What is the purpose of the Cori cycle?

Question

Accepted Answer

Hello everybody. Our next question says which of the statements about the coy cycle is or are correct? And we have four statements numbered one through four and then four answer choices, A one only B one and two C three only or D two and three. So one thing to notice in interest of time if we were on a test is that statement four is not going to be correct. None of our answer choices have statement four in that. So we don't need to even evaluate that statement as we know, it can't be a correct one. We will look through it ourselves because this is a practice problem and we'll be thorough. But on a test, that's just a way of being a little speedier. But again, important to note, we have the possibility that we have more than one correct statement here though only either one or two, correct. So again, interest of test taking strategy. So let's recall kind of that basic outline of the quarry cycle and then evaluate these statements. We recall that the quarry cycle is that process that prevents a build up of excess lactic acid in the body. And we think of an organ that might protect us from something that could be harmful to us. That reminds us that the coy cycle takes place in the liver. So what would cause a situation where we'd have a build up of excess lactic acid. Well, when we have cells going through lactic acid fermentation. So a situation where we have anaerobic conditions. So we have a muscle, undergoing intense exercise. So those muscle cells have run low on oxygen from the constant activity they've been going through, they can no longer produce all the A TP that's possible through cellular respiration. But they can produce a little bit of a TP through lactic acid fermentation. But of course, lactic acid fermentation results in the final product of lactate. And if too much lactate, too much lactic acid builds up in the body that can cause lactic acid lactic acidosis. So when this lactate is being produced, it can be transported to the liver where it can be converted into pyruvate and then to glucose by gluconeogenesis. So with that in mind, let's evaluate our statements here. In statement. Number one, it says during the quarry cycle, lactate produced by anaerobic respiration is directly converted into a TP in the liver. Well, what's the problem here? The lactate is not converted into a TP. Instead it is converted into pyruvate and then to glucose. So I'll say, converted into glucose in the liver. And this process does not produce a TP as we can logically think through glucose is being synthesized as a more complex larger molecule. So this requires an input of a TP for this process. So statement one incorrect, which rules out choice A one only and B one and two. Now let's look at statement number two two says the quy cycle only occurs during periods of high oxygen availability when aerobic respiration is at its peak. Well, this one's pretty easy to rule out because we wouldn't need the Quy cycle if we have high oxygen availability. Because no excess lactate is being, being uh built up. It's not being produced because we don't have anaerobic respiration taking place. So it only occurs during periods of low oxygen availability when anaerobic respiration is taking place. Well, now, at this point, we only have one possible correct answer left which is statement three and on a test, I wouldn't even evaluate this. I would know that because two is incorrect. Choice D two and three can be ruled out. And by elimination, my answer is choice three. Choice C three only. But again, because this is a practice problem, you can stop now or we can go through the other two statements just in interest of being thorough. So step three, our correct one says the quarry cycle converts lactate from muscles into glucose in the liver requiring additional A TP to maintain glucose homeostasis during anaerobic conditions. So yes, that is our correct description. And finally choice four, which we know must be incorrect lactate generated during intense exercise is rapidly transformed into pyruvate by the liver which subsequently aids in the production of a TP for muscles. So it is not pyruvate though it is transformed into pyruvate, but then also enters gluconeogenesis and produces glucose. And it's that glucose which could then through glycolysis aid in the production of a TP not pyruvate. So once again, our correct answer here, our only correct statement about the core recycle is choice C statement three. Only see you in the next video.

What is the purpose of the Cori cycle?

Key Concepts

Cori Cycle

Lactate Production

Gluconeogenesis

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