Chapter 16: Regulation of Glycogen Metabolism Flashcards
1
Q
Insulin produced in the fed state leads to
A
- Anabolism
- Glycolytic flux/glycogen synthesis
- Works by dephosphorylation
2
Q
Glucagon produced in the fasting state leads to
A
- Catabolism
- Glycogen break down
3
Q
Glycogen
A
- The storage form of glucose
4
Q
Glucose residues linked by
A
- Alpha-1,4-glycosidic bonds
- Alpha-1,6-glycosidic bond every 10 residues
5
Q
In muscle, glycogen serves as
A
- An energy store for the synthesis of ATP
6
Q
In the liver, glycogen functions as
A
- A glucose reserve to maintain blood sugar levels
7
Q
Glycogen stores are depleted after
A
- After 2 days when when gluconeogenesis is the major source of blood glucose
8
Q
GLUT 4
A
- Glucose transporter present on muscle cell
- Sensitive to insulin
- In the cytoplasm > insulin stimulation gets it to membrane
9
Q
Glycogen phosphorylase cleaves
A
- Only alpha-1,4-glycosidic bonds in glycogen
10
Q
Two interconvertible forms of glycogen phosphorylase
A
- Glycogen phosphorylase A
- Glycogen phosphorylase B
11
Q
Glycogen phosphorylase A is the
A
- More active form
12
Q
Glycogen phosphorylase B is the
A
- Less active form
- Requires AMP
13
Q
Glycogen phosphorylase B is converted to A by
A
- Phosphorylation
- Glycogen phosphorylase kinase (Ca+ dependent)
14
Q
Glycogen phosphorylase A is converted to B by
A
- Protein phosphatase I
15
Q
3 components involved with regulation of glycogen degradation in muscle
A
- AMP
- ATP
- G-6-P
16
Q
Cleavage of alpha-1,4-glycosidic bonds in glycogen requires
A
- Pyridoxical phosphate prosthetic group
17
Q
Glycogen phosphorylase is controlled by
A
- Reversible phosphorylation
18
Q
Glucose shifts T to R equilibrium toward
A
- T state
19
Q
Epinephrine promotes
A
- Glycogen degradation in muscle
20
Q
Hormones regulation mechanism
A
- Covalent modification
21
Q
Main source of epinephrine in glycogen degradation in muscle
A
- Adrenal medulla
22
Q
Epinephrine binding site
A
- B-adrenergic receptor on muscle cells
23
Q
Binding of epinephrine to B-adrenergic receptors on muscle cells activates
A
- Adenylate cyclase
24
Q
cAMP stimulates
A
- Pr K A
25
Phosphorylation stimulates glycogen phosphorylase kinase that ...
- Phosphorylates glycogen phosphorylase b > a activation
26
Glycogen degradation process
- Glycogen degradation > G-1-P > ATP formation (3)
27
Regulation of glycogen synthesis in muscle occurs via
- Covalent modification
28
Glycogen synthase is inactivated by
- Phosphorylation
29
Inactivation of glycogen synthase causes
- cAMP/Pr K A
| - Turning off glycogenesis
30
Less active glycogen synthase b requires
- Glucose-6-Phosphate
31
Glycogen synthase is activated by
- Dephosphorylation
32
Insulin activates a protein phosphatase I, favoring
- Dephosphorylation of glycogen synthase
33
Activation of glycogen synthase turns on
- Glycogenesis
| - Adds glucose units to non-reducing end of polymer
34
Coordinate control of glycogen metabolism occurs via
- Hormone-mediated cascade
35
Protein Kinase A phosphorylates BOTH
- Glycogen synthase
| - Glycogen phosphorylase
36
PP1 removes phosphate groups, favoring
- Glycogen synthesis
37
Pr K A phosphorylates and activates an inhibitor of PP1, making
- Making PP1 less active
| - Favoring Glycogenolysis
38
Glycogen in the liver exists as
- Granules
39
Glycogen stores increase after
- Eating (insulin)
40
Liver glycogen metabolism maintains
- Blood sugar level
| - Liver glucose-6-phosphatase also important
41
Primary hormone involved in liver glycogen metabolism
- Glucagon
| - Similar mechanism to epinephrine
42
Liver glycogen phosphorylase B is NOT activated by
- AMP (muscle enzyme is)
43
Glycogen phosphorylase A is inactivated by
- Glucose
44
Insulin favors
- Glycogen synthesis in the liver
45
Glucose favors
- Glycogen synthesis
46
Glycogen provides blood glucose for
- The first hours in post absorptive phase
47
Glycogen stores are depleted after
- 2 days when gluconeogenesis is the major source of blood glucose
48
Nibbler's Disease
- Will require 24 hour period of feeding
- Can’t use glucose
- Can’t cope with periods of starvation
49
Glycogen synthase and glycogen phosphorylase is controlled via
- Coordinate control
50
Glycogen metabolism is generally regulated/determined by
- Levels of cellular metabolites
| - Hormone-mediated mechanisms
51
Glucagon and epinephrine hormones mediate phosphorylation of key regulatory enzymes via
- cAMP-dependent mechanisms
52
Glycogen phosphorylase is activated by
- Phosphorylation
53
Glycogen synthase is inhibited by
- Phosphorylation
54
Von Gierke's Disease is caused by a lack of
- Liver glucose-6-phosphatase
55
Von Gierke's Disease consequences
- Patients are unable to produce free glucose from glycogen
| - Glucose-6-phosphate accumulates
56
McArdle's Disease is caused by
- A defective muscle glycogen phosphorylase
| - Makes prolonged exercise painful
57
Insulin favors biosynthesis in both
- Both liver and muscle tissues
58
Epinephrine works on the
- Muscle cell
59
Glucagon works on the
- Hepatocyte
60
Glycogen synthase in the active (a) form is
- Dephosphorylated
61
Glycogen synthase in the inactive (b) form is
- Phosphorylated
62
Glycogen phosphorylase in the active (a) form is
- Phosphorylated
63
Glycogen phosphorylase in the inactive (b) form is
- Dephosphorylated
64
Phosphorylase b active form
- R form
65
Phosphorylase b inactive form
- T form
66
Phosphorylase a inactive form
- T form
67
Phosphorylase a active form
- R form
68
Control of glycogen phosphorylase activity by reversible phosphorylation is catalyzed by
- Glycogen phosphorylase kinase
