Questions:

1. All of the following statements about glycogen are true EXCEPT
  1. A branched polymer made from glucose with a variable molecular weight between 10 and 100 million
  2. Contains chains of glucosyl units linked by alpha-1,4 bonds with alpha-1,6 branches
  3. The many glucosyl residues that are attached to the fatty acid glycogennin are designated as the reducing ends of the polymer
  4. The other ends of all the branches are called the nonreducing ends and there are many many nonreducing ends
  5. The enzymes involved in glycogen synthesis and degradation are bound to the surface of the glycogen particles.
2. Which of the following statements about glycogen and its catabolism is NOT true?
  1. The function of glycogen in liver is to supply glucose to the blood when needed
  2. The function of glycogen in muscle is to supply energy for muscle contraction
  3. When glycogenolysis is active in liver, glycolysis is usually inactive
  4. When glycogenolysis in active in muscle, glycolysis is usually active
  5. Muscle, but not liver, has the enzyme glucose-6-phosphatase
3. In the liver, glucagon will activate
  1. Glycolysis and glycogenolysis
  2. Glycolysis and glycogen synthesis
  3. Gluconeogenesis and glycogenolysis
  4. Gluconeogenesis and glycogen synthase
  5. Gluconeogenesis and glycogen synthesis
4. Which of the following pairs would represent a futile cycle if they were both activated at the same time?
  1. Glycolysis and glycogenolysis
  2. Glycolysis and glycogen synthesis
  3. Gluconeogenesis and glycogenolysis
  4. Gluconeogenesis and glycolysis
  5. Gluconeogenesis and glycogen synthesis
5. When glycogen is synthesized in both the liver and muscle, all of the following are true EXCEPT
  1. Glucose enters the liver cell and is phosphorylated by hexokinase to become glucose-6-phosphate
  2. The isomerase, phosphoglucomutase, converts glucose-6-P to glucose-1-P
  3. Glucose-1-P is activated by UDP-glucose pyrophosphorylase to produce UDP-glucose and PPi
  4. Glucose is transferred from UDP-glucose to a glycogen molecule by glycogen synthase
  5. Glycogen synthase is the control enzyme
6. When glycogen is degraded (catabolized), all of the following occur in both liver and muscle EXCEPT
  1. Active glycogen phosphorylase catalyzes the phosphorolysis of alpha-1,4-glucosidic bonds in glycogen
  2. Debranching enzyme catalyzes the hydrolysis of alpha-1,6-glucosidic bonds in glycogen
  3. Glucose-1-P is converted to glucose-6-P by phosphoglucomutase
  4. The conversion of glycogen phosphorylase a to glycogen phosphorylase b activates glycogenolysis.
  5. High concentrations of glucose or AMP act as important control factors of glycogenloysis
7. All of the following statements about glycogen storage diseases are true EXCEPT
  1. The pathology is usually associated with the accumulation of too much glycogen in all cells of the body
  2. In McArdle’s disease the defect is in glycogen phosphorylase
  3. In McArdle’s disease, not enough energy can be supplied by anaerobic glycolysis during vigorous exercise
  4. In Von Gierke’s disease, glucose-6-phosphatase is deficient
  5. In Von Gierke’s disease, patients often suffer from fasting hypoglycemia
8. Which of the following statements about hormonal levels during different states is true?
  1. During the time you are eating a high carbohydrate mixed meal, the insulin to glucagon ratio will decrease
  2. When passing from the fed to fasting state, insulin and glucagon usually decrease
  3. When a person leaves surgery, insulin is usually high and glucagon, catecholamines, and cortisol are low
  4. When playing basketball, epinephrine is usually low and insulin is high
  5. After running for 20 miles, epinephrine, glucagon and cortisol are high and insulin is low
9. Which statement about glucose and liver is NOT true?
  1. A high carbohydrate meal will raise the level of blood glucose
  2. A mixed meal will raise the level of blood glucose
  3. Since the entrance of glucose into liver cells is passive, high blood glucose causes high glucose concentrations in the cytosol
  4. Glucokinase will convert glucose to glucose-6-P when glucose concentrations are high
  5. High glucose concentrations will activate glycogen synthesis and glycogenolysis in liver
10. All of the following statements concerning glycogen synthesis and glycogenolysis are true EXCEPT
  1. High blood glucose and high insulin will activate glycogen synthesis and inhibit glycogen phosphorylase
  2. A low insulin to glucagon ratio will activate glycogen phosphorylase and inhibit glycogen synthase
  3. Exercise will increase catecholamines, activate glycogen phosphorylase and inhibit glycogen synthase
  4. Being hit in the head with a bat will activate glycogen synthesis and inhibit glycogen phosphorylase
  5. Taking this test will activate glycogen phosphorylase and inhibit glycogen synthase
11. All of the following statements about blood glucose and muscle are true EXCEPT
  1. Increased blood glucose will increase insulin and cause more Glut-4 (glucose transporter-4) to enter the cell membrane
  2. Increased insulin will activate glycogen synthase and inhibit glycogen phosphorylase
  3. Striated muscles do not have glucagon receptors and so glucagon does not have an effect on muscle glycogen phosphorylase
  4. Catecholamines cause more glucagon and insulin to be released during exercise
  5. Catecholamines activate the cAMP cascade and glycogen phosphorylase but inhibit glycogen synthase
12. When the insulin to glucagon ratio fall when entering a fast or when you begin to exercise, all following will occur EXCEPT
  1. Glycogen synthase will be inactivated by phosphorylation by protein kinase A
  2. Glycogen phosphorylase will be activated by phosphorylation by phosphorylase kinase
  3. Phosphorylase kinase will be activated by phosphorylation by protein kinase A
  4. Increased cAMP will bind to and remove the regulatory subunits of protein kinase A
  5. Binding to GTP will activate a Gαi protein. The activated Gαi protein will inhibit adenylate cyclase
13. All of the following statements about protein phosphatases are true EXCEPT
  1. Protein phosphatases remove phosphate groups from proteins that have been phosphorylated
  2. Insulin activates protein phosphatases and removes phosphate groups added by the cAMP cascade
  3. The cAMP cascade can inhibit phosphatases
  4. When changing from the fasting state to the fed state, the protein phosphatases go from being slightly active to being very active
  5. It takes a long time for the phosphatases to reverse the action of the cAMP cascade
14. When insulin activates protein phosphatase, then protein phosphatase does all of the following EXCEPT
  1. Activates glycogen synthase by dephosphorylation
  2. Activates phosphorylase kinase by dephosphorylation
  3. Inactivates glycogen phosphorylase by dephosphorylation
  4. Activates pyruvate kinase by dephosphorylation
  5. Activates acetyl CoA carboxylase by dephosphorylation
15. Following the ingestion of carbohydrate, the glucose concentration in the cytosol of liver cells increases.  The increased glucose does all of the following EXCEPT
  1. Binds to phosphorylase a at an allosteric site and changes its conformation
  2. Inhibits both glycogen phosphorylase and glycogen synthase
  3. Causes a change in conformation of phosphorylase a that is a better substrate for protein phosphatase
  4. Causes phosphorylase a to loose its phosphate and become phosphorylase b
  5. Causes glycogen phosphorylase to lose its activity
16. The insulin to glucagon ratio is low as it usually is in both Type I and Type II diabetics.  During and immediately after a high carbohydrate meal, you would expect
  1. The storage of glucose in muscle to be less than normal for type 2 patients but normal for type 1 patients
  2. The storage of glucose in muscle to be less than normal for type 1 patients but normal for type 2 patients
  3. Insulin resistance would play no role in glycogen storage in type 2 patients
  4. The storage of glucose in muscle and liver to be less than normal
  5. The storage of glucose in muscle and liver to be greater than normal
17. At the same time that epinephrine activates the β-receptors it also binds to α1-receptors.  When the α1-receptors is activated, all of the following result EXCEPT
  1. The phosphorylation and inactivation of glycogen synthase
  2. The activation of glycogen phosphorylase by conversion of phosphorylase a to phosphorylase b
  3. The activation of phosphorylase kinase by Ca++-calmodulin
  4. The increase in inositol trisphosphate and release of Ca++ from the endoplasmic reticulum
  5. The activation of phospholipase C and the production of diacylglycerol
18. All of the following will result in activation of glycogen phosphorylase in skeletal muscle EXCEPT
  1. Increased concentrations of AMP from contraction of muscle
  2. Increased epinephrine and cAMP
  3. Increased cytosolic [Ca++]
  4. Increased protein phosphatase
  5. Increased activity of glycogen phosphorylase kinase
19. Comparing metabolism before and after birth in a normal newborn,
  1. The concentration of epinephrine will be higher before birth
  2. The concentration of glucagon will be higher before birth
  3. The concentration of insulin will be higher after birth
  4. Blood sugar will be higher after birth
  5. Fatty acid catabolism for energy will be important after birth
20. Jim, a 19-year-old body builder, was rushed to the hospital emergency room in a coma.  He had not eaten for 4 hours and had injected himself with a large dose of insulin about 90 minutes ago, just before beginning what was to be a two-hour workout.  All of the following contributed to his hypoglycemic coma EXCEPT
  1. Insulin inhibited gluconeogenesis in the liver
  2. Insulin inhibited glycogen phosphoryalse in the liver
  3. Insulin increased Glut4 in the muscle membrane
  4. Insulin inhibited the mobilization of free fatty acid from adipose and the entrance into liver mitochondria
  5. Insulin increased the energy available for gluconeogenesis in the liver
21. When glycogen is synthesized in both the liver and muscle, all of the following are true EXCEPT
  1. Glucose-1-P is activated by UDP-glucose pyrophosphorylase to produce UDP-glucose and PPi
  2. Free energy of hydrolysis of pyrophosphate (PPi) helps to drive the glycogen synthetic pathway forward
  3. Glycogen synthase adds glucose units to glycogen using alpha-1,4-glucosidic bonds
  4. Branching enzyme breaks alpha-1,6-glucosidic bonds and forms alpha-1,4-glucosidic bonds
  5. Branching enzymes moves polymers containing 6 to 8 glucose units
22. A high carbohydrate of mixed meal will cause the release of insulin as one goes from the fasting to the fed state. The insulin, in turn, causes the activation of protein phosphatase in liver. Protein phosphatase causes all of the following EXCEPT
  1. The hydrolysis of phosphate on pyruvate kinase will allow glycolysis to occur
  2. The removal of phosphate from phosphofructokinase-2/fructose-2,6-bisphosphatase will increase the concentration of fructose-2,6-bisphosphate
  3. The hydrolysis of phosphate from acetyl CoA carboxylase and the production of malonyl CoA
  4. The activation of Carnitine Palmitoyl CoA transferase I
  5. The activation of Glycogen synthase and the inhibition of glycogen phosphorylase and glycogen phosphorylase kinase
23. During glycogen synthesis, the UDP-glucose pyrophosphorylase reaction produces pyrophosphate (PPi) as one of its products.  Which of the following statements is NOT true?
  1. PPi is hydrolyzed to 2 Pi by inorganic pyrophosphatase
  2. PPi contains a high energy bond
  3. The hydrolysis of PPi provides the driving force for the synthesis of glucose-1-phosphate and GTP from UDP-glucose and pyrophosphate.
  4. Without the hydrolysis of PPi, the UDP-glucose pyrophosphorylase reaction would be reversible
  5. In vivo, hydrolysis of PPi causes glycogen synthesis to be irreversible

Answers:

1. Answer: C. Chapter 28, Objective 1: Describe the glycogen molecule. Back to question 1.
2. Answer: E. Chapter 28, Objective 2: What are the functions of glycogen in liver and skeletal muscle? Why must glucose-6-phosphate produced from glycogen in muscle enter glycolysis? Why does glucose produced from glycogen in liver usually enter the blood stream instead of glycolysis? Back to question 2.
3. Answer: C. Chapter 28, Objective 3: What effect does glucagon have upon glycogenolysis and gluconeogenesis in the liver? Back to question 3.
4. Answer: D. Chapter 28, Objective 4: Use the activation or inhibition of glycogen synthesis or glycogenolysis to explain the concept of a futile cycle and how a futile cycle is usually prevented. Back to question 4.
5. Answer: A. Chapter 28, Objective 5: Describe the pathway for glycogen synthesis from glucose in liver and muscle: Name, Function, Substrates, Products, Control Enzyme, Regulation, Compartment. Back to question 5.
6. Answer: D. Chapter 28, Objective 6: Describe the pathway for glycogen degradation to glucose or glucose-6-phosphate in liver and muscle: Name, Function, Substrates, Products, Control Enzyme, Regulation, Compartment. Back to question 6.
7. Answer: A. Chapter 28, Objective 7: Briefly, what is Von Gierke's disease? What is McArdle's disease? Back to question 7.
8. Answer: E. Chapter 28, Objective 8: What is the effect of a high carbohydrate meal, fasting, or stress upon the blood concentrations of insulin, glucagon, and epinephrine? Back to question 8.
9. Answer: E. Chapter 28, Objective 9: What is the effect of a high carbohydrate meal upon blood glucose and the glucose in liver cells? Back to question 9.
10. Answer: D. Chapter 28, Objective 10: What is the effect of changes in the insulin/glucagon ratio, blood glucose or epinephrine upon glycogen synthesis and glycogen degradation in the liver? Back to question 10.
11. Answer: D. Chapter 28, Objective 11: What is the effect of changes in the insulin, blood glucose or epinephrine upon glycogen synthesis or glycogen degradation in muscle? Back to question 11.
12. Answer: E. Chapter 28, Objective 12: In order of their activation, be able to name and give the reason for the activation of all the intermediates in the cAMP cascade in liver. Start with a decrease in the insulin/glucagon ratio or an increase in epinephrine and end with the change in activity of glycogen synthase, phosphorylase kinase and phosphorylase a? Back to question 12.
13. Answer: E. Chapter 28, Objective 13: What role does protein phosphatase have in the cAMP cascade? How is protein phosphatase activated or inhibited? Back to question 13.
14. Answer: B. Chapter 28, Objective 14: What is the effect of insulin upon the cAMP cascade? Back to question 14.
15. Answer: B. Chapter 28, Objective 15: Following the ingestion of carbohydrate, the glucose concentration in the cytosol of liver cells increases. What effect does this have upon phosphorylase a? Back to question 15.
16. Answer: D. Chapter 28, Objective 16: When the insulin to glucagon ratio is low as it usually is in both Type I and Type II diabetics, how is the storage of glucose in muscle and liver affected after a high carbohydrate meal? Why? What happens to blood glucose? Back to question 16.
17. Answer: B. Chapter 28, Objective 17: In order of their activation, be able to name and give the reason for the activation of the intermediates in the inositol trisphosphate and diacylglycerol cascade in liver. Start with epinephrine binding to an a1-receptor and finish with the change in activity of glycogen synthase and glycogen phosphorylase a? Limit the answer to the terms a1-receptor, G-protein, phospholipase C, phosphatidylinositol bisphosphate, IP3, diacylglycerol, protein kinase C, calcium release from endoplasmic reticulum, Ca2+, calmodulin, Ca2+-calmodulin, phosphorylase kinase, phosphorylase a, phosphorylase b, glycogen synthase a, and glycogen synthase b. Back to question 17.
18. Answer: D. Chapter 28, Objective 18: What are the three major activators of phosphorylase in muscle? Back to question 18.
19. Answer: E. Chapter 28, Objective 19: Concerning Getta Carbo: Compare the relative concentrations of insulin, glucagon, and epinephrine before labor and after delivery. Why was her blood glucose low? Why is the oxidation of fatty acids by the liver important during the first five or six hours? Back to question 19.
20. Answer: E. Chapter 28, Objectives 20: Concerning Jim Bodie: Jim injected insulin just before exercise. What were the affects upon the pathways and transport mechanisms of the liver and muscle that led to his hypoglycemic coma? Back to question 20.
21. Answer: D. Chapter 28, Objectives 5: Describe the pathway for glycogen synthesis from glucose in liver and muscle: Name, Function, Substrates, Products, Control Enzyme, Regulation, Compartment. Back to question 21.
22. Answer: D. Chapter 28, Objectives 14: Describe the pathway for glycogen synthesis from glucose in liver and muscle: Name, Function, Substrates, Products, Control Enzyme, Regulation, Compartment. Back to question 22.
23. Answer: C. Chapter 28, Objectives 5: Describe the pathway for glycogen synthesis from glucose in liver and muscle: Name, Function, Substrates, Products, Control Enzyme, Regulation, Compartment. Back to question 23.