41. Glycogen Metabolism

Question 1

major storage cacrbohydrate in animals

Answer 1

glycogen

Question 2

______ gram of glycogen

stored in muscle and liver

Answer 2

500 grams

Question 3

where does glycogenesis occur

Answer 3

• liver and muscle

* cytosol

Question 4

rate limiting step of glycogenesis

Answer 4

elongation of glycogen chains
alpha (1,4) glycosidic bonds
enzyme: glycogen synthase

Question 5

protein that serves as a primer for glycogen synthesis when glycogen is completely depleted

Answer 5

glycogenin

Question 6

synthesis of UDP-glucose requires this enzymes

Answer 6

phosphoglucomutase

UDP-glucose pyrophosphorylase

Question 7

source of all glucosyl residues that are added to glycogen molecule

Answer 7

UDP-glucose

Question 8

elongation of glycogen chains

enzyme

Answer 8

glycogen synthase

Question 9

rate limiting step of glycogenesis

Answer 9

elongation of glycogen chain
•glycogen synthase
•bonds formed at non-reducing end (C4)

Question 10

formation of branches in glycogen

enzyme ?

Answer 10

branching enzyme

•amylo alpha (1–>4) –> alpha (1–>6) transglucosidase

Question 11

forms alpha (1–>6) bonds by transferring 5-8 glucosyl residues

Answer 11

branching enzyme

•amylo alpha (1–>4) –> alpha (1–>6) transglucosidase

Question 12

forms alpha (1–>4) bonds between glucose residues

Answer 12

glycogen synthase

Question 13

for mobilizing stored glycogen

Answer 13

glycogenolysis

Question 14

where does glycogenolysis occur

Answer 14

• liver, muscle

* cytosol

Question 15

what is the substrate of glycogenolysis

Answer 15

glycogen

Question 16

what are products of glycogenolysis

Answer 16

• glucose - liver

* glucose-6-phosphate - muscle

Question 17

rate limiting step of glycogenolysis

Answer 17

shortening of glycogen chains
enzyme : glycogen phosphorylase
- cleavage of alpha (1–>4) bonds
between glucosyl residues at non reducing ends of glycogen chains

co-enzyme: pyridoxal phosphate

Question 18

when does shortening of glycogen chain stop

Answer 18

when 4 glucosyl units remain (limit dextrin)

Question 19

removal of branches of glycogen

enzyme?

Answer 19

debranching enzyme :
•alpha (1–>4) -> alpha (1–>4) glucantransferae
•amylo-alpha (1–>6) glucosidase

• cleaves alpha (1–>4) and alpha (1–>6) bonds

Question 20

debranchign enzyme yields free glucose from cleavage of ___ bond

Answer 20

alpha (1–>6) bonds

Question 21

conversion of glucose-1-P to glucose -6-P or glucose

enzyme

Answer 21

phosphoglucomutase
and when present
glucose-6-phosphatase

Question 22

lysosomal degradation of glycogen

Answer 22

alpha (1–>4) glucosidase (acid maltase)

Question 23

degrades 1-3% of glycogen

Answer 23

lysosomal degradation of glycogen

Question 24

deficiency of this enzyme leads to Pompe disease

Answer 24

alpha (1–>4) glucosidase (acid maltase)

Question 25

glycogen synthase

pathway

Answer 25

glycogenesis

Question 26

glycogen phosphorylase

pathway

Answer 26

glycogenolysis

Question 27

Presence of glucose-6-P
effect on
glycogen synthase

Answer 27

activated

Question 28

Presence of glucose-6-P
effect on
glycogen phosphorylase

Answer 28

inhibited

Question 29

Presence of ATP
effect on
glycogen phosphorylase

Answer 29

inhibited

Question 30

Presence of calcium (muscle)
effect on
glycogen phosphorylase

Answer 30

activated

Question 31

Presence of glucagon and epinephrine
on
glycogen synthase

Answer 31

inhibited

Question 32

Presence of insulin
effect on
glycogen synthase

Answer 32

activated

Question 33

phosphorylation

effect on
glycogen synthase

Answer 33

inactive

Question 34

Presence of glucagon and epinephrine

effect on
glycogen phosphorylase

Answer 34

activated

Question 35

Presence of INSULIN
effect on
glycogen phosphorylase

Answer 35

Inhibited

Question 36

PHOSPHORYLATION
effect on
glycogen phosphorylase

Answer 36

Active

Question 37

group of inherited disorders characterized by deposition of abnormal type or quantity of glycogen in tissues

Answer 37

glycogen storage diseases

Question 38

glucose-6-phosphatase deficiency

Answer 38

Type Ia

Von Gierke disease

Question 39

lysosomal acid maltase deficiency

Answer 39

Type II Pompe disease

Question 40

debranching enzyme deficiency

Answer 40

Type III a cori disease

Question 41

branching enzyme deficiency

Answer 41

type IV Andersen disease

Question 42

muscle phosphorylase deficiency

Answer 42

Type V McArdle syndrome

Question 43

liver phosphorylase deficiency

Answer 43

Type VI

Hers disease

Question 44

• ÎÎ glycogen in liver and renal tubule cells
• hypoglycemia
• lactic acidosis
• ketosis
• hyperlipidemia

Answer 44

Von Gierke disease

Question 45

• ÎÎ glycogen in lysosomes
• Juvenile onset - hypotonia, death, heart failure
• adult onset - muscle dystrophy

Answer 45

Pompe disease

Question 46

• fasting hypoglycemia , hepatomegaly in infancy
• ÎÎ limit dextrin
• muscle weakness

Answer 46

Type IIIa cori disease

Question 47

• hepatosplenomegaly
• ÎÎ polysaccharide with few branch points
• death from heart or liver failure before age 5

Answer 47

Anderrsen disease

Question 48

• poor exercise tolerance
• muscle cramps and myoglobinuria but no alctic acidosis
• ÎÎ muscle glycogen

Answer 48

McArdle syndroe

Question 49

• Hepatomegaly

* mild hypoglycemia

Answer 49

Hers disease