Total Energy from Glucose - Online Tutor, Practice Problems & Exam Prep

The complete oxidation of one glucose molecule involves glycolysis, pyruvate oxidation, and the Krebs cycle, yielding a total of 32 ATP. Glycolysis produces 2 ATP and 2 NADH from glucose, while pyruvate oxidation generates 2 NADH and 2 Acetyl CoA. The Krebs cycle, utilizing 2 Acetyl CoA, results in 2 ATP, 6 NADH, and 2 FADH₂, along with 4 CO₂. The electron transport chain and oxidative phosphorylation further enhance ATP production, emphasizing the importance of metabolic pathways in energy yield.

Total Energy From Glucose Concept 1

Hey everyone. So in this video, we're going to talk about the total energy from glucose. Now here we're going to say complete oxidation of 1 glucose molecule produces the following. And here we're looking at the metabolism of 1 glucose molecule through Glycolysis, pyruvate oxidation, and the Krebs Cycle, also known as the Citric Acid Cycle. Now here with glycolysis, remember, there are 10 reactions involved. The premise is that we have 1 glucose molecule that's split in half. Here, it will create 2 pyruvate molecules. We'd also create 2 NADH high-energy molecules, as well as 2 ATP molecules. For pyruvate oxidation, we now have our 2 pyruvate molecules. We'd say that they each would make 1 Acetyl CoA, 2 Acetyl CoAs in total. We'd have 2 NADH molecules being formed and 2 carbon dioxides.

Now finally, we have the Krebs Cycle. With the Krebs cycle, we're also talking about the Citric acid cycle, the same thing. We have our 2 acetyl CoAs, which means we've gone from the cytosol to the mitochondrial matrix. Because of that, for each acetyl CoA, we would make 6 NADHs, 2 FADH2s, 2 ATPs, and 4 carbon dioxides. Remember there are 2 acetyl CoAs, so we go through the Krebs Cycle twice to create this total number of products at the end. Now, this is just talking about stage 3 of our food catabolism. We know beyond stage 3, we're dealing with the ETC and oxidative phosphorylation. This would create even more ATP molecules than we've seen at this point. But for these three portions, glycolysis, pyruvate oxidation, and the Krebs cycle slash the Citric Acid Cycle, these are the totals we get for each one of the products formed.

Total Energy From Glucose Example 1

In this example question, it asks how many ATP and how many NADH molecules are yielded by glycolysis? Now, remember with glycolysis, we have Phase A, which is our energy-consuming phase. There, we have our glucose, and we're going to say in reactions 1 and 3, we consume an ATP molecule. So that means we're going to consume 2 ATP in Phase A. But then, for Phase B, okay, so this is A, and then for Phase B, we're going to say this is the energy-producing stage, and in Phase B, it's reactions 7 plus 10, where we create ATP. Here we're going to create 2 ATP, but remember, we have 2 pyruvate molecules involved here from the 2 glyceraldehyde 3-phosphates. So, we'd multiply this number times 2. So it's 4 ATPs that are being created within Phase B.

But here we're talking about the net. When we're talking about yields, here we're talking about what's the net value of ATP created. We consumed 2 and made 4. So, really, it's 2 ATPs, our net value.

Here, we'd say for NADH molecules, this happens under Phase B as well. It happens in reaction 6. And we're going to say reaction 6, we make 1 NADH molecule, but then we have to remember to multiply it by 2 since we're dealing with 2 glyceraldehyde 3-phosphates. So the net would be 2 NADH molecules. Then, pyruvate oxidation yields what? Well, here we have 2 pyruvates. Each pyruvate creates 1 NADH, and since there are 2 of them, that means overall we yield 2 NADH molecules. Right? So this is what we'd say: Glycolysis yields 2 net ATPs, 2 NADH molecules, and pyruvate oxidation yields 2 NADH molecules. These will be our answers for the following example question.

Total Energy From Glucose Concept 2

So here we're going to say that the total energy yield, from 1 glucose molecule is summarized in the table below. So, here we're dealing with glycolysis, pyruvate oxidation, the Krebs cycle, AKA the citric acid cycle, and then oxidative phosphorylation. Remember, ETC and oxidative phosphorylation are combined in terms of stage 4. Now, here we're going to say, to calculate the total that we have in this box, remember, ATP yield through oxidative phosphorylation. We have 10 NADH molecules, each one contributes on average 2.5 ATP, so that'd be 25. And then we have 2 FADH₂s, each one at 1.5 ATP on average, that's 3. So we'd have 28 ATP molecules theoretically. We've already figured out under the Krebs cycle, we have 4 carbon dioxides, 2 ATPs, 2 FADH₂s, and 6 NADHs. We know here that we have our oxaloacetate as the end molecule within our Krebs Cycle or Citric Acid Cycle. Now let's go to glycolysis. With glycolysis, we'd have no carbon dioxide being formed here. We'd have 2 ATP, net ATP being formed, 0 FADH2, and then a net of 2 NADH's. Our end product here would be 2 pyruvates. Remember, we're slicing glucose in half, so to get to the 2 pyruvates at the end of reaction 10 in glycolysis. With pyruvate oxidation, we have our 2 pyruvates, and we're gonna say here through its oxidation, we're gonna create 2 carbon dioxide, we're gonna create 0 ATP, 0 FADH₂, and then we're gonna create 2 NADH's. Here we're going to say, we end with 2 Acetyl CoA, as you go from the cytosol to the matrix or mitochondrial matrix, because of the presence of oxygen. Now, here Krebs Cycle Acetyl CoA goes to oxaloacetate, and then that gets shuttled over to our ETC and oxidative phosphorylation. If we look at all these totals, we can add them up. We have 6 carbon dioxides here, we have 32 ATP, 2 FADH₂s, and then we'd have here 10 NADHs. So this is how we come up with these theoretical values based on each of these stages all happening from 1 glucose molecule.

Which stage of glucose metabolism produces the majority of ATP?

• A. Citric acid cycle
• B. Digestion
• C. ETC + Oxidative Phosphorylation
• D. Glycolysis

How many total equivalent ATP molecules would be produced from 3 moles of glucose through glycolysis in aerobic environment?

• A. 2 ATP
• B. 6 ATP
• C. 7 ATP
• D. 21 ATP

The total equivalent ATP yield from: 2 pyruvate  → 2 Acetyl CoA + 2 CO₂.

• A. 0 ATP
• B. 2 ATP
• C. 5 ATP
• D. 10 ATP

Here’s what students ask on this topic:

What is the total ATP yield from the complete oxidation of one glucose molecule?

The complete oxidation of one glucose molecule yields a total of 32 ATP. This process involves glycolysis, pyruvate oxidation, the Krebs cycle, and oxidative phosphorylation. Glycolysis produces 2 ATP and 2 NADH. Pyruvate oxidation generates 2 NADH. The Krebs cycle results in 2 ATP, 6 NADH, and 2 FADH₂. Finally, the electron transport chain and oxidative phosphorylation convert the NADH and FADH₂ into additional ATP, leading to the total yield of 32 ATP.

How many ATP are produced during glycolysis?

During glycolysis, a net total of 2 ATP molecules are produced. Glycolysis involves the breakdown of one glucose molecule into two pyruvate molecules, generating 4 ATP in the process. However, 2 ATP are consumed during the initial steps, resulting in a net gain of 2 ATP.

What are the products of the Krebs cycle from one glucose molecule?

From one glucose molecule, the Krebs cycle produces 2 ATP, 6 NADH, 2 FADH₂, and 4 CO₂. This is because one glucose molecule generates 2 Acetyl CoA, and each Acetyl CoA goes through the Krebs cycle, doubling the products.

How many NADH and FADH₂ are produced in the complete oxidation of one glucose molecule?

The complete oxidation of one glucose molecule produces a total of 10 NADH and 2 FADH₂. Glycolysis generates 2 NADH, pyruvate oxidation produces 2 NADH, and the Krebs cycle yields 6 NADH and 2 FADH₂.

What is the role of the electron transport chain in ATP production?

The electron transport chain (ETC) plays a crucial role in ATP production by using the high-energy electrons from NADH and FADH₂ to create a proton gradient across the inner mitochondrial membrane. This gradient drives ATP synthesis through oxidative phosphorylation. Each NADH contributes approximately 2.5 ATP, and each FADH₂ contributes about 1.5 ATP, significantly increasing the total ATP yield from glucose oxidation.