Glycogen Metabolism

Question 1

What is the advantage of glycogen breakdown by phosphorolysis compared with hydrolysis?

Answer 1

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Question 2

Describe the significance of glycogenolysis in liver versus muscle.

Answer 2

The product of glycogenolysis (G1P) in muscle, is not available to other tissues, since muscle lacks the crucial enzyme glucose-6-phosphatase.

Question 3

Describe how glucose 1-phosphate is converted into glucose 6-phosphate.

Answer 3

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Question 4

Describe the phosphorylation mediated, regulation of enzyme activity.

Answer 4

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Question 5

Name the two hormones that are involved in triggering glycogenolysis and describe their specificity.

Answer 5

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Question 6

Describe the mechanism by which PKA is activated.

Answer 6

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Question 7

Describe the glycogenolysis cascade, and discuss the kinases that are involved in the pathway.

Answer 7

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Question 8

Describe the role of calcium in glycogenolysis, especially with reference to the neuromuscular stimulus.

Answer 8

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Question 9

Describe the activation of the alpha-adrenergic receptor and the associated cascade of biochemical events.

Answer 9

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Question 10

Describe the role of protein phosphatase inhibitor 1 (PPI-1) during glycogenolysis.

Answer 10

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Question 11

Describe the fight or flight response in relation to glycogen metabolism.

Answer 11

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Question 12

Describe the role of AMP and Calcium in muscle.

Answer 12

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Question 13

Describe how UDP-glucose is formed.

Answer 13

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Question 14

How are alpha 1-6 branches in glycogen formed?

Answer 14

They are formed by a (alpha-1-4)-(alpha-1-6)-glucan transferase, commonly known as branching enzyme. It transfers terminal fragments of 6-7 glucose residues to an internal glucose residue at the C-6 hydroxyl position to form a branching point.

Question 15

Describe glycogenin.

Answer 15

It is a protein that has been shown to perform primer synthesis. It autocatalytically attaches C-1 of a UDP-glucose (UDPG) to its tyrosine residue

Question 16

Describe the three major allosteric effectors and its effect on glycogen synthase-b.

Answer 16

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Question 17

Describe the properties and role of glucose 6-phosphatase in glycogen metabolism.

Answer 17

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Question 18

Describe how a futile cycle of glycogenolysis and glycogen synthesis (i.e. operating the same time) is prevented.

Answer 18

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Question 19

Describe very briefly the mode of action of alpha-adrenergic and beta-adrenergic hormones.

Answer 19

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Question 20

What are heterotrimeric G proteins?

Answer 20

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Question 21

Briefly describe how protein kinase A (PKA) is activated.

Answer 21

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Question 22

What are the products that are formed by the action of phospholipase C?

Answer 22

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Question 23

Describe the control of blood gucose level by hormones.

Answer 23

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Question 24

What enzymes or proteins are affected in Pompe’s disease?

Answer 24

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Question 25

What enzymes or proteins are affected in Cori's disease?

Answer 25

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Question 26

What enzymes or proteins are affected in McArdle's disease?

Answer 26

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Question 27

What enzymes or proteins are affected in Anderson's disease?

Answer 27

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Question 28

What enzymes or proteins are affected in Von Gierke's disease?

Answer 28

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Question 29

What enzymes or proteins are affected in Hers disease?

Answer 29

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Question 30

Explain the reason why liver glycogen phosphorylase enyme would not be prone to allosteric regulation by G6P as opposed to muscle glycogen phosphorylase.

Answer 30

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Question 31

Can you explain why glycogen phosphorylase is phosphorylated by only one kinase? Why is glycogen synthase inactivated progressively by many kinases?

Answer 31

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Question 32

Can Von Gierke's patients carry out gluconeogenesis normally? If not, explain why?

Answer 32

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Question 33

Which of the tissues (liver or muscle) would contain more total glycogen per gram of tissue?

Answer 33

The liver has ~100 g of glycogen and skeletal muscle has ~400 g of glycogen.

Question 34

What is/are the physiological advantage(s) of having branched glycogen as opposed to linear glycogen in mammals?

Answer 34

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Question 35

Can we conceive how much of liver glycogen serves for its own metabolism (aside from the glucose that is pumped into the blood)?

Answer 35

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Question 36

Descrbe the relationship of glucsose/glycogen metabolism to Type I and Type II diabetes.

Answer 36

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Question 37

Type I diabetes can be better controlled by insulin administration (true/false?)

Answer 37

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Question 38

Can we come up with a hypothesis as to why type II diabetics are obese?

Answer 38

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Question 39

Describe the biochemical basis of diabetic retinopathy.

Answer 39

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Question 40

Describe the production of glucitol/sorbitol.

Answer 40

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Question 41

What is glycation?

Answer 41

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Question 42

Describe the biochemical basis of diabetic nephropathy.

Answer 42

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Question 43

Explain the biochemical/physiological basis of diabetes being a cardiovascular problem.

Answer 43

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Question 44

Hemoglobin A1c levels are used as an indicator to assesss the severity of diabetes. Explain this in biochemical terms.

Answer 44

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Question 45

Explain the biochemical basis of hypoglycemia.

Answer 45

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Question 46

What are GLUT's?

Answer 46

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Question 47

What is the normal fasting level of glucose in the blood? (Explain it in percent and mM concentrations)

Answer 47

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Question 48

Muscle can respond to insulin, however it doesn't respond to glucagon. Explain and rationalize why evolution made it this way. (What is so special about muscle compared to liver?)

Answer 48

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Question 49

Describe the major connecting point between glycogen and gluconeogenesis metabolism.

Answer 49

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Question 50

Why are proteins prone to non-enzymatic glycation?

Answer 50

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Question 51

Explain in biochemical/biophysical terms why glucose molecule in excess concentrations is a big problem maker in tissues and organs.

Answer 51

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