Alright, Reactions seven and eight. Final two reactions the citric acid cycle. First, we have a few more race delta G, close to zero, and it is going to take few more. Eight. Make mallet. Mallet can have an L or a D form. We're gonna make l mallet. So important to note here is L mallet, and it's going to add in water. Basically. So here. I've just shown, you know, water being added in is one whole thing kind of simplifying the whole reaction a little bit. Um, but if we were to look at the mechanism, you actually see that water is added in two parts First is O H minus, then as a church plus and we're basically going thio or reduce this double bond and put a little alcohol group right there. And then finally, Malay di hydrogen ace. Uh, look at that Delta G, right, 30. That's big, right? Big positive. Delta G. Well, turns out in biological conditions, because, remember, this is the Delta G, not prime in biological conditions. This is this Delta G is actually close to zero. So this reaction is also one of those easily reversible ones it produces an eight th and it takes mallet and turns it into ox alot acetate, and we are ready to start the cycle again. So let's finish up our discussion of the citric acid cycle with a little bit of accounting. Right. Let's talk numbers so N a D H will ultimately produce 2.5 ATP in oxidative phosphor relation. Uh, don't worry about the specifics of that. That's gonna be what we cover in the next unit. For now. Just just know that any D H makes 2.5 a t p and F A D H two makes 1.5 80 people talk about why there's a difference there in the next unit. Andi. It'll make tons of sense. It's not one of those arbitrary things. There's a reason, and it will make sense once we go through it. So, uh, one important note is that any D. H the th that's generated in, like Hollis iss right by glycerol to hide three phosphate di hydrogen that can actually generate 1.5 or 2.58 p, and it depends on where it let's say where it enters in metabolism. Uh, you know, downstream where it enters in. You know, again, I don't need to worry about specifics. Uh, but basically, uh, depending on the path that it takes, it will either produce 1.5 or 2.5 a t. P. So a little bit of a toss up there. And that is why we say that one glucose yields 32 ATP Because it's because of this discrepancy, right? For every any th That's a difference of one at P. And remember that for glucose, you're gonna generate two of these n a. D h. Because the sky is going to do the reaction twice for each glucose molecule, right? There's me to three carbon molecules going through anyways, uh, so that would ultimately turn into a difference of two a teepee, depending on what happens to those and a th is now. You don't really need to worry too much about that. Let's focus on the important stuff. Where is all of this? A teepee coming from So again you're going to get 5 to 7 from like Hollis iss, right? And there's a two a teepee difference here because of these and a D h is, um So, uh, you know, let's say that Let's just say for argument's sake that they're making 2.5 80 piece. That's 5 80 p. And then you also generate, uh, 4. 80 p from black Allah Assists. But you use up too, so there's a net to 80 p. So that's where our 80 p from Glen Collis is is coming from, um, Peru. But oxidation, you make 5. 80 p, right? Because Peru, but oxidation for one glucose will generate to an A D. H. And that will make 5 80 p ultimately. And then you're actually gonna produce 20 from the citric acid cycle. Big money, right? That's why citric acid cycle, um, and on aerobic respiration is so important when you think about it. Terms of ATP yield versus like Allah assists like Hollis is, is so much less energy efficient. It's it's just phenomenal. Your your cells literally wouldn't be able to provide enough energy for your body if it weren't for aerobic respiration. Um, I mean, really not too hard on it. But just to put it in perspective, your body basically cycles kg of a t p a day. That means that you generate and burn about 50 kg of eight p a day. Go check out how much that is of your actual body weight. It will astonish you anyhow, Moving on citric acid cycle for one glucose, right. We're gonna have to Acetyl coa is going through the cycle, so we're going to generate six and a d h two f A d h two and either to a t p or two GTP, and that's gonna yield a total of 2080 p. So that is where we get our 32 32 80 p total from these processes. Now let's talk a little bit about regulation of the citric acid cycle. Generally speaking, the citric acid cycle is regulated by the energy poor and energy rich molecules involved in respiration. So energy rich molecules azi. We've mentioned before stuff like a T P and N a T h right. An energy poor molecules. Stuff like a m p a d p n N a d plus. So let's look at our big player enzymes, right? Piru di hydrogen ace. And then the enzymes for reactions 13 and four from the citric acid cycle. Our drivers right? Peru di hydrogen aces inhibited by 80 p. Uh, right. A c Delco A No surprises there. And n a T h. All right. All very, very logical. Right? Uh, the stuff that it produces is going to inhibit it, so it doesn't overproduce. Likewise, The stuff that it uses to carry out its reaction stimulates it because, you know, if it needs thio, start carrying out its reaction kick. It's butt into gear. It's going to get the signal from the build up of all this stuff, meaning that these molecules have been consumed. And now we're left with this. We need to make more. All right. Moving on. Citrate Synthes inhibited by any th suck in Elko. A citrate. It's direct product. Right? Citrate. Synthes makes it traits. Direct product inhibits it. Uh, took milk away comes downstream and citric acid cycle, but it still will feed back to the first step of the cycle. Pretty smart. Right. Have a later reaction feedback on the first one. Do you have multiple feedback points in your citric acid cycle on It's also inhibited by ATP and it's stimulated by a deep isis citrate di hydrogen is inhibited by a teepee stimulated by ADP. Hopefully no surprises here. Alfa Kita Glue Torri di Hydrogen is complex, inhibited by any D p a n e d h rather and soeken ill co A. So hopefully this regulation stuff just seems very logical to you, right? Like it's kind of common sense type stuff. You know, I don't think you need to really know. Like all the specifics memorized all the specifics. I think it's more important that you just kind of understand the general idea that the products both the direct products and the downstream products tend to inhibit and the the reactant tend to stimulate last thing. Gonna talk about these? An operatic reactions? Um, these reactions air used to generate oxalate acetate to replace the loss of except, er molecules from the citric acid cycle. So the molecules of the citric acid cycle, like Alfa Kita glued a rate section eight. Um, you know, oxalic acid state to, for example, these can all be used Aziz bio synthetic precursors, and they'll make many amino acids. Some can actually be used to make other things, and what's important is that if they're pulled away from the citric acid cycle. It's very likely that they will need to be replaced at some point. If this, you know, the cycle needs thio output higher production. So thes an operatic reactions air basically just reactions used to generate xolo acetate. And remember, Axel acetate is made in step eight of the cycle, but steps 876 and five can be reversed. Right? We could go backwards so we can produce up to, you know, suck in Elko. A, um sorry. We can We can produce up to suck Conoco way to regenerate whatever molecule of the cycle we need. Um, you know, so any of any of these guys, for example, or, you know, if we, uh, yeah, I mean, just the basic ideas that you can you can reverse these reactions so that you can produce, like, male, eight fume rate. Soeken eight took milk away. Whatever it is, you can't reverse the reaction that produces took in. Elko aches. It's one of the drivers. All right with that, Let's flip the page
