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Questions and Answers
What type of glycosidic bond is primarily found in glycogen?
What type of glycosidic bond is primarily found in glycogen?
- α(1→2) linkage
- β(1→6) linkage
- α(1→4) linkage (correct)
- β(1→4) linkage
During which state does the liver increase its glycogen stores?
During which state does the liver increase its glycogen stores?
- Starvation
- Sleep
- Well-fed state (correct)
- Short fasting period
What is the molecular mass range of a single glycogen molecule?
What is the molecular mass range of a single glycogen molecule?
- 10^6 to 10^7 daltons (correct)
- 10^5 to 10^6 daltons
- 10^3 to 10^4 daltons
- 10^4 to 10^5 daltons
Where are glycogen molecules typically found within a cell?
Where are glycogen molecules typically found within a cell?
How is muscle glycogen affected by short periods of fasting?
How is muscle glycogen affected by short periods of fasting?
Which enzyme is responsible for converting glucose 1-phosphate to glucose 6-phosphate?
Which enzyme is responsible for converting glucose 1-phosphate to glucose 6-phosphate?
McArdle Syndrome is caused by a deficiency in which enzyme?
McArdle Syndrome is caused by a deficiency in which enzyme?
Which enzyme cleaves the remaining single glucose residue from the branch point during glycogenolysis?
Which enzyme cleaves the remaining single glucose residue from the branch point during glycogenolysis?
Which glycogen storage disease is characterized by fasting hypoglycemia and an abnormal glycogen structure?
Which glycogen storage disease is characterized by fasting hypoglycemia and an abnormal glycogen structure?
Which clinical manifestation is NOT associated with Pompe Disease?
Which clinical manifestation is NOT associated with Pompe Disease?
What is the primary cause of muscle weakness in McArdle Syndrome?
What is the primary cause of muscle weakness in McArdle Syndrome?
Which glycogen storage disease is associated with myoglobinemia?
Which glycogen storage disease is associated with myoglobinemia?
Which of the following steps is regulated by hormonal signals?
Which of the following steps is regulated by hormonal signals?
Which of the following is NOT a primary source of blood glucose?
Which of the following is NOT a primary source of blood glucose?
What is the preferred energy source for the brain?
What is the preferred energy source for the brain?
Which type of cells are specifically mentioned as requiring glucose due to having few or no mitochondria?
Which type of cells are specifically mentioned as requiring glucose due to having few or no mitochondria?
What role does muscle glycogen primarily serve?
What role does muscle glycogen primarily serve?
Approximately how much glycogen is stored in a well-fed adult liver?
Approximately how much glycogen is stored in a well-fed adult liver?
Which process provides a rapid release of glucose in the absence of dietary sources?
Which process provides a rapid release of glucose in the absence of dietary sources?
What percentage of fresh weight of resting muscle does glycogen make up?
What percentage of fresh weight of resting muscle does glycogen make up?
Which metabolic pathway is immediately engaged when glycogen stores are depleted?
Which metabolic pathway is immediately engaged when glycogen stores are depleted?
Which type of glycogen storage disease is characterized by Glucose 6-Phosphatase deficiency?
Which type of glycogen storage disease is characterized by Glucose 6-Phosphatase deficiency?
Which tissues are primarily affected by Glucose 6-Phosphate Translocase deficiency (Type Ib)?
Which tissues are primarily affected by Glucose 6-Phosphate Translocase deficiency (Type Ib)?
What is a symptom of severe prolonged fasting associated with Type Ib disease?
What is a symptom of severe prolonged fasting associated with Type Ib disease?
What is a characteristic symptom of Von Gierke Disease not directly related to glucose metabolism?
What is a characteristic symptom of Von Gierke Disease not directly related to glucose metabolism?
What treatment is specifically mentioned for managing symptoms of Type Ib disease?
What treatment is specifically mentioned for managing symptoms of Type Ib disease?
Which molecule serves as the initial acceptor of glucose residues from UDP-glucose during glycogen synthesis?
Which molecule serves as the initial acceptor of glucose residues from UDP-glucose during glycogen synthesis?
What type of bond is primarily formed by glycogen synthase during glycogen elongation?
What type of bond is primarily formed by glycogen synthase during glycogen elongation?
Which amino acid's side chain hydroxyl group serves as the site for the initial glucosyl unit attachment on glycogenin?
Which amino acid's side chain hydroxyl group serves as the site for the initial glucosyl unit attachment on glycogenin?
What enzyme helps in re-phosphorylating UDP to UTP during glycogen synthesis?
What enzyme helps in re-phosphorylating UDP to UTP during glycogen synthesis?
Where does glycogenin remain localized in the glycogen structure?
Where does glycogenin remain localized in the glycogen structure?
What is the primary function of UDP-glucose in glycogen synthesis?
What is the primary function of UDP-glucose in glycogen synthesis?
Which enzyme catalyzes the conversion of glucose 6-phosphate to UDP-glucose?
Which enzyme catalyzes the conversion of glucose 6-phosphate to UDP-glucose?
Which specific reaction is catalyzed by glycogenin via autoglucosylation?
Which specific reaction is catalyzed by glycogenin via autoglucosylation?
What primarily characterizes lysosomal storage diseases?
What primarily characterizes lysosomal storage diseases?
During what condition does glycogenolysis in the liver accelerate?
During what condition does glycogenolysis in the liver accelerate?
Which statement accurately describes the hormonal regulation of glycogen synthase and glycogen phosphorylase?
Which statement accurately describes the hormonal regulation of glycogen synthase and glycogen phosphorylase?
How does calcium (Ca^{2+}) activate glycogen phosphorylase during muscle contraction?
How does calcium (Ca^{2+}) activate glycogen phosphorylase during muscle contraction?
What role does AMP play in muscle during extreme conditions of anoxia?
What role does AMP play in muscle during extreme conditions of anoxia?
Which hormone stimulates glycogen degradation in both muscle and liver?
Which hormone stimulates glycogen degradation in both muscle and liver?
Which process is accelerated during the well-fed state in the liver?
Which process is accelerated during the well-fed state in the liver?
What is the effect of insulin on glycogen degradation?
What is the effect of insulin on glycogen degradation?
Which enzyme reconverts glycogen synthase b to the active 'a' form?
Which enzyme reconverts glycogen synthase b to the active 'a' form?
What molecule allosterically inhibits glycogen phosphorylase a in the liver but not in muscle?
What molecule allosterically inhibits glycogen phosphorylase a in the liver but not in muscle?
What is the effect of cAMP on glycogen synthase?
What is the effect of cAMP on glycogen synthase?
Which state correlates with the increased activation of glycogen synthase b by glucose 6-phosphate?
Which state correlates with the increased activation of glycogen synthase b by glucose 6-phosphate?
What triggers the activation of muscle phosphorylase kinase b during muscle contraction?
What triggers the activation of muscle phosphorylase kinase b during muscle contraction?
How does the binding of calcium to calmodulin affect phosphorylase kinase b?
How does the binding of calcium to calmodulin affect phosphorylase kinase b?
What is the role of protein kinases in the regulation of glycogen synthase?
What is the role of protein kinases in the regulation of glycogen synthase?
Which molecule is NOT associated with activating glycogen degradation in muscle?
Which molecule is NOT associated with activating glycogen degradation in muscle?
Which enzyme catalyzes the synthesis of cAMP following the binding of glucagon or epinephrine to GPCR?
Which enzyme catalyzes the synthesis of cAMP following the binding of glucagon or epinephrine to GPCR?
What is the role of protein kinase A (PKA) in glycogen metabolism?
What is the role of protein kinase A (PKA) in glycogen metabolism?
How is glycogen phosphorylase regulated in glycogen degradation?
How is glycogen phosphorylase regulated in glycogen degradation?
Which statement best describes the summary of the regulation of glycogen degradation?
Which statement best describes the summary of the regulation of glycogen degradation?
Which of the following is true for glycogen synthase regulation?
Which of the following is true for glycogen synthase regulation?
What is the function of inhibitor proteins in the regulation of glycogen metabolism?
What is the function of inhibitor proteins in the regulation of glycogen metabolism?
Which hormones are primarily involved in signaling the need for glycogen degradation?
Which hormones are primarily involved in signaling the need for glycogen degradation?
What role does protein phosphatase 1 play in glycogen metabolism?
What role does protein phosphatase 1 play in glycogen metabolism?
Which molecule forms a complex with $Ca^{2+}$ to activate hepatic phosphorylase kinase b during the 'fight or flight' response?
Which molecule forms a complex with $Ca^{2+}$ to activate hepatic phosphorylase kinase b during the 'fight or flight' response?
What triggers the release of $Ca^{2+}$ from the ER into the cytoplasm in hepatocytes?
What triggers the release of $Ca^{2+}$ from the ER into the cytoplasm in hepatocytes?
How does AMP activate muscle glycogen phosphorylase without phosphorylation?
How does AMP activate muscle glycogen phosphorylase without phosphorylation?
Which enzyme's activation is associated with high AMP concentrations under anoxia and ATP depletion in muscles?
Which enzyme's activation is associated with high AMP concentrations under anoxia and ATP depletion in muscles?
A defect in which enzyme type results in glycogen storage diseases (GSDs) leading to abnormal glycogen structure or accumulation?
A defect in which enzyme type results in glycogen storage diseases (GSDs) leading to abnormal glycogen structure or accumulation?
Which linkage type is found at the branch points of glycogen after about eight to ten glucosyl residues?
Which linkage type is found at the branch points of glycogen after about eight to ten glucosyl residues?
During the 'fight or flight' response, which secondary messenger is responsible for hepatic glycogenolysis?
During the 'fight or flight' response, which secondary messenger is responsible for hepatic glycogenolysis?
Which enzyme forms the primer required for glycogen synthesis?
Which enzyme forms the primer required for glycogen synthesis?
What is the immediate product formed when glucose is transferred from UDP-glucose to the nonreducing end of glycogen?
What is the immediate product formed when glucose is transferred from UDP-glucose to the nonreducing end of glycogen?
Which enzyme is responsible for creating branches within the glycogen molecule?
Which enzyme is responsible for creating branches within the glycogen molecule?
What is the function of the enzyme amylo-α(1→4)→(1→6)-transglucosidase?
What is the function of the enzyme amylo-α(1→4)→(1→6)-transglucosidase?
What is the primary product obtained when glycogen is degraded?
What is the primary product obtained when glycogen is degraded?
How many glucosyl residues apart are branches located on average in glycogen?
How many glucosyl residues apart are branches located on average in glycogen?
Which enzyme is responsible for sequentially cleaving α(1→4) glycosidic bonds during glycogen degradation?
Which enzyme is responsible for sequentially cleaving α(1→4) glycosidic bonds during glycogen degradation?
What distinguishes amylose from glycogen?
What distinguishes amylose from glycogen?
What is a 'limit dextrin' in the context of glycogen metabolism?
What is a 'limit dextrin' in the context of glycogen metabolism?
Which coenzyme is required by glycogen phosphorylase for its activity?
Which coenzyme is required by glycogen phosphorylase for its activity?
What happens to the nonreducing ends of glycogen after the action of amylo-α(1→4)→(1→6)-transglucosidase?
What happens to the nonreducing ends of glycogen after the action of amylo-α(1→4)→(1→6)-transglucosidase?
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Study Notes
Here are the study notes for the text:
Degradation of Glycogen - Glycogenolysis
- Glycogen degradation involves 3 steps:
- Step 1: Glycogen phosphorylase cleaves alpha 1,4 glycosidic bonds in the glycogen molecule to form glucose 1-phosphate
- Step 2: Debranching enzyme moves a block of 3 glucose residues from a branch point to the end of a glycogen chain and cleaves the remaining single glucose residue from the branch point
- Step 3: Phosphoglucomutase converts glucose 1-phosphate to glucose 6-phosphate
Glycogen Storage Diseases (GSDs)
- Caused by defects in enzymes involved in glycogen metabolism
- Examples:
- Type V: McArdle Syndrome - deficiency in skeletal muscle glycogen phosphorylase
- Type II: Pompe Disease - deficiency in lysosomal alpha-1,4-glucosidase
- Type III: Cori Disease - deficiency in debranching enzyme and/or phosphoglucomutase
Synthesis of Glycogen (Glycogenesis)
- Involves 2 stages:
- Initiation: Glycogenin serves as a primer for glycogen synthesis, and glycogen synthase elongates the glycogen chain
- Elongation: Glycogen synthase catalyzes the transfer of glucose from UDP-glucose to the non-reducing end of the growing chain
- Branching: Branching enzyme (amylo-alpha(1→4)→(1→6)-transglucosidase) creates branches in the glycogen molecule
Regulation of Glycogen Synthesis and Degradation
- Hormonal regulation:
- Insulin inhibits glycogen degradation and stimulates glycogen synthesis
- Glucagon and epinephrine stimulate glycogen degradation and inhibit glycogen synthesis
- Allosteric regulation:
- Glycogen synthase is activated by glucose 6-phosphate and inhibited by ATP and ADP
- Glycogen phosphorylase is activated by Ca²⁺ and inhibited by ATP and glucose 6-phosphate
- Calcium activation:
- In muscle, Ca²⁺ binds to calmodulin, which activates phosphorylase kinase b
- In liver, epinephrine binds to α-adrenergic receptors, leading to Ca²⁺ release and activation of phosphorylase kinase b
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