Hey, everyone. So in this video, we'll take a look at the total energy from fatty acids. Now here we're going to say to calculate the total ATP yield from the complete oxidation of a fatty acid, we must consider two things. First, we need to consider the ATP from Acetyl CoA oxidation within the citric acid cycle or Krebs cycle. In addition to this, we need to think about ATP from NADH and FADH2, our two high energy molecules that are in oxidative phosphorylation. Now if we take a look here, we're looking at this in relation to one cycle of beta oxidation. We're looking at Krebs cycle and oxidative phosphorylation. Our starting materials here, we're starting with our fatty acid. Remember, we have to have fatty acid activation, which is a one-time expense of 2 ATP. So here this would actually be minus 2. We'd say that we would have the generation of 1 FADH2 and 1 NADH, because that happens for every cycle we make one of each. And then we would have the creation of 1 Acetyl CoA since we're only going through one cycle of beta oxidation. Now for Krebs cycle here, we have that 1 acetyl CoA, and we would say that we would have the generation of 1 ATP, 1 FADH2, and 3 NADH. Remember, normally when we do glucose, we have the formation of 2 acetyl CoA's, so these numbers will be double. But here, since we're only dealing with one Acetyl CoA, we only have half of each of these amounts. We would have our end molecule as oxaloacetate. Now here, moving on towards oxidative phosphorylation, we have the dropping off electrons by NADH and FADH2. So we wouldn't generate any of them. We would have the reduction of oxygen into water as our end molecule, but how much ATP would be involved? Well, we can see that we have a total of 2 NADH's. 1 from beta oxidation and one from Krebs cycle. And we have 4 NADH's. Remember that NADH is 2.5 ATP, so times 4 would give me 10. And then we'd have 2 FADH2's, each one is 1.5 ATP, so that's 3 ATP, for a total of 13 ATP molecules. Now adding everything across the board, we'd have minus 2, plus 1, plus 13, that'd give us a total of 12 ATP. And then we'd have 1 plus 1 is 2, and 1 plus 3 is 4. Remember, when we talk about Krebs cycle and oxidative phosphorylation, these are termed our common metabolic pathways. Alright. So this was the total that we would get for each one of these in terms of ATP, FADH2, and NADH. So keep this in mind when we take a look at the total energy involved with fatty acids.
Total Energy from Fatty Acids - Online Tutor, Practice Problems & Exam Prep
Total Energy from Fatty Acids Concept 1
Video transcript
Total Energy from Fatty Acids Example 1
Video transcript
Here in this example question, it says, calculate the total ATP yield from the complete beta oxidation of myristic acid. Here, this represents a 14 Carbon Atom Fatty Acid. So here, the way we start is we're going to say step 1, we have to calculate the number of cycles of beta oxidation. Now remember, your number of cycles is number of carbons of the fatty acid divided by 2, minus 1. So, here we have a 14 carbon fatty acid divided by 2 minus 1, so that'd be 7 minus 1, so we'd have 6 cycles.
Next, we're going to calculate the total number of NADH and FADH2 produced during beta oxidation. This is equal to the number of cycles. Because we have 6 cycles that means we're going to have 6 NADH's and 6 FADH2s.
Next, we have to calculate the total ATP, NADH, and FADH2 produced during the Citric Acid Cycle. Now, here this depends on the number of Acetyl CoA molecules from beta oxidation. Remember the number of Acetyl CoA is equal to the number of carbons of your fatty acid divided by 2. So, it'll be 14 divided by 2, so that means we'd have 7 Acetyl CoAs. So, here, we have 7 Acetyl CoAs. We would say that would be 7 times 1 for 7 ATP. We'd have 7 times 3 which gives me 21 NADH's. And then, we would say here, 7 times 1, which would give me 7 FADH2s. Remember, this number of 3 and 1 for NADH and FADH2, we talked about that in the very beginning when it came to the amount of total energy evolved from a fatty acid oxidation. If you don't see that, go back to the previous video to see those values.
Now, here we have to convert our total number of NADH and FADH2 to ATP from Oxidative Phosphorylation. Now remember, 1 NADH is equal to 2.5 ATP. 1 FADH2 is equal to 1.5 ATP. So based on our numbers here, what are we going to do? We're going to say here that we got, 21 NADH's here from the citric acid cycle. And then, also remember we have another 6 NADH's here based on the number of cycles when it comes to beta oxidation. So we'd have 6 + 21 which gives me 27 NADH's. We multiply that by 2.5 ATP which would give me 67.5 ATP total based on NADH. Now, here we have 7 FADH2's from the Citric Acid Cycle and then another 6 that we got from Beta Oxidation based on the number of cycles. So that'd be 6 plus the 7, so that'd give me 13 FADH2. Remember each one is 1.5 ATP, so that give me 19.5 ATP.
Then we're going to say, add all the ATP's and remember there is a one-time expense of 2 ATP involved. So here we'd add up the 67.5 ATP plus the 19.5 ATP minus the one-time cost of 2 ATP, that would give me 85 ATP total. So 85 would be the total amount of our ATP yield when we're talking about the complete beta oxidation of this 14 Carbon Atom Fatty Acid.
Rank the following molecules based on amount of energy stored in them in increasing order (per mol).
I. Sucrose II. Arachidic III. Glucose IV. Behenic (22:0)
I, III, II, IV
III, I, II, IV
II, IV, III, I
IV, II, I, III
Provide total moles of ATP produced by complete β-oxidation of 3.4 g of palmitic acid (256.43 g/mol).
1.4 ATP
31.2 ATP
106 ATP
1.43 ATP