Early estimates suggested that the oxidation of glucose via aerobic respiration would produce 38 ATP. Based on what you know of the theoretical yields of ATP from cellular respiration, show how this total was determined. Why do biologists now think this amount of ATP per molecule of glucose is not achieved in cells?

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Welcome back everyone. Here's our next question. How much net A. T. P is produced when one glucose is completely oxidized via aerobic respiration well to help us keep track of all the A. T. P production going on. And it's two different processes and where it's coming from and how much I have sort of this handy little diagram I'll put up here. So let's look for our steps and see how much A. T. P. Is being generated. So the first part of the process is obviously the glycol icis process when you've got glucose being converted to piru bait. Um one very important thing to note here, we have 2 80 P molecules that have to be used up as part of this process. We cannot forget to take into those into account because our question says how much net A. T. P. Is produced. So don't lose track of those 2 80 P. Being used up. So let's look at which how much is being generated again. Two ways of generating a teepee in respiration. You've got the direct route substrate level phosphor relation. And that's indicated by this just straight line right here. And that's when you just have the direct transfer a phosphate group from another molecule onto a molecule of ADP. And you make a teepee. So that's kind of the direct route from the glycol is this process. We make 4 80 P molecules that way. Then you've got the indirect route of oxidative phosphor elation. When our respiration process generates electron carrier molecules. They bring electrons to the electron transport chain, electrons travel down that chain as they release their energy it pumps protons across the membrane against that gradient. And then through the process of keamy osmosis. As those proteins diffuse back over the membrane, the energy released as they move down their concentration gradient is used to produce molecules of A. T. P. So glycol Asus produces two molecules of N. A. D. H. And A. D. H. Is one of those electron carriers. However, we do have to note this process takes place in the site is all. And unlike the N A. D. H, we'll see a little later on in the mitochondrial matrix, N A. D. H from the side is all drops its electrons off a little lower on the electron transport chain. As we recall at the beginning of the chain, the electrons are very high energy. They release a bit of energy each time they move to a new complex in the chain. Uh so this N A. D. H, leaving its electrons a little further along on that chain, they generate less energy in the end. So for each molecule of N A. D. H. From the side is all, we generate two molecules of a teepee. So these two and a Dhs on the side is all make four molecules of a teepee. Then after like colossus piru bait is converted to acetyl coa A. That reaction generates two N A. D. H molecules were now in the matrix. So in the matrix these electrons are dropped off at the highest energy level of the electron transport chain. So in that case each N A. D H molecule um its electrons will generate enough energy moving down that train to produce six units of a teepee. Through keamy osmosis. Or each one will generate three. So the two and a th molecules will generate six total. Now let's keep moving the seal. Coetzee enters the Krebs cycle. The Krebs cycle produces 2 80 ps by substrate level phosphor relation are direct route. It generates six matrix and A D. H molecules. So each one makes leads the production of 3 80 P. S. So we've got 18 more 80 p coming from that. And finally it generates two molecules of F A. D. H two. This is another electron carrier. But like besides all again and th it leaves its electrons a little further down the chain. So each molecule of an F A D H two just generates two molecules of A T. P. So the two molecules of F A. T. H. To make four molecules of ATP. So now to get the net a Tp production, we're just going to add it all up. So when we add all this ATP produced we're gonna get 38 molecules of a teepee being produced. But do not forget our two molecules that got used up. So from like Alexis we have negative to a T. P being produced. So when we add this all together, we're getting a nut A. T. P. Production of 36 80 P molecules. So let's look over at our answer choices. We see that choice c. 36 80 p. So how much net A. T. P. Is produced, with one molecule of glucose being completely oxidized by aerobic respiration. That's choice C. 36 80 p.

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Key Concepts

Aerobic Respiration

ATP Yield Calculation

Realistic ATP Production