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Flashcards in Glycogen Metabolism Deck (30)
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1
Q

This is the storage form of carbohydrates in animals.

A

Glycogen

2
Q

What are the primary storage sites of glycogen?

A

Liver and skeletal muscle

3
Q

This type of glycogen is more sensitive to dietary carbohydrates and is synthesized more rapidly following post-exercise glycogen depletion.

A

Proglycogen

4
Q

This type of glycogen has a much slower and constant synthesis. It is responsible for carbohydrate loading (supercompensation).

A

Macroglycogen

5
Q

How many grams of glycogen can skeletal muscle hold? Can it release glucose?

A

400 grams and skeletal muscle cannot release glucose

6
Q

How many grams of glycogen can the liver hold? Can it release glucose?

A

100 grams and the liver can release glucose

7
Q

Where would you store your glycogen?

A

Cytosol

8
Q

What is the general mechanism for glycogen synthesis?

A
  • Phosphorylate glucose
  • Make UDP-glucose
  • Initation
  • Elongation of the chain
  • Branching
9
Q

This is a protein that starts the glycogen chain with the amino acid tyrosine.

A

Glycogenin

10
Q

What is the enzyme that starts the glycogen chain?

A

Glycogen initiator synthase

11
Q

When you are resynthesizing glycogen you are using what?

A

ATP

12
Q

How many ATPs are broken down to attach each glucose for glycogen synthesis?

A

3

13
Q

What is the enzyme, type of bonds created, and location of elongation of a glycogen chain?

A

Glycogen synthase adds alpha (1–>4) bonds in the cytosol

14
Q

What is the enzyme and type of bonds created in the branching phase of glycogen synthesis?

A

Glucosyl 4:6 transferase adds alpha (1–>6) bonds

15
Q

What enzyme degrades glycogen?

A

Glycogen phosphorylase

16
Q

After glycogen has been degraded into glucose 1P what enzyme converts it into glucose 6P?

A

Phosphoglucomutase

17
Q

When is glycogen phosphorylase no longer effective at breaking down glycogen?

A

When there are four glucose molecules left prior to a branch point

18
Q

When glycogen phosphorylase is no longer effective, two new enzymes are required to continue glycogen degradation. What are they?

A
  • Glucosyl (4:4) transferase: removes the outer three glucose molecules
  • Amylo-alpha-(1,6)-glucosidase: removes the last glucose of the branch
19
Q

What are the main regulating enzymes of glycogen synthesis?

A

Glycogen synthase (sitmulates) and glycogen phosphorylase (inhibits)

20
Q

What does exercise do to GLUT4, glycogen synthesis, and insulin sensitivity?

A

GLUT4: increased translocation and increased amount of transporters
Glycogen synthesis: stimulated after exercise
Insulin sensitivity: increased after exercise

21
Q

This phase of glycogen synthesis occurs 30-60 minutes after exercise, is insulin independent, and occurs when muscle glycogen levels are relatively low and carbohydrates are provided immediately after exercise.

A

Rapid phase

22
Q

This phase of glycogen synthesis occurs several hours after exercise, is insulin dependent, is a much slower rate of glycogen synthesis, and must have carbohydrates and insulin available.

A

Slow phase

23
Q

What are the two phases of increased glucose uptake?

A

Insulin-independent: <3-6 hours post exercise, AMPK pathway stimulated, P13K pathway is temporarily inhibited.
Insulin-dependent: 3-6 to 48 hours post-exercise

24
Q

Does consumption of carbohydrates after exercise increase glycogen synthesis?

A

Yes

25
Q

Is glycogen storage higher in trained athletes than the normal individual?

A

Yes

26
Q

This is the increased in blood glucose level over the base-line level during a 2 hour period following the consumption of a defined amount of carbohydrate compared with the same amount of carbohydrate in a reference food.

A

Glycemic index

27
Q

This term is used to describe the glycemic index times the grams of carbohydrate in a serving of the food. It considers both the quantity and the quality of the carbohydrate in a meal.

A

Glycemic load

28
Q

The ____ the glycemic load, the ____ the expected elevation in blood glucose and in the insulinogenic effect of the food.

A

Higher; greater

29
Q

What factors are involved with the synthesis of glycogen?

A
  • High blood glucose
  • Insulin
  • Fructose (impacts liver not muscle)
  • Low glycogen content
  • High Energy Charge
  • ATP
30
Q

What factors are involved with the breakdown of glycogen?

A
  • Low Blood Glucose (impacts liver not muscle)
  • Glucagon (impacts liver not muscle)
  • Low Energy Charge
  • ADP, AMP
  • Calcium (muscle contraction)