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Review 3: Pyruvate & Fatty Acid Oxidation, Citric Acid Cycle, & Glycogen Metabolism

Fatty Acid Oxidation 2


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unsaturated fatty acids sometimes require a little helping hand with beta oxidation, and that is because they sometimes need to move that in around. Right. So remember, trans confirmations air. Okay, but sis have to be rearranged. Furthermore, we're gonna want that double bond like we saw before. We're gonna want it between the two and three carbon on the molecule. Um, now, with what we're about to talk about, I just want to say that you don't obsess over the details. Just try to come away with Sort of, like the general understanding of the generalities. So, uh, you know, let's take a look at this figure here. Basically, we're doing beta oxidation chipping away at this until boom, we get right up close and personal with those double bonds. Now, those both those double bonds air in the CIS form, so both of them are unacceptable. Additionally, we want this double bond to be between the two and three carbon. Right now it's between three. And four. So we're gonna use a nice some race, right to actually move that over into the right position. And then from there, we can just do normal beta oxidation, right? Chop it off. Here is the catch. The catch is, if you do this, you're not going to generate an F a. D h from that round of beta oxidation. Right? Because the first step of beta oxidation is introducing that double bond and reducing F A D. Right. Well, you didn't introduce that double bond. You just moved it over. So you're not gonna make an f a D if you do that. All right. Just something Thio be aware of and keep track of. If you're thinking about the beta oxidation off various molecules, alright, so moving on. If you have multiple points of unsaturated in in a particular arrangement, it might actually prevent in I som race from being able to take care of the issue. Right. So right here, Uh, that can't be dealt with by a nice SOM race alone. So what's gonna have to happen? So we're gonna have to use any DPH to reduce our in, and then we can deal with it, so we're gonna have any DPH come in and n a D. PH writes just like an a d h. It's an electron carrier. It's gonna drop off its electrons to reduce that bond and we're gonna be left with N A d p plus. Okay, And then we'll go through ur depending on the confirmation here, we can actually just move this bond over right and do beta oxidation in some situations. You you might not have a new arrangement like that, and you might reduce with n a d pH and then actually have Thio create the double bond and generate an f a D h two so odd numbered fats odd numbered fatty acids will end up with, uh Well, if we have an even number of fatty acid right in our last round of beta oxidation, we're gonna have a four carbon molecule that's gonna get chopped into two acetyl coa is right both of those two carbon molecules. Uh, if we have an odd number fatty acid, that last step is going Teoh a five carbon molecule and we're gonna chop it into a NASA telco, a two carbons and a pro bono Elko A just three carbons. Now ask Kyoko a. That's fine. We can work with that, right, but but propane oil co A. We're gonna have thio modify that molecule before we could do anything with it. And what we're gonna do is we're gonna add CO two to it. It's actually gonna cost ATP, and we're gonna convert it into Second Ill. Co A. Hey, I remember that molecule that's used in step five of the tri car box like acid cycle or the citric acid cycle. I abbreviated citric acid cycle. Here is T C A. But that's just the citric acid cycle. There's actually three. Well, wait, let's get messy. It's actually three names for the citric acid cycle. You have the citric acid cycle, the Krebs cycle and the tri carb oxalic acids. Like same thing. T. C. A is often abbreviation for this cycle, though, Um, anyhow, moving on. Last thing we're gonna do is we're going to take a look at this molecule, Palm Palm Medic acid and we are going thio put it through beta oxidation and see how much ATP we generate. This is gonna be good exercise for sort of tracing the logic of the various metabolic pathways we've been talking about. So I'm gonna hop out of the image here, free up some space, you can see the molecule, and here we go So Paul Mitic acid, that's 16 carbons could see it right here. And I'm actually gonna show where all the cuts they're gonna happen. Now, if you remember before, there's, like, a little simple rule you can think of to figure out how many acetyl coa way you're gonna produce right on how many rounds of beta oxidation you're gonna go through. And that little trick is you do half the number of carbons in the molecule minus one. Right, So here we have 16 carbons. Divide by two. That's eight minus one. So seven rounds and this is going to produce seven Acetyl Coetzee's right. So from beta oxidation alone, we're going to generate seven f A d h s, which will lead to 10.5 ATP's, and we're going to generate seven n a. D. H is which will lead Thio 17. ATP's. Now these seven asked Alcoa's. They're gonna go through the citric acid cycle right when I'm sorry. Whoops. This is eight acetyl coa is sorry. Seven rounds of beta oxidation. Eight acid steel co is my bad guys. My bad. Sorry if you caught that. Um Anyways, one acetyl coa a going through the citric acid cycle. Yields one F a D. H two and three and a D h as well as 1. 80 p or GTP. So eight s Steel Co is gonna make eight f a d h right, which is 12 ATP n a d h. That's gonna make 24 of those guys, right? Which is gonna lead Thio. But let's see, 60 ATP. And don't forget that we're also going to be producing eight ATP or GTP. Same thing. We're going to count them right from the citric acid cycle. So total we're gonna make how much a teepee 108 ATP by putting Paul medic acid through beta oxidation. That's a ton of tp, right? Pretty crazy. If you're wondering just if you're wondering like, hey, wait, that's so much energy. Why do we use glucose? Is and not just use fat all the time. The answer is, actually, if you divide by the molecular weight, there's more energy per weight in glucose than there is in fatty acids. Even though one fatty acid can generate that, you know, a ton of ATP. All right, that's all I have for this exam review. Let's move on to some exam practice questions