Each of these reactions is involved in one of the four stages of metabolism shown in Figure 21.4. Identify the stage in which each reaction occurs.
c. Conversion of glucose to acetyl-CoA

Question

Each of these reactions is involved in one of the four stages of metabolism shown in Figure 21.4. Identify the stage in which each reaction occurs.

c. Conversion of glucose to acetyl-CoA

Accepted Answer

All right. Hi, everyone. So this question is asking us which of these statements about the four stages of metabolism is correct. So here we have four different answer, choices labeled A through D. And for a question like this, I think it's best to just go through each individual answer, choice, talk about them and eliminate the ones that need to be eliminated. Right. So starting off with option A, it says that oxidative phosphorylation produces Aceto coa directly from glucose. Now, what exactly is oxidative phosphorylation? Well, recall it oxidative phosphorylation or oxo for short is actually stage four in metabolism. And it's the main producer of ATP at least in cells that contain mitochondria. This is because oxidative phosphorylation, if you recall involves a series of reactions in which electrons are being transferred across the mitochondrial membrane to eventually establish a gradient, that's rather a gradient of protons that eventually produces a TP. So the reason why we can eliminate option A is because oxidated phosphorylation doesn't actually involve glucose at all. And for that matter, the formation of aceto coa takes place during stage two of metabolism. Ox falls is stage four. So from there, we can move on to glycolysis or excuse me. Option B because Option B says that during glycolysis, glucose is completely oxidized to carbon dioxide and water. All right. So from here, the question is, what is glycolysis or what is the role of glycolysis in metabolism? Well, first, it's important to recognize that glycolysis doesn't actually completely oxidize glucose. The main product of glycolysis is actually pyruvate. Eventually pyruvate can be converted into acetyl coa. And at that point, acetyl coa is brought into the citric acid cycle to be oxidized to carbon dioxide and water. So the main point here is that option B is incorrect because the oxidation or the full oxidation of glucose doesn't actually take place during glycolysis. Rather it takes place afterwards. From here, option C says that ATP is directly produced during the conversion of pyruvate to Aceto coa in the mitochondria. So for option C, we have to recall the main principle of the reaction being described, right. So in this particular case, we're talking about the conversion of pyruvate to aceto coa. So pyruvate is a three carbon molecule and Acito Coe at least the main part of Aido Koe contains two carpets. So here one carbon has been removed from pyruvate, which means that carbon dioxide is released as a product of this step. Now, in addition to this N ad negative, which is an electron carrier is involved in the reaction and NAH is produced as a result. So here ATP is never actually produced in this step. Rather ATP is synthesized at a later point in metabolism. So option C is not correct either. And that brings us now to option D which says that glycolysis can proceed in the absence of oxygen producing pyruvate and a net gain of A TP. This statement is correct because before when talking about option B in the multiple choice, we specifically mentioned that glycolysis produces pyruvate, which then is involved in other steps of metabolism. So during that process, there are steps in which A TP is consumed. But towards the end of the glycolysis pathway, A TP is also produced, this results in a net gain of A TP because more A TP is produced than it is consumed. So to address the last part of the statement, it is correct, right? Because glycolysis does not actually require oxygen, it can take place in anaerobic conditions. This is unlike something like oxidated phosphorylation, which requires oxygen as a terminal electron acceptor when establishing that proton gradient that produces ATP. So our answer is going to be option D in the multiple choice because that's our correct statement. And so with that being said, thank you so very much for watching and I hope you found this helpful

Each of these reactions is involved in one of the four stages of metabolism shown in Figure 21.4. Identify the stage in which each reaction occurs.
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c. Conversion of glucose to acetyl-CoA

Verified video answer for a similar problem:

Key Concepts

Metabolism

Glycolysis

Acetyl-CoA

Each of these reactions is involved in one of the four stages of metabolism shown in Figure 21.4. Identify the stage in which each reaction occurs.<IMAGE>c. Conversion of glucose to acetyl-CoA