Let's take a closer look at what's going on inside the complexes of the electron transport chain Complex one, which is also called any DHD. Hydrogen ease pumps four protons into the inter membrane space and has the prosthetic groups Flavin, mono nucleotide and iron sulfur proteins. Now any D H delivers two electrons too complex one, and it passes them again to Flavin, Monta Nucleotide. And then they move on to the iron sulfur proteins. And from there they get picked up by ubiquity known, which also takes two protons out of the inter membrane space. And then it gets reduced and it will go on Thio Complex three. But we will get to that in a moment. First, let's take a look at complex to which is sucking eight D hydrogen ISS. So this is actually an enzyme that is also part of the citric acid cycle, if you might remember, and it doesn't pump any protons. It does, however, contribute slightly if you think about it because it is going to you also pass its electrons on to ubiquity known right, and you become a known is going to pull two protons out of the mitochondrial matrix So even though it doesn't pump any protons, it is going to remove protons from the Matrix. And just to be clear, this is the intern membrane space. Okay, so it actually has f a D. As a prosthetic group. I know the image looks as though F a F A D or F A. D H two is external to the protein complex, but it's actually part of the protein complex. So it's a prosthetic group, right? The reaction with Soeken eight D hydrogen is is going to pass electron staff a d. H two, and it is going to pass electrons onto those iron sulfur proteins. And F A. D H two again will deliver its electrons to you pick one on which will become reduced and go on to complex three. Now it's interesting to note that there are actually three f A D entry points to you. Pick one on right. We have complex to which we just talked about. But we can also send F A D T v. Quinn on through beta oxidation. And if we use that system, we talked about just previously where n a. D. H will actually pass, it's electrons onto, um, a nef a d, which gives them to ubiquity on right. So there's actually three ways for F a D to give electrons to you. Pick one on and complex to is on Lee one of them. So just something to think about. Yeah. Now complex three or cytochrome B as it's sometimes called, pumps four protons into the inter membrane space and has a heem prosthetic group and iron sulfur proteins. And it actually has a pretty interesting thing that occurs with you. Pick one on, called the Q cycle, where essentially cytochrome C, which is ultimately what's going thio receive the electrons from you. Pick one on cytochrome C can Onley except one electron in a time, right can only move one electron at a time. You become known passes on two electrons at a time, though it actually has to pass on two at a time. It can't hold on. So essentially what happens is you have, and I just want to be clear that all the numbers in this figure are representing the net reaction of what's going on here. So I'm gonna talk you through how it goes step by step. So essentially you have just one just one reduced You pick winnin come in and drop both of its electrons off right And one goes to the iron sulfur proteins and then on to cytochrome C and the other takes a different route where it actually links up with another ubiquity known that gets reduced and actually comes back and drops off. It's electrons. So it has. Let me actually do it this way. I'm gonna do it's line in red. So this ubiquity home comes and drops on electron off that goes thio cytochrome C and another one that also takes this circuitous route. And again the cycle continues. So after this, you'd have another ubiquity and come in and this would repeat. But we're not actually being shown that in the figure. We're just being shown the net reaction for two electrons, right, because we had two electrons coming in from complex one or two. So we wanna follow their path through. So the net reaction of those two electrons coming in and those two electrons leaving via to cytochrome C is four protons get pumped through and you become known while it is performing this Q cycle, right? The ubiquitous owns that pick up that extra electron are going to end up taking two protons out of the mitochondrial matrix. So from here, cytochrome C is going thio, bring the electrons to their final stop, which is complex for or cytochrome C oxidase. Now this is gonna pump four protons as well in here. Let's let's be thorough, right? So let me jump out of the image here too, so you can see better. So Complex four is gonna pump four protons as well. And essentially the electrons are going. Thio, move from cytochrome C to these two coppers. You have these two coppers in complex for they're going to accept the electrons from cytochrome C. Um, what I'm showing here is that the two coppers can accept a total of four electrons from four cytochrome sees. You'll see why that's significant in a second, right? So now we're talking about what would have been delivered from Thio n a. T H or F A D H. To. And this is important to the numbers matching up to the reaction below we're gonna talk about. So anyhow, you have cytochrome c dropping off those electrons to the coppers. They moved through Complex four and what you wind up with is water being formed so complex for is going to take in. It's going to take in protons and oxygen, and it's gonna form water. So oxygen is the final Elektronik sector here, and it enters its most reduced form as water. And that is the end of electron transport. And I mean, you've got to think about this for a second. It's it's pretty amazing that, you know, this oxygen right here is the reason we breathe right. That is what we are taking in its This oxygen right here and the C 02 that were exhaling is the CO two that's coming off of the reactions in the citric acid cycle. I mean, that's pretty mind boggling, right? I just think it's so cool. Anyhow, with that, I'm done deking out and let's flip the page
