question one.
You know what? Let's do question one together. Let's do question one right now. So we want to know how many, we got 12 glucose, right? Okay.
So we know that how many total ATP do we get from one glucose molecule? Now this is glycolysis. We'll start with just glycolysis. How many?
So how many ATP do we get from one glucose just from glycolysis? Net, or sorry, total? Four, okay? We're not concerned for this question about that initial investment.
All right, so four ATP is equivalent to one glucose. How many glucose do we have? Twelve, all right, so twelve glucose molecules then. If I multiply all the top numbers together and divide by the bottom numbers, because the glucoses are on opposite sides of the line, I can cancel them out. And so the units I'm left with are ATP.
So 4 times 12 is? 48, right? So just from glycolysis of those 12 glucose alone, I get 48 ATP. Well, that's not the answer to this.
That's part of the answer, but that's not the answer. Now we got to figure out how many ATP we get from the Krebs cycle. Well, let's set that up this way. So we know that we get one ATP. For every one pyruvic acid, right?
So pyruvic acid comes in, it's oxidized to acetyl-CoA, acetyl-CoA enters, we get one turn of the citric acid cycle, and that gives us one ATP, right? All right, well, how many pyruvic acids do we have per every glucose molecule? Two.
We have two pyruvates. per every one glucose. And how many glucose do we have that we're saying we have to follow through?
12 glucose. So we can cancel out our like terms. So cancel out the two pyruvic acid units, cancel out the two glucose, multiply all the top numbers, divide by all the bottom numbers. 1 times 2 times 12 is 24. Divided by 1 is 24. So we get 24 ATP just from the Krebs cycle from those 12 glucose molecules.
The question was, how many total do we get from glycolysis in the citric acid cycle? Add those up. What do we get?
72 ATP. Now, if you can think about how to set these proportions up like this for the rest of them, you should be able to figure out how to do these. You know, you can assume that one carbon dioxide is equivalent to one pyruvic acid in certain instances. You can assume that, and maybe you won't need it, maybe you will, that one acetyl-CoA that enters into the citric acid cycle is equivalent to three carbon dioxides.
Or sorry, two carbon dioxides. Oops. Or you can assume that for every pyruvate that goes through the prep reaction and the citric acids are Krebs cycle, we get three carbon dioxides for every pyruvate. But you got to think about what reactions and what you're talking about.
I wrote three carbon dioxides for one pyruvate. This would be for the prep and the Krebs cycle. This one over here would be just for the prep reaction. This here would be just for the Krebs cycle. Okay?
I'm very specific on the test when I mention these reactions. All right, so I would do, what page did I say that was? 15 and 16? And then I also think you should do page 17. This is listing all these different events. All you have to do is take one of the numbers, find where it fits, and just write the number in the box.
You don't have to write the actual statement. But think about it. And we will go over those on Tuesday as well. I do have an answer key.
I will post it on the screen on Tuesday. We'll go over that. We'll go over the math. We will go over beta oxidation and the rest of chapter 3 and maybe have time to do a little bit with chapter 4.