Glycogen-Rosenberg

Question 1

Which organ is the main source of Glycogen during fasting?

Answer 1

The Liver

Question 2

Regarding Glycogen, what is the fundamental difference between the liver and muscle?

Answer 2

The liver liberates glycogen to yield a higher concentration of blood glucose, while the muscle retains glycogen for muscle energy.

Question 3

What are the two types of tissue that are insulin-sensitive “insulin dependent”?

Answer 3

Adipose and muscle tissue. “most abundant tissues in the body”.

Question 4

How do muscle and adipose tissue bring glucose into the cell after a meal?

Answer 4

Insulin binds a receptor tyrosine kinase –> Protein kinase b activated –> endosomes which contain glut-4 fuses with cell membrane –> glucose transport into cell.

Question 5

How do muscle and adipose tissue bring glucose into the cell during fasting conditions?

Answer 5

intracellular AMP concentration increases –> AMPK activation –> GLUT-4 membrane recruitment –> glucose transport into cell.

Question 6

Which intracellular hepatic enzyme phosphorylates glucose?

Answer 6

Glucokinase

Question 7

Which intracellular enzyme phosphorylates glucose?

Answer 7

Hexokinase

Question 8

What would the activity be “high or low” of glucokinase in starving conditions?

Answer 8

Low

Question 9

What would the activity be “high or low” of glucokinase in a diabetic patient?

Answer 9

Low

Question 10

What would the activity be “high or low” of glucokinase after a meal?

Answer 10

High

Question 11

What would the activity be “high or low” of glucokinase in a patient on a low carbohydrate diet?

Answer 11

Low

Question 12

Which enzyme would work better for the brain: Hexokinase or Glucokinase and why?

Answer 12

Hexokinase because it has a higher affinity for glucose.

Question 13

Under fasting conditions would glucose be phosphorylated or dephosphorlyated in the liver?

Answer 13

Dephosphorylated to liberate glucose into the blood

Question 14

Most cells utilize GLUT-2 only to internalize glucose. Which cells also utilize GLUT-2 to transport glucose out of the cell?

Answer 14

Hepatocytes

Question 15

Glycogen synthase

Answer 15

transfers glucose to glycogen primer that has “glycogenin”.

Question 16

Does it require energy to make glycogen?

Answer 16

Yes, 2 ATP. One to phosphorylate glucose and one to make UTP from UDP.

Question 17

Glycogen + Glycogen phosphorylase =

Answer 17

G-1-P via inorganic phosphorolysis @ non-reducing end of glycogen molecule.

Question 18

Which enzyme is unique to the liver that takes G-6-P to Glucose?

Answer 18

Glucose-6- Phosphotase

Question 19

Two types of Regulation:

Answer 19

Allosteric and Hormonal

Question 20

Allosteric

Answer 20

Enzyme has a site which changes the catalytic activity. Concentration levels are the key.

Question 21

When is Glycogen phosphorylase structally active?

Answer 21

When it is phosphorylated.

Question 22

When are Glycogen phosphorylase and Glycogen synthase phosphorylated? During fasting or after a meal?

Answer 22

Fasting.

Question 23

When is Glycogen synthase structally active?

Answer 23

When it is dephosphorylated.

Question 24

Remember: When we fast we…….

Answer 24

Phosphorylate!!!!!

Question 25

Glucagon is secreted when blood glucose increases or decreases?

Answer 25

Decreases

Question 26

T/F Glucagon works only on the liver.

Answer 26

True. Makes liver break down glycogen to release glucose into the blood.

Question 27

T/F Epinephrine targets the liver and muscle.

Answer 27

True.

Question 28

Which 3 enzymes Deactivate Glycogen synthase-A?

Answer 28

PKA, GSK-3, Phosphorylase Kinase

Question 29

What would be favored in the liver by increased intracellular levels of epinephrine? glycogen breakdown or synthesis?

Answer 29

Breakdown.

Question 30

What would be favored in the liver by increased intracellular levels of glucagon? glycogen breakdown or synthesis?

Answer 30

Breakdown.

Question 31

4 functions of insulin:

Answer 31

limit the production of cAMP activate hepatic protein phosphatases activate the phosphodiesterase that converts cAMP to AMP. Inactivates glycogen synthase kinase-3.

Question 32

When Insulin:Glucagon ratio is high what would be permitted?

Answer 32

Glycogen synthesis.

Question 33

How does glycogen inhibit its own formation?

Answer 33

by inhibiting dephosphorylation of glycogen synthase by phosphoprotein phosphatase or by making the active form of the synthase a better substrate for protein kinase A.

Question 34

Glycogen Storage Von Gierke's disease is characterized by a defect in which enzyme?

Answer 34

Glucose-6-phosphotase

Question 35

Glycogen Storage Cori's Disease is characterized by a defect in which enzyme?

Answer 35

Amylo-1,6-glucosidase (Debranching Enzyme)

Question 36

Glycogen Storage Anderson's disease is characterized by a defect in which enzyme?

Answer 36

Branching Enzyme "Alpha-1,4 --> Alpha-1,6"

Question 37

Glycogen Storage Mc Ardle's disease is characterized by a defect in which enzyme?

Answer 37

Glycogen phosphorylase

Question 38

Glycogen Storage Hers's disease is characterized by a defect in which enzyme?

Answer 38

Glycogen phosphorylase

Question 39

What are Clinical features of Von Gierke's disease?

Answer 39

Massive enlargement of the liver, Failure to thrive, Severe hypoglycemia, ketosis, hyperuricemia, hyperlipemea?

Question 40

What are clinical features of Cori's disease?

Answer 40

Like Von Gierkes but milder.

Question 41

What are clinical features of Anderson's Disease?

Answer 41

Progressive cirrhosis of the liver. Liver failure causes death usually before age two

Question 42

What are clinical features Mc Ardle's disease?

Answer 42

Limited ability to perform strenuous exercise due to muscle cramps. Otherwise patient is normal and well developed.

Question 43

What are clinical features of Her's Disease?

Answer 43

Like type 1 but milder.

Question 44

What is glycogen's structure and concentration like in Von gierkes disease?

Answer 44

Increased amount and Normal structure

Question 45

What is glycogen's structure and concentration like in Cori's disease?

Answer 45

Increased amount and short outer branches

Question 46

What is glycogen's structure and concentration like in Anderson's disease?

Answer 46

Normal amount with very long outer branches

Question 47

What is glycogen's structure and concentration like in Mc Ardles disease?

Answer 47

Moderately increased amount with normal structure

Question 48

What is glycogen's structure and concentration like in Her's Disease?

Answer 48

Increased amount.