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Biochem Exam 4 > Glycogen > Flashcards

Glycogen Flashcards

1
Q

What are the 4 main enzymes in glycogen degradation?

A

Phosphorylase
Mutase
transferase
alpha-1,6-glucosidase

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2
Q

What does phosphorylase do in glycogen degradation?

A

Breaks alpa-1,4-glycosidic bonds of terminal molecules from glycogen to release G1P

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3
Q

What does mutase do in glycogen degradation?

A

Converts G1P to G6P

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4
Q

What does transferase do in glycogen degradation?

A

Moves 3 molecules from branch to main chain to make available for phosphorylase

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5
Q

What does alpha-1,6-glucosidase do in glycogen degradation?

A

Breaks branch bond

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6
Q

What is the key regulatory enzyme of glycogen breakdown?

A

Glycogen phosphorylase

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7
Q

What is the active form of phosphorylase?

A

Phosphorylase a

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8
Q

What is the inactive form of phosphorylase?

A

Phosphorylase b

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9
Q

What is the active state of phosphorylase?

A

R

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10
Q

What is the inactive state of phosphorylase?

A

T

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11
Q

What state does phosphorylase a favor?

A

R

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12
Q

What state does phosphorylase b favor?

A

T

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13
Q

Which phosphorylase has a phosphorylated serine residue?

A

Phosphorylase a

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14
Q

What enzyme converts phosphorylase b to phosphorylase a?

A

Phosphorylase kinase

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15
Q

When is phosphorylase kinase maximally active?

A

When phosphorylated and bound to calcium

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16
Q

When is phosphorylation of phosphorylase kinase stimulated?

A

Signaling cascade of glucagon and epinephrine

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17
Q

What is the default phosphorylase in the muscle?

A

Phosphorylase b in T state

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18
Q

What is the default phosphorylase in the liver?

A

Phosphorylase a in the R state

19
Q

How are phosphorylase a and b interconverted in the muscle?

A

T to R- 2 AMP
R to T- 2 ATP 2 G6P

20
Q

How are phosphorylase a and b interconverted in the liver?

A

R to T- 2 glucose

21
Q

What are the main steps of glycogen synthesis?

A

Glycogenin
UDP-glucose
Glycogen synthase
Branching enzyme

22
Q

What does glycogenin do?

A

Generates a 10 glucose residue chain for glycogen

23
Q

What is UDP-glucose?

A

activated carrier of glucose

24
Q

What does glycogen synthase do?

A

Catalyzes transfer of glucose from UDP-glucose to glycogen

25
Q

What does branching enzyme do?

A

Cleaves alpa-1,4-linkage and moving 7 residues to synthesize alpha-1,6-linkage

26
Q

What is the key regulatory enzyme of glycogen synthesis?

A

Glycogen synthase

27
Q

What is the active form of glycogen synthase?

A

Synthase a

28
Q

What is the inactive form of glycogen synthase?

A

Synthase b

29
Q

What state does synthase a favor?

A

R

30
Q

What state does synthase b favor?

A

T

31
Q

What does phosphorylation do to synthase b?

A

Inactivates it

32
Q

What converts synthase a to synthase b?

A

Glycogen synthase kinase

33
Q

What inactivates glycogen synthase kinase?

A

Insulin through phosphorylation

34
Q

What converts synthase b to synthase a?

A

PP1

35
Q

What happens to phosphorylase when exercising or fasting?

A

a form and active, phosphorylated
glycogen degradation

36
Q

What happens to glycogen synthase when exercising or fasting?

A

b form and inactive, phosphorylated

37
Q

What enzymes are active when exercising or fasting?

A

Protein Kinase A
Phosphorylase Kinase
Phosphorylase a
Glycogen synthase kinase

38
Q

What enzymes are inactive when exercising or fasting?

A

Glycogen synthase b

39
Q

What happens to phosphorylase when resting or after meal?

A

b from and inactive, dephosphorylated

40
Q

What happens to glycogen synthase when resting or after meal?

A

a form and active, dephosphorylated
Glycogen synthesis

41
Q

What happens to glycogen synthase when resting or after meal?

A

a form and active, dephosphorylated
Glycogen synthesis

42
Q

What enzymes are inactive when resting or after a meal?

A

Phosphorylase b
Phosphorylase kinase

43
Q

What enzymes are active when resting or after a meal?

A

Glycogen synthase a

44
Q

Are enzymes phosphorylated or dephosphorylated during glycogen degradation?

A

Phosphorylated

Biochem Exam 4 (7 decks)

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