What happens to the carbon atoms in sugar catabolized by Esche...

Question

What happens to the carbon atoms in sugar catabolized by Escherichia coli?

Accepted Answer

Hi, everybody. And welcome back. Our next question is in the process of cellular respiration in a muscle cell. What is the fate of carbon atoms in a molecule of glucose? A? They are all converted into A TP molecules B, they're all incorporated into DNA molecules C, they are released as CO2 and H2O or D they form lactic acid only. So we're talking about cellular respiration starting with glucose. And so let's think about those pathways. We start with glucose, which has six carbons. Of course, we're talking about the fate of the carbon atoms. Glucose during glycolysis gets converted into two pyruvate molecules, each of which have three carbons. So we still have, we're tracking all of our carbons here. So that's in glycolysis. And then we have that process of pyruvate oxidation which will give us two acetyl coa molecules, but a Castille Coa only has two carbons. So that also produces two molecules of carbon dioxide. So there's two of our carbons, sorry about that, started to run off the screen, had to scoot it over. And then we recall that this acetyl coa enters the citric acid cycle. Where are the rest of this or I should say the rest of these carbons get fully oxidized into separate molecules of carbon dioxide. So we end up producing four molecules of carbon dioxide as a result. And then we also produce N A DH and FA DH two. And we should add N A DH up at our pyro oxidation as we convert these carbons into carbon dioxide. As we said, we're oxidizing them. So they're giving away electrons. What happens to those electrons? Well, they get transferred to these electron carriers. N AD plus and F ad, they've now been reduced to N A DH and fa DH two. And then those electron carriers will bring those electrons over to the electron transport chain. They will go through oxidative phosphorylation, which is going to produce ATP and water. Let's put electrons on this arrow here going from our electron carriers to oxidative phosphorylation. So why do I bring it all the way through there? Because our answer choice, we know that the carbons are being converted to carbon dioxide. We have this answer to C they were released as CO2 and H2O. So that's a little bit confusing. The carbons aren't becoming water. But don't forget our carbons are being oxidized. Some of some electrons are being released. Those electrons go on into oxidative phosphorylation are transferred ultimately to oxygen and water is produced. Let's look at our other answer. Choices to understand why they are not correct choice. A they're all converted into A TP molecules. Well, our carbons are not converted into A TP. They, the A TP is produced as the carbons are released as carbon dioxide electrons are released. The A TP comes from that oxidated phosphorylation. Mainly there's of course, a little bit of A TP released earlier in glycolysis so that those A TP molecules are produced to store the energy released by the metabolism of glucose. But that's not where the carbon atoms are going. So that's why that's not our answer. Choice. Choice. B they're all incorporated into DNA molecules. Well, this is not happening in cellular respiration. There is the pentose phosphate pathway in which some of the carbons from glucose are used. It's an alternative branching off from glyco glycolysis and it leads to the production of the precursor sugar to DNA and RN A as well as producing some N ad ph with the electrons released um from that glucose. But again, in the pentose phosphate pathway, some of the carbons are incorporated into the sugar precursor that will be used for the synthesis of DNA molecules. Um but not, this is not happening in cellular respiration. So that's why Tri B is not our answer. And in choice D they form lactic acid only. Well, we can have carbon atoms from glucose incorporated as lactic acid. But this is in the pathway of anaerobic fermentation, not cellular respiration. So that's the alternative pathway that doesn't produce nearly as much A TP. But switch to when there's not any oxygen left in those muscle cells. So choice d not our correct answer. So once again, in the process of cellular respiration in a muscle cell, what is the fate of carbon atoms in a molecule? Glucose? Choice C they are released as carbon dioxide and water. See you in the next video.

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What happens to the carbon atoms in sugar catabolized by Escherichia coli?

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