Gluconeogenesis - Video Tutorials & Practice Problems
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Gluconeogenesis Concept 1
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Now, we can say that gluconeogenesis is a sequence of 11 biochemical reactions with two pyros as are starting metabolites. And we're gonna say here that reactions 129 and 11 are different from glycolysis with the rest being the same. If we take a look here on top, we have Gluco genesis and with Gluco genesis, our goal is to go from pyruvate to glucose and for glycolysis on the bottom, here we start with glucose and our goal is to get to pyruvate. So they're going in opposite directions. They are similar in many parts. But again, it's reactions 129 and 11 that are different. If we go back up to um Gluco Genesis, we have pyruvate reaction. One will transform that into oxy acetate. Going into reaction two, we make pep which is phosphoenolpyruvate. And then we're gonna have a reversible reaction re um 3 to 8 which transforms it into fructose, 16 bisphosphate reaction nine changes that into just fructose, six phosphate and then reaction 10 which is reversible, gives us glucose six phosphate. So that 11, we finally get glucose like col as we go the opposite way, we're starting out with glucose. Step one, gives us glucose six phosphate. Step two is reversible, gives us fructose six phosphate. Step three, here would change that into fructose, 16 bisphosphate. And then steps 4 to 9 are reversible. We can go from fructose, 16 bisphosphate to pep again. And then step 10, go, go straight into pyruvate. We'll go deeper into looking at gluconeogenesis. But just remember, it's a total of 11 biochemical steps or reactions. And we're gonna say here it's reactions 129 and 11 that are different from glycolysis with the rest being the same.
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Gluconeogenesis Concept 2
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Now reaction, one of gluconeogenesis deals with oxy acetate formation. We mean we're dealing with two pyruvate. So this happens twice in it. We have carbon dioxide is added to pyruvate by pyruvate carboxylate. So remember we're adding coo group, carbon carbon dioxide. And because of this, we have to use a carboxylate enzyme and this is gonna produce oxalacetate in this. A TP is converted to AD P. So energy is invested into this. And what we need to note here is that amino acids he entered either as pyruvate or oxy A here. If we take a look, we have our pyruvate here, we're gonna use, we're gonna add our carbon dioxide. We utilize A TP in the process. A TP is converted into AD P. We use like we utilize our enzyme pyruvic carboxylase and we add coo negative in order to create OXY A. So this represents reaction one of gluco genesis.
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concept
Gluconeogenesis Concept 3
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Now, in reaction to we have our two oxy acetates. In this step, we have decarboxylate, which means that we're gonna lose carbon dioxide and we have phosphorylation which means we're gonna add an inorganic phosphate group. Here we're gonna use PEP, we're gonna say carboxy kinase. Remember a a kinase is the class of enzymes we use for the transferring of a phosphate group to our specified molecule or the removal of a phosphate group in some instances. Now, here it's gonna remove CO2 in order to add our inorganic phosphate group. In this reaction, we have GTP is converted to GDP and one carbon atom is lost as carbon dioxide. So here we have our oxy acetate. We're utilizing our GTP, which loses the inorganic phosphate group to become GDP in the process, we're losing carbon dioxide. So that's the decarboxylate step. The enzyme that we utilized here is fossil pol pyruvate, which is PEP and then carboxy kinase. Here we include our phosphate group as po three to minus. So that's how we go from oxy aide to fossil pheno pyruvate or Pep
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example
Gluconeogenesis Example 1
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In this example, it says how many total carbon atoms are lost in the first two reactions of gluconeogenesis. Now remember in reaction one, we're dealing with a carboxyl reaction or adding a carbon dioxide molecule in reaction two, we have decarboxylate that occurs as well as phosphorylation. But we're focusing on the carbon atom. We have decarboxylate where we lose a carbon dioxide. So what is the net change? We added one in reaction one, we lost one in reaction two. So overall they kind of it's a wash. So we're gonna say a total of zero net carbons are lost in the process, right? So here the answer will be option. A
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Gluconeogenesis Concept 4
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In reaction three of gluconeogenesis, we have hydration. Again, we have two molecules or two metabolites involved. So this happens twice. Here we have pep undergoes hydration to produce two PG which is two phospho glycerine. Now here, in order to do this, it's catalyzed by the enzyme enolase. Enolase is just a class of Li Aes. And remember the way li Aes work is they catalyze reactions in which things are added to double bonds or pi bonds. If we take a look here, we have pep which is phospho eop Iru, we have the presence of a pi bond because of the presence of that double bond. We're gonna say here through the use of our enolase, water comes in and hydration just means the addition of water in this, we have water which is basically um H plus omooh minus the H adds to the carbon that possesses the inorganic phosphate. And then the oh will attach to this ch two on the bottom. And by doing this, we create two phosphor glycate as our product for reaction three of gluconeogenesis. So just remember we're undergoing hydration in order to do this, we use a class A specific class of lias is called the Enola enzyme, right. So we're going to add water to our pop our pi bond, thereby breaking it and creating an alcohol as our product.
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Gluconeogenesis Concept 5
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In reaction four of gluconeogenesis, we're starting out with two PGS and two PG is two phospho glycerine. And we're gonna say here that our two PG molecules they're gonna undergo isomerization and they're going to yield three pg or three phospho glycerine. And we're gonna say here this is catalyzed by our enzyme fossil glycate mutates muta belongs to the class of enzymes called our isomerase. So basically these two structures, they have the same molecular formula but different connections. They are isomers of one another. If we take a look here, we have two phospho glycate, the inorganic phosphate is on carbon number two of our structure through the utilization of our phospho glycerated muta, we can have it migrate to position three of this chain. And in that way, we go from two phospho glycerated to three phospho glycerated. So here, basically this oh now is located here in the inorganic phosphate itself, moved to position three. And that's how we're able to go between these two different types of glycerated molecules
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Gluconeogenesis Concept 6
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Reaction. Five of gluconeogenesis involves a phosphate transfer. Remember a class of enzymes that we utilize when it comes to the transferring of a phosphate group are the kinesis. Now, here we're going to say that three PG which is three phospho glycate produces 13 bis phospho glycate by adding or gaining an inorganic phosphate group. Here, we're going to say that it's catalyzed by our phospho glycate. Again, kinase kinase is the class of enzymes we use for phosphate transfers. Now what happens here is that we have a TP and it's converted to AD P. If we take a look at our reaction, we have our three phospho glycate or three PG. The energetic phosphate is on carbon three, we're going to say our phospho glycate Kase. It's going to remove an inorganic phosphate group from a TP, transforming it into AD P. What's going to happen here is that this oxygen here that's on carbon. Number one will gain an inorganic phosphate doing this creates 13 bis phosphate phospho glycate as our new product. So just remember when it comes to reaction five of gluco genesis, it is a phosphate transfer. The class of enzyme we use to transfer phosphate groups from one molecule to a new specified molecule. Is a kinase.
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Gluconeogenesis Concept 7
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Now reaction six of gluconeogenesis is a reduction. Here. We're going to say that 13 bis phospho glycerine undergoes reduction to produce G three P which is glyceraldehyde three phosphate. Now we're gonna say it's catalyzed by the enzyme glycol glyceraldehyde three phosphate or G three P dehydrogenase. Remember our dehydrogenase are enzymes of choice when dealing with redox reactions. We're dealing with the reduction here. So we can utilize it. Now, here we're gonna say in this process where we have reduction under being undergone, we're gonna say N A DH is oxidized to N ad positive. If we take a look here, we have our 13 bis phospho glycate. We have our two inorganic phosphates, one on carbon two on one and one on carbon three. We're gonna say N A DH is oxidized to produce N ad positive. Here, we're also going to have an inorganic phosphate group and through the use of dehydrogenase, this phosphate group that is lost is replaced by a hydrogen. So we just created a carbon hydrogen bond by removing a carbon oxygen bond. This is where reduction occurs. Remember, reduction is either the loss of oxygen or the gaining of hydrogen. So here we can see that carbon loss in oxygen and it also gained a hydrogen which represents a reduction reaction.
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concept
Gluconeogenesis Concept 8
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Now reaction seven of gluconeogenesis deals with isomerization in it. We have our G three P molecules which is glyceraldehyde three phosphate. They are isomerize to DH A P which is dihydroxy acetone phosphate. Now, here, this is catalyzed by the enzyme tri tral phosphate isomerase because this is an I isomerization reaction. Now note we're gonna say glycerol enters gluconeogenesis. As DH A P remember that our non carbohydrates tend to go from their non-carbohydrate forms. We talking about amino acids or lactate. They go into the pyruvate and then they can go to DH A P and eventually they can go to pyruvate. I'm to glucose when it comes to Glycerol. Glycerol bypasses this and it goes from Glycerol straight to DH A P to eventually becoming glucose, right. So if we take a look here, we have Glycerol high three phosphate or G three P. We have our inorganic phosphate on carbon three position three. We're utilizing our Isama enzyme here, which is a reversible reaction. Here. We get to DH A P, which is our dihydroxy acetone phosphate. And remember our Glycerol, which is our three carbons with 30 groups. It goes straight from this form into DH A P to eventually become glucose. Right. So step seven or reaction seven of gluconeogenesis is a summarization reaction.
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Gluconeogenesis Concept 9
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Now reaction eight of gluconeogenesis is a linkage reaction. Here are enzyme, all delays combined, two trials phosphates into fructose, 16 bisphosphate. Here, we're gonna have our DH A P which is dihydroxy acetone phosphate. And it's going to combine with glyceraldehyde three phosphate through the use of our Aase enzyme we get at the end our fructose 16 bisphosphate. So again, think of this as the opposite type of reaction from glycolysis where we would have split fructose 16 bisphosphate into DH A P and G three P. Right. So here, now we're combine them together through the use of an enzyme of all the lace.
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example
Gluconeogenesis Example 2
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Here in this example, question, it says which enzymes so far are involved in glycolysis but not gluconeogenesis. So at this point, we've gone over reactions 1 to 8. If we take a look at the first one, it says pyruvate carboxylase. Now this is the enzyme of choice that we use for reaction one in which we're going from pyruvate to oxalacetate. So this has been talked about has been involved in glycolysis and also gluconeogenesis. Next, we have phospho glycate kinase. Now here this is reaction five of gluconeogenesis. And remember we're looking to see what's not part of gluconeogenesis in reaction five. This involves a phosphate transfer because we're using the class of enzymes known as a kinase. Now, cnd now D is actually reaction six, we're gonna say that it follows what we do in reaction five. In this one, it's a reduction reaction because we're using glyceraldehyde three phosphate dehydrogenase. Remember this is involved in redox reactions. In this case, in terms of a reduction reaction. The answer here would have to be option C, this one is involved in glycolysis, but at this point hasn't been involved in gluconeogenesis. So option C would be our final answer.
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Gluconeogenesis Concept 10
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Now, in reaction nine of gluconeogenesis, we have dephosphorylation which means we're gonna remove an inorganic phosphate. Here. The enzyme that we use is fructose, 16 bis phosphatase. A phosphatase is just a class of enzyme that's responsible for removing inorganic phosphate from a specified molecule. Now, here it removes the inorganic phosphate to form fructose six phosphate. If we take a look here, we have our fructose, 16 bisphosphate, we have our two phosphate groups. Here, we're going to lose one of these inorganic phosphates through the use of the enzyme fructose, 16 bisphosphate. Here we keep intact this inorganic phosphate group but the other one is lost. And now we have C H2O H. Here. In that way, we've just created fructose six phosphate as our new product reaction. Nine of gluconeogenesis.
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example
Gluconeogenesis Example 3
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In this example, it says, why is it not possible to de phosphor fructose 16 bisphosphate with phosphofructokinase enzyme. All right. So here, phosphofructokinase enzyme does not function properly in the cytoplasm of the cell. That's not true. It can fossil fructokinase catalyzes transfer of a inorganic phosphate group from one molecule to another. Not a removal of an inorganic phosphate group. That is true. Remember your class of enzymes known as the kinas help with phosphate transfers. We're taking our inorganic phosphate and moving it to another specified molecule here. That's not what's going on here. We're trying to completely remove the inorganic phosphate. We're not transferring it to somewhere else. So this is the answer. If we look at the other options, phosphor fructokinase lacks enough energy to catalyze dephosphorylation. So that's not true. It just transfers the phosphate group. It doesn't completely remove the phosphate group without transferring. And then here we're going to say no. In this case, we're trying to do defrost correlation to create fructose six phosphate. We're not transferring the phosphate group somewhere else. We're just completely removing it. So this wouldn't answer the question correctly. So here our answer would have to be option B.
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Gluconeogenesis Concept 11
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In this video, we're gonna take a look at reactions 10 and 11 of gluconeogenesis. Now, in reaction 10, we have isomerization here. Our enzyme is phospho gluco isomerase which isomerize fructose six phosphate into glucose six phosphate. Remember, these have the same molecular formula, they have different connections. So they're isomers of one another which is why we would use an isomerase as our class of enzymes. So here we're going from fructose six phosphate to glucose six phosphate utilizing this isomerase. Now, here we're gonna say the final reaction reaction 11 is a def phosph correlation. Here we're removing an inorganic phosphate. We're gonna say the enzyme glucose six phosphatase removes a inorganic phosphate group forming glucose. Now, the responsibility of a phosphatase enzyme is the removal of an inorganic phosphate from a specified molecule. This is different from a kinase. A kinase deals with a phosphate transfer. We're removing a inorganic phosphate from one molecule and handing it over to another. That's what that's not what's occurring. Here. We're just completely removing the inorganic phosphate. So here we're gonna have our in organic phosphate. We use our phosphate taste to remove it completely. So now this becomes C H2O H to help us form glucose as our final molecule within gluco neogenesis.
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example
Gluconeogenesis Example 4
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Here in this example, question, it says steps nine and 10 of gluconeogenesis. Now remember steps nine and 10 or reactions nine and 10 deal with dephosphorylation or removing an inorganic phosphate group. This is accomplished with the use of a phosphatase enzyme. Remember this is different from a kinase. Achin deals with a phosphate transfer. In these instances, we typically use AD P or A TP more um removing or transferring of these inorganic phosphate groups phosphatase. They're just completely removing the inorganic phosphate group without transferring it to another molecule. So here uses AD P to dephosphorylation and produces a TP. Here, if we're talking about this situation, we're talking about a kinase, not a phosphatase. So this is not true, produces a eight AD P as a result of the phosphorylation. No, we're not transferring an inorganic phosphate. We're not trying to take an inorganic phosphate from A TP and transferring it over to create AD P as a consequence requires GTP to de phosphate. So same kind of idea GDP A TP. The answer is D does not require energy to de phosphate. Again, we're using a phosphatase enzyme. Its responsibility is just to remove the inorganic phosphate altogether. And this does not require the use of energy.
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Gluconeogenesis Concept 12
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Hey, everyone. So in this video, we're gonna talk about our three memory tools to help us remember gluconeogenesis. These memory tools will help us to remember the reactions involved our metabolites as well as our enzymes. If we take a look at memory tool, number one, we're going to say this deals with our reactions and it is in the first two minutes of an accident, we have to call 911. Now remember when it comes to gluconeogenesis versus glycolysis. Glucon genesis is different at reactions 129 and 11 from glycolysis with the rest being the same. Next we have memory to two which deals with our metabolites. In this one, we say that pirates only pop fruit from gorgeous gardens. Now here, what does this mean? Well, here pirates stands for our beginning metabolite of gluconeogenesis which is pyruvate. O deals with oxy acetate P is for pep fruit. F here stands for fructose, 16 bisphosphate F from, from stands for fructose, six phosphate. Gorgeous. Here is glucose, six phosphate and gardens. What's the last time we want from Gluco neogenesis? That's right. Glucose. So here gardens. G here stands for glucose. Next we have our enzymes for memory tool three. And here we say that pirates consume Pepsi K and we're gonna say fructose biz fizz and then we're gonna say glucose fizz. All right. So what does this mean? Well, here when we say pirates consume, we're talking about pyruvate carboxylase. This is what allows us to go from pyruvate Toyo. Ay. Next we say pep CK. Well, this is pep carboxy kinase. This will allow us to go from our oxy acetate to just our fructose 16 bisphosphate. Next, we have fructose biz fizz. This is fructose 16 biz phosphatase. Remember a phosphatase is an enzyme whose role is just to completely remove our inorganic phosphate group. And then finally, we have glucose pz this would be glucose six phosphatase. Again, it's there just to remove an entire inorganic phosphate group. In this case, we're removing an inorganic phosphate group from glucose six phosphate. In order to create glucose. Again, remember gluco genesis, we're trying to create glucose that will be our end metabolite. And we're utilizing this last enzyme in order to do that. So just remember, rely on these three memory tools help you get a full understanding of gluconeogenesis where we first look at the different reactions involved that are different between gluconeogenesis and glycolysis. Next, looking at the metabolites, as you go from one to the next to our eventual destination of the formation of glucose and then are enzymes involved the enzymes needed to go change one metabolite to another. So we get ultimately to glucose once again. All right. So just keep this in mind when looking at Leonia Genesis.
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concept
Gluconeogenesis Concept 13
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Now here, when we take a look of a summary of gluconeogenesis, we're gonna say gluconeogenesis reduces pyruvate to glucose via the following reaction. And it is we have two pyruvate molecules. We're gonna use four A TP, two GTP plus two N A DH. And at the end we get glucose. Our fourth memory tool here is reaction one which deals with a TP. Reaction two which deals with GTP and reaction five, which deals with A TP yet again and it is all the pirates. So reaction one A TP reaction to GTP got to party to reaction to and then reaction five deals with a TP again at 5 p.m. So reaction 5:05 p.m. right? So this gives us a summary of what the overall reaction of gluconeogenesis is. And memory tool four helps us to remember which reactions involve A TP and GTP respectively.
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example
Gluconeogenesis Example 5
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Here in this example, question it says reactions one and two consume blank and blank and are catalyzed by which enzymes. All right. So remember memory to four, we're gonna say here that for reaction one, it's a TP because remember we're gonna say here all the pirates. So A TP. So that means the answer is gonna be either A or B reaction to is GTP. All the pirates go to party. So GTP. So it's still either A or B. Now in reaction one, we have oxy acetate formation. Remember that's us going from pyruvate to oxy acetate. In order to do this, we need to add a carbon dioxide to pyruvate. And we'd say that if we're bringing in a carbon dioxide, that's gonna require a carboxylase. So here part of a carboxylase. And then for reaction two, we have a decarboxylate as well as a phosphorylation. Here, we're going to have to lose a carbon dioxide from oxy acetate and bring in an inorganic phosphate. Since we are basically transferring an inorganic phosphate from GTP to create our new structure, which is pep, we'd have to use a kinase enzyme. And here it would be a carboxy kinase because we have co tub being removed to usher in the inorganic phosphate group. So here, the answer would be B here, it would be py pyruvate carboxylase and then basically fossil uh phosphoenolpyruvate is pep and it'd be carboxy kinase. So here, our answer would have to be option B.
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Problem
Problem
The following metabolites are present both in glycolysis and gluconeogenesis, except:
A
oxaloacetate
B
fructose-1,6-bisphosphate
C
glyceraldehyde-3-phosphate
D
dihydroxyacetone phosphate
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Problem
Problem
Which molecule is added to pyruvate and then removed in the next reaction?
A
H+
B
H2O
C
PO32-
D
CO2
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Problem
Problem
Enzyme responsible for decarboxylation and phosphate transfer in the same gluconeogenic reaction is:
A
Tyrosine kinase
B
Oxaloacetate carboxykinase
C
Pyruvate kinase
D
Phosphoenolpyruvate carboxykinase
E
Phosphofructokinase
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Problem
Problem
Fructose-1,6-bisphosphate is dephosphorylated by ________________ to fructose-6-phosphate.
A
Glucose-6-phophatase
B
Fructose-1,6-bisphosphatase
C
Phosphofructokinase
D
Fructose-6-phosphotase
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concept
Cori Cycle Concept 14
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Now, the coy cycle represents a cyclic metabolic pathway that transports lactate from muscle cells to liver cells and converts it to glucose. Now, recall that lactate is produced by muscles, muscle cells during anaerobic conditions and it is then transported by bloodstream to liver cells and converted to glucose through gluconeogenesis. Now, if we take a look here, we have our muscle cell here and we have our liver here. What happens is we're going to have the transporting of lactate from the muscle cells towards our liver. The lactate is then converted into pyruvate and through the incorporation of energy in the form of A TP, we can transform that into glucose being a result of gluco neogenesis. This glucose can then be shuttled off towards our muscles or can be used. And here we have um glycolysis taking place which converts our glucose into pyruvate. Here, we would have some of the releasing of a TP. Remember in phase B of glycolysis, this is the energy forming phase of glycolysis. So A TP would be given off and then remember in conditions of anaerobic conditions, we'd have fermentation going on where pyruvate wouldn't be able to go into stages three and four of food metabolism and instead would do fermentation, this would in turn create lactate and start the cycle cycle all over again. So basically what this is doing is it's taking something like lactate and converting into something useful in the form of glucose which our muscles can then use for energy. Right. So this is the beauty of the Hoy cycle, which again is a cyclic metabolic pathway.
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example
Cori Cycle Example 6
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In this example, question, it says the primary purpose for Quy cycle is to all right, produce lactate through fermentation process. Lactate is something we don't really wanna build up within our muscle cells. Ok. So here this would make sense as a primary purpose for the coy cycle to provide a metabolite for gluconeogenesis. All right. So here the coy cycle, its primary focus, primary reason and and then and function is not to create a metabolite for glucon genesis. Next, we're gonna say generate glucose for muscle cells to use as energy source. This is it we're converting something that is not great for muscle cells in the form of lactate and shoveling it off from the muscle cells to our liver to be converted into glucose through gluconeogenesis that can then be shuttled towards our muscles for energy. It helps to provide an energy source for muscle cells. So this is the answer here, provide liver with much needed energy. Here it's just shuttling over the lactate to the liver cells. The liver itself is helping to convert that lactate into something useful in the form of glucose. So here, the best answer would have to be option C.
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Problem
Problem
Which of the following statement(s) correctly describes the Cori cycle?
A
Lactate is converted back to pyruvate in the muscles.
B
Conversion of lactate to glucose in the liver generates ATP.
C
Glucose from muscle cells is transported to liver through bloodstream.
D
Lactate from the muscle cells is regenerated into glucose in the liver.