Fatty Acid Oxidation 1 - Video Tutorials & Practice Problems
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Fatty Acid Oxidation 1
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as we've mentioned previously, fats can be used for energy storage and they can be broken down into glycerol and fatty acids and fatty acids can be converted into a C Delco A through beta oxidation. We're gonna cover that process now, but before we get there, we need to talk about how fatty acids actually get into mitochondria. Um, before I get ahead of myself, though, I also do want to mention that fats can be used for water storage as well as energy. And this comes into play mawr with creatures that live in desert environments, for example, camels. Most people incorrectly think that camel's humps air filled with water there actually filled with fat that the camels can convert into water. Anyhow, Uh, before we get to the fatty acids real quick, just thio harken back to what we talked about In the previous unit, glycerol can be converted into D. H. A P, which will be converted into G three p, and the's are substrates of like Hollis ISS. The CA Tabal ism of glycerol yields 1 80 p per glycerol and two and a DHS, which is great if you're trying Thio, I do respiration but that's a lot of N a D h, um, to be produced. So it makes it a non for mental sugar. Basically, uh, if you recall from previous unit, you know, it produces Maurin a d h. Than the reactions come get rid of Essentially. So it, uh, it's an unsustainable sugar to use in fermentation. Anyhow, moving on to the main stuff. Let's talk about those fatty acids. So they undergo beta oxidation to enter the citric acid cycle is a seal Coetzee or in some cases, took milk away. We'll get to that later. Fatty acids have to you Excuse me. Sorry. Fatty acids have to first be activated by being converted into fatty sl co is. And, uh, this reaction is not pictured here, but what you all you really need to know about it is they they add a co a onto the molecule, and it costs to a teepee. Sort of. I have that in quotes. Basically, it costs, uh, one ATP and then you break both anhydride bonds. So, uh, your professor likes to think of it. Is costing two ATP, just you know, it's in his. It's in his lecture notes. That's how he thinks of it. So in case it comes up, you know, to a teepee. But that's what the quotes air for. It's really just breaking the two acid him anhydride, bonds. Um, anyhow, this molecule, this fatty sl co. It will be transported into the mitochondrial matrix. But it has to first be bound Thio carnitine. And once it's bound Thio, by the way, it's bound to carnitine by Carney till a cell transfer race one. So here is C A t one. This molecule right here is going to combine the SL co and carnitine and send that hassle carnitine through this anti porter and let me get out of the image here. This anti porter, uh, will pass the S L carnitine into the mitochondrial matrix and will move a carnitine, a rake just plain carnitine out the other way. Okay. And once the a C l carnitine gets into the mitochondrial matrix, it's actually going to be broken back down into a psycho and quarantine, and that is going to be done by carnitine Essel transfer race too. So see a T to this enzyme right here. Okay. So Ah, this is often called the carnitine shuttle, and it's because carnitine isn't really consumed in the process. It just kind of shuttles back and forth to move these fatty acids into the matrix, where they can undergo beta oxidation. So bad oxidation as hopefully you figured out at this point occurs in the mitochondrial matrix, Right? That's why we're bringing those fatty acids in. And beta oxidation removes to carbon units at a time, and it removes them as a Seattle co a on these air being clipped off again from the fatty SL Co. A that we brought into the mitochondrial matrix. Now, uh, it's basically beta oxidation is basically made up of four repeating steps. And as you can see here in this image, well, first of all, these names are not in English, but that's fine. You don't need to worry about these names. Uh, you don't really need to worry about the enzymes involved, you know, memorizing all the specific reactions they do. So what you should know is the basic things that are happening in each of these four steps. So first, what's going on right here? This is our fatty acid. Um, let me actually scroll down a little so you can see this better. So here we have our fatty acid. Here's our CO A. That's a least the same in whatever language this is actually not sure about, Um, leave a comment if you know, I'd be curious. Anyways, the CO and the fatty acid are combined into that fatty SL co A right here. This is our fatty Aysal co A. That is the activation step. Now we have beta oxidation. Alright, so first thing that's gonna happen is we're going thio oxidize on a main to an e. Okay, we're going to oxidize an A to an e in and it's a nasal co a d hydrogen ace. That's gonna do this and it works, basically, just like soeken eight d hydrogen ace. Right, So it's gonna, uh it's gonna take f A D and reduce it to f a. D. H two in the process. And you can see really what it's doing is it's it's introducing a double bond right here. Right, So there is the double bonds in the molecule right now. We are ready for step to you and do take note that that double bond is between carbon too, and three on this molecule and it has a trans configuration. These air both both important things to know. You'll see. Why momentarily. All right, Step two. We add water to the scene to form an alcohol. Okay, that is carried out by, you know, well, co a hydra tastes. And it's kind of like the conversion from Fumar eight Thio may late and you can see here is our new alcohol group. Right then. Step three. We oxidized the alcohol You can see there it has been oxidized. Thio, I'm sorry. Circled the wrong one. There has been oxidized to carbon Neil, and this is carried out by a beta hydro. Excuse me, beta hydroxy sl co a d hydrogen ease with a mouthful and that's gonna take n a d plus and convert it into any D h. And this is like Malay di hydrogen. It's okay. So notice that they're these parallels between these particular steps we're seeing here and reactions that we see in the citric acid cycle. Okay, These are important parallels to bear in mind. They can come up on test questions sometimes. Okay, So last thing that's gonna happen, step four is violates. Is going Thio, cleave off Uh, the acetyl coa A and add a CO a to the new end of the fatty acid. And, um, you can see that here is our acetyl coa A. Here it's come off here is our new co. And that's gonna be attached onto the new end of our fatty Essel CO A. And then that is just going to go back through step one and keep repeating the cycle until we are left with this molecule. And guess what happens when this molecule goes through Step four. Well, this gets broken and you get left with two acetyl COA is right, because in this last step, we add a CO A to the new end. Well, guess what? The new end is only two carbon to carbon molecule and you add that co A on your left with the Segal CO. A. So basically with beta oxidation like, let's say you have a 10 a 10 carbon fatty acid chain 10 carbon chain. It's going to go through five rounds. I'm sorry. Four rounds of beta oxidation, right, because you have here are five to carbon units, right. Each of these air two carbons So you're gonna have one round, two rounds, three rounds and then the last round right there, Right? You're not gonna do another round there. So if it's ah, so that, you know, kind of like little trick the rule to remember, It's sort of like half the number of carbons minus one, basically. Anyhow, let's turn the page and talk about when things don't work out as cleanly for beta oxidation as they did here. Right? Remember this. We're kind of talking about perfect scenario. What if we have a uneven fatty acid chain, a chain fatty acid chain that has an uneven number of carbon? I'm sorry. An odd number of carbons. What are we going to do then? Well, let's flip the page and find out.