Metabolism Of Glycogen

Question 1

Major storage carbohydrate in animals

Answer 1

Glycogen

Question 2

Branched polymer of alpha-D-glucose

Answer 2

Glycogen

Question 3

Where does glycogen mainly occur

Answer 3

Liver and muscle; modest amounts in brain

Question 4

Which has a higher glycogen content, liver or muscle?

If so, what supplies three-quarters of the total body glycogen?

Answer 4

Liver has higher glycogen content but because muscle mass is greater than liver, three quarters of total body glycogen is in muscle

Question 5

Provides a readily available source of glucose-1-phosphate for glycolysis within muscle

Answer 5

Muscle glycogen

Question 6

Functions as a reserve to maintain blood glucose concentration in the fasting state

Answer 6

Liver glycogen

Question 7

Liver concentration of glycogen after a meal and during fasting

Answer 7

450 mmol/L

200 mmol/L

Question 8

Liver glycogen is almost totally depleted after how many hours?

Answer 8

12-18 hours

Question 9

Does muscle glycogen directly yield glucose?

Answer 9

No because they lack G-6-Pase

Question 10

Pyruvate formed from glycolysis in muscle can undergo transamination to _____, which is exported from muscle and is used for gluconeogenesis in the _____

Answer 10

Alanine

Liver

Question 11

Glycogen storage diseases

Answer 11

Group of inherited disorders characterized by deficient mobilization of glycogen or deposition of abnormal forms of glycogen

Question 12

Provides a large number of sites for glycogenolysis

Answer 12

Highly branched structure of glycogen

Question 13

What catalyzes phosphorylation of glucose to glucose-1-phosphate in muscle and liver

Answer 13

Hexokinase

Glucokinase

Question 14

What isomerizes G-6-P to G-1-P

Answer 14

Phosphoglucomutase

Question 15

G-1-P reacts with UTP to form ——

This reaction is catalyzed by

Answer 15

UDPGlc (uridine diphosphate glucose) and pyrophosphate

UDPGlc pyrophosphorylase

Question 16

Catalyzes hydrolysis of pyrophosphatase to 2 x to phosphate

Answer 16

Pyrophosphatase

Question 17

T/F

UDPGlc phosphorylase has a low Km for G-1-P and is present in large amounts.

Answer 17

True

Question 18

Not a regulatory step in glycogen synthesis

Answer 18

UDPGlc pyrophosphorylase

Question 19

Percentage of tissue weight

Answer 19

Liver - 5
Muscle - 0.7
Extracellular glucose - 0.1

Question 20

Tissue weight

Answer 20

Liver - 1.8kg
Muscle - 35kg
Extracellular glucose -10L

Question 21

Body content

Answer 21

Liver - 90
Muscle - 245
Extracellular glucose - 10

Question 22

Initial steps of glycogen synthesis involves what protein

Answer 22

Glycogenin

Question 23

A protein that is glucosylated on a specific tyrosine residue by UDPGlc

Answer 23

Glycogenin

Question 24

Catalyzes the transfer of 7 glucose residues from UDPGlc in 1->4 linkage to form glycogen primer

Answer 24

Glycogenin

Question 25

Dies glycogenin remain at the core of glycogen granule?

Answer 25

Yes

Question 26

Catalyzes the formation of a glycoside bond between C-1 of the glucose UDPGlc and C-4 of terminal glucose residue of glycogen, liberating UDP

Answer 26

Glycogen synthase

Question 27

Where does the addition of a glucose residue to a primer occur?

Answer 27

Nonreducing outer end of molecule

Question 28

Transfers part of 1->4 chain to 1->6 linkage when a growing chain is at least 11 glucose residues long

Answer 28

Branching enzyme

Question 29

Define branch point

Answer 29

Pg. 178 of pdf

Question 30

T/F Glycogenolysis is the reverse of glycogenesis

Answer 30

False

Question 31

What does glycogen phosphorylase catalyze?

Answer 31

Rate-limiting step in glycogenolysis —phosphorolytic cleavage of 1->4 linkages of glycogen to yield G-1-P

Question 32

Glycogen phosphorylase have different isoenzymes in liver muscle and brain

Answer 32

True

Question 33

Required coenzyme of glycogen phosphorylase

Answer 33

Pyroxidal phosphate