Glycogenolysis - Biochemistry
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Which of the following is an example of a catabolic reaction?
Which of the following is an example of a catabolic reaction?
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A catabolic reaction is defined as a reaction used to break down a large molecule into smaller subunits. Of the following options, glycogenolysis is the only option where a larger molecule (glycogen) is broken down into smaller subunits (individual glucose molecules).
A catabolic reaction is defined as a reaction used to break down a large molecule into smaller subunits. Of the following options, glycogenolysis is the only option where a larger molecule (glycogen) is broken down into smaller subunits (individual glucose molecules).
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Which one of the following can store the largest total amount of Glycogen in the human body?
Which one of the following can store the largest total amount of Glycogen in the human body?
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Glycogen is the storage form of glucose, and is more readily accessible than starches or fats. It is used for short-term supply of glucose and in starvation conditions is used up in a matter of hours. It is mainly stored in the liver and skeletal muscle. Glycogenolysis in the liver results in glucose release into the bloodstream, whereas in the muscle the glucose is immediately used up. The highest demand for the glucose is in the muscle, and that is where most of it is stored.
Glycogen is the storage form of glucose, and is more readily accessible than starches or fats. It is used for short-term supply of glucose and in starvation conditions is used up in a matter of hours. It is mainly stored in the liver and skeletal muscle. Glycogenolysis in the liver results in glucose release into the bloodstream, whereas in the muscle the glucose is immediately used up. The highest demand for the glucose is in the muscle, and that is where most of it is stored.
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What is the term for the end of the a glycogen branch from which glucose residues are removed during degradation?
What is the term for the end of the a glycogen branch from which glucose residues are removed during degradation?
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The non reducing end of a glycogen branch is the end from which glucose units are removed during degradation of glycogen.
The non reducing end of a glycogen branch is the end from which glucose units are removed during degradation of glycogen.
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Which of the following compounds is regenerated in the citric acid cycle?
Which of the following compounds is regenerated in the citric acid cycle?
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Oxaloacetate is the four-carbon molecule that is regenerated by the enzyme malate dehydrogenase in order to continue the cycle to form citrate with acetyl-CoA in the first step of the Krebs cycle. The other answer choices are intermediates of the citric acid cycle, but only oxaloacetate is regenerated, making it a true cycle.
Oxaloacetate is the four-carbon molecule that is regenerated by the enzyme malate dehydrogenase in order to continue the cycle to form citrate with acetyl-CoA in the first step of the Krebs cycle. The other answer choices are intermediates of the citric acid cycle, but only oxaloacetate is regenerated, making it a true cycle.
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Which of the following compounds is regenerated in the citric acid cycle?
Which of the following compounds is regenerated in the citric acid cycle?
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Oxaloacetate is the four-carbon molecule that is regenerated by the enzyme malate dehydrogenase in order to continue the cycle to form citrate with acetyl-CoA in the first step of the Krebs cycle. The other answer choices are intermediates of the citric acid cycle, but only oxaloacetate is regenerated, making it a true cycle.
Oxaloacetate is the four-carbon molecule that is regenerated by the enzyme malate dehydrogenase in order to continue the cycle to form citrate with acetyl-CoA in the first step of the Krebs cycle. The other answer choices are intermediates of the citric acid cycle, but only oxaloacetate is regenerated, making it a true cycle.
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Which of the following enzymes is not required to breakdown glycogen into glucose-6-phosphate molecules for further metabolism?
Which of the following enzymes is not required to breakdown glycogen into glucose-6-phosphate molecules for further metabolism?
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In order to break down glycogen into individual glucose-6-phosphate units, all of the above enzymes are required. Each plays a specific role in one of the following activities: degradation of glycogen initially, remodeling of the glycogen so that it can be acted upon by the enzymes, and conversion of glucose-1-phosphate to glucose 6-phosphate.
In order to break down glycogen into individual glucose-6-phosphate units, all of the above enzymes are required. Each plays a specific role in one of the following activities: degradation of glycogen initially, remodeling of the glycogen so that it can be acted upon by the enzymes, and conversion of glucose-1-phosphate to glucose 6-phosphate.
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Why is glycogen phosphorylase alone not sufficient in in degrading glycogen?
Why is glycogen phosphorylase alone not sufficient in in degrading glycogen?
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When glycogen phosphorylase reaches a branching point in glycogen, the bonds switch from being alpha-1,4-glycosidic bonds to alpha-1,6-glycosidic bonds. It is unable to cleave these bonds, and so other enzymes (a transferase and a glucosidase) must come into play.
When glycogen phosphorylase reaches a branching point in glycogen, the bonds switch from being alpha-1,4-glycosidic bonds to alpha-1,6-glycosidic bonds. It is unable to cleave these bonds, and so other enzymes (a transferase and a glucosidase) must come into play.
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Which enzymes are required for glycogen breakdown?
Which enzymes are required for glycogen breakdown?
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Glycogen is first debranched and broken down from its non-reducing end by glycogen phosphorylase to give the product G1P, which is then converted into G6P by phosphoglutomutase. Glycogen synthase, glycogen branching enzyme, and UDP-glucose pyrophosphorylase are required for glycogen synthesis.
Glycogen is first debranched and broken down from its non-reducing end by glycogen phosphorylase to give the product G1P, which is then converted into G6P by phosphoglutomutase. Glycogen synthase, glycogen branching enzyme, and UDP-glucose pyrophosphorylase are required for glycogen synthesis.
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What are some characteristics of glycogen phosphorylase?
I. It is the rate-limiting enzyme of glycogenolysis
II. It breaks alpha 1,4 glycosidic bonds
III. It is activated by epinephrine
IV. It breaks alpha 1,6 glycosidic bonds
What are some characteristics of glycogen phosphorylase?
I. It is the rate-limiting enzyme of glycogenolysis
II. It breaks alpha 1,4 glycosidic bonds
III. It is activated by epinephrine
IV. It breaks alpha 1,6 glycosidic bonds
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Glycogen phosphorylase, the rate-limiting enzyme of glycogenolysis does not breaks alpha 1,6 glycosidic bonds. It releases glucose from glycogen by hydrolyzing alpha 1,4 glycosidic bonds until it reaches a branch point in the glycogen molecule. At this time, another enzyme, a debranching alpha 1,6 glycosidase hydrolyzes the alpha 1,6 glycosidic bonds. Glycogen phosphorylase is under regulation by many hormones, including insulin and glucagon, as well as epinephrine.
Glycogen phosphorylase, the rate-limiting enzyme of glycogenolysis does not breaks alpha 1,6 glycosidic bonds. It releases glucose from glycogen by hydrolyzing alpha 1,4 glycosidic bonds until it reaches a branch point in the glycogen molecule. At this time, another enzyme, a debranching alpha 1,6 glycosidase hydrolyzes the alpha 1,6 glycosidic bonds. Glycogen phosphorylase is under regulation by many hormones, including insulin and glucagon, as well as epinephrine.
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Which one of the following statements is incorrect?
Which one of the following statements is incorrect?
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Glycogen is mostly stored in the liver and skeletal muscle. When it is broken down in the liver, the last enzyme, a phosphatase, removes the last phosphate group to release plain glucose into the bloodstream. In the muscle, there is no need to release the glucose, so glycogen is only broken down as far as glucose-6-phosphate. Skeletal muscle cells lack the last phosphatase required to remove the phosphate from carbon 6. This isn't an obstacle, however, because the glucose-6-phosphate is already on to the second stage of glycolysis.
Glycogen is mostly stored in the liver and skeletal muscle. When it is broken down in the liver, the last enzyme, a phosphatase, removes the last phosphate group to release plain glucose into the bloodstream. In the muscle, there is no need to release the glucose, so glycogen is only broken down as far as glucose-6-phosphate. Skeletal muscle cells lack the last phosphatase required to remove the phosphate from carbon 6. This isn't an obstacle, however, because the glucose-6-phosphate is already on to the second stage of glycolysis.
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Which one of the following statements is correct?
Which one of the following statements is correct?
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Insulin is released in response to high blood glucose. It causes a signaling cascade that, in addition to other things, stops glycogenolysis. This is done by converting glycogen phosphorylase from it's active "a" form to its inactive "b" configuration. The "R" state is the active state, so the presence of glucose would not trigger the breakdown of glycogen. 5' AMP would not inhibit an inactive form of an enzyme. High AMP would mean a demand for ATP, so it would convert the enzyme to its "a" form.
Insulin is released in response to high blood glucose. It causes a signaling cascade that, in addition to other things, stops glycogenolysis. This is done by converting glycogen phosphorylase from it's active "a" form to its inactive "b" configuration. The "R" state is the active state, so the presence of glucose would not trigger the breakdown of glycogen. 5' AMP would not inhibit an inactive form of an enzyme. High AMP would mean a demand for ATP, so it would convert the enzyme to its "a" form.
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Phosphorylation of glycogen phosphorylase has what effect on the enzyme?
Phosphorylation of glycogen phosphorylase has what effect on the enzyme?
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Phosphorylation of glycogen phosphorylase activates it, converting it from its inactive B-form to its active A-form.
Phosphorylation of glycogen phosphorylase activates it, converting it from its inactive B-form to its active A-form.
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The process of glycogenolysis is an example of .
The process of glycogenolysis is an example of .
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Phosphorolysis is the name given to the addition of phosphate across a bond. Remember that in glycogenolysis, glycogen phosphorylase adds a phosphate across the a-1,4-glycosidic bonds between the glucose units of glycogen. The result is that glucose leaves as glucose-1-phosphate. If hydrolysis were performed instead of phosphorolysis, free glucose would be severed from glycogen and would be able to leave the cell.
Phosphorolysis is the name given to the addition of phosphate across a bond. Remember that in glycogenolysis, glycogen phosphorylase adds a phosphate across the a-1,4-glycosidic bonds between the glucose units of glycogen. The result is that glucose leaves as glucose-1-phosphate. If hydrolysis were performed instead of phosphorolysis, free glucose would be severed from glycogen and would be able to leave the cell.
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Which of the following statements about glycogen phosphorylase (GP) is incorrect?
Which of the following statements about glycogen phosphorylase (GP) is incorrect?
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AMP is an activator of GP, whereas ATP is an inhibitor of GP. GP cleaves the alpha 1-4 glycosidic bond between a terminal glucose molecule and the rest of the glycogen straight chain, yielding glucose-1-phosphate during glycogenolysis.
AMP is an activator of GP, whereas ATP is an inhibitor of GP. GP cleaves the alpha 1-4 glycosidic bond between a terminal glucose molecule and the rest of the glycogen straight chain, yielding glucose-1-phosphate during glycogenolysis.
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Which of the following is not a possible fate of glucose-6-phosphate?
Which of the following is not a possible fate of glucose-6-phosphate?
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When glycogen is broken down, the individual units that are removed are glucose-1-phosphate units. These are then transformed into glucose-6-phosphate molecules which are of extreme biological importance because of their ability to enter various different pathways. These pathways include glycolysis and the pentose phosphate pathway. The urea cycle, however, has to do with amino acids/proteins.
When glycogen is broken down, the individual units that are removed are glucose-1-phosphate units. These are then transformed into glucose-6-phosphate molecules which are of extreme biological importance because of their ability to enter various different pathways. These pathways include glycolysis and the pentose phosphate pathway. The urea cycle, however, has to do with amino acids/proteins.
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Which of the following statements about glycogen phosphorylase (GP) is incorrect?
Which of the following statements about glycogen phosphorylase (GP) is incorrect?
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AMP is an activator of GP, whereas ATP is an inhibitor of GP. GP cleaves the alpha 1-4 glycosidic bond between a terminal glucose molecule and the rest of the glycogen straight chain, yielding glucose-1-phosphate during glycogenolysis.
AMP is an activator of GP, whereas ATP is an inhibitor of GP. GP cleaves the alpha 1-4 glycosidic bond between a terminal glucose molecule and the rest of the glycogen straight chain, yielding glucose-1-phosphate during glycogenolysis.
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Phosphorylation of glycogen phosphorylase has what effect on the enzyme?
Phosphorylation of glycogen phosphorylase has what effect on the enzyme?
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Phosphorylation of glycogen phosphorylase activates it, converting it from its inactive B-form to its active A-form.
Phosphorylation of glycogen phosphorylase activates it, converting it from its inactive B-form to its active A-form.
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The process of glycogenolysis is an example of .
The process of glycogenolysis is an example of .
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Phosphorolysis is the name given to the addition of phosphate across a bond. Remember that in glycogenolysis, glycogen phosphorylase adds a phosphate across the a-1,4-glycosidic bonds between the glucose units of glycogen. The result is that glucose leaves as glucose-1-phosphate. If hydrolysis were performed instead of phosphorolysis, free glucose would be severed from glycogen and would be able to leave the cell.
Phosphorolysis is the name given to the addition of phosphate across a bond. Remember that in glycogenolysis, glycogen phosphorylase adds a phosphate across the a-1,4-glycosidic bonds between the glucose units of glycogen. The result is that glucose leaves as glucose-1-phosphate. If hydrolysis were performed instead of phosphorolysis, free glucose would be severed from glycogen and would be able to leave the cell.
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Phosphorylation of glycogen phosphorylase has what effect on the enzyme?
Phosphorylation of glycogen phosphorylase has what effect on the enzyme?
Tap to reveal answer
Phosphorylation of glycogen phosphorylase activates it, converting it from its inactive B-form to its active A-form.
Phosphorylation of glycogen phosphorylase activates it, converting it from its inactive B-form to its active A-form.
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The process of glycogenolysis is an example of .
The process of glycogenolysis is an example of .
Tap to reveal answer
Phosphorolysis is the name given to the addition of phosphate across a bond. Remember that in glycogenolysis, glycogen phosphorylase adds a phosphate across the a-1,4-glycosidic bonds between the glucose units of glycogen. The result is that glucose leaves as glucose-1-phosphate. If hydrolysis were performed instead of phosphorolysis, free glucose would be severed from glycogen and would be able to leave the cell.
Phosphorolysis is the name given to the addition of phosphate across a bond. Remember that in glycogenolysis, glycogen phosphorylase adds a phosphate across the a-1,4-glycosidic bonds between the glucose units of glycogen. The result is that glucose leaves as glucose-1-phosphate. If hydrolysis were performed instead of phosphorolysis, free glucose would be severed from glycogen and would be able to leave the cell.
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