Glycogen

Question 1

How can we obtain glucose for the body?

Answer 1

The diet
Degradation of glycogen
Gluconeogenesis

Question 2

Which source of glucose is faster: glycogen synthesis or gluconeogenesis?

Answer 2

Glycogen Synthesis

Question 3

Where is most glycogen found and stored?

Answer 3

In the liver or muscle

Question 4

From what source is the glycogen provided for blood glucose?

Answer 4

Liver

Question 5

How much glycogen is found in muscle?

Answer 5

400 g

Question 6

How much glycogen is found in the liver?

Answer 6

100 g

Question 7

List three properties of Glycogen

Answer 7

Branched polysacharide
Alpha (1-4) glycosidic bonds
Branches of Alpha (1-6) glycosidic bonds

Question 8

Where and how in the cell is glycogen stored?

Answer 8

As small granules in the cytoplasm of cells.

Question 9

What will happen to glycogen stores in the liver while eating?

Answer 9

Increase

Question 10

Glycogen is synthesized from what molecule and what does it require?

Answer 10

Alpha-D-Glucose and requires ATP and Uridine Triphosphate (UTP)

Question 11

One of the first steps is the conversion of Glucose-6-Phosphate to ___________ by the enzyme ___________.

Answer 11

Glucose-1-Phosphate by the enzyme Phosphoglucomutase

Question 12

What enzymes catalyzes the conversion of Glucose-1-Phosphate to UDP-glucose?

Answer 12

UDP-glucose pyrophosphoryase

Question 13

What compound is the source of ALL the glucose residues in the synthesis of glycogen?

Answer 13

UDP-glucose

Question 14

What enzyme makes the chains of alpha(1-4) glycosidic linkages in glycogen? What can it not use?

Answer 14

Glycogen synthase - cannot use free glucose to act as an acceptor molecule for UDP-glucose.

Question 15

What protein will add glucose onto itself? What is this process called?

Answer 15

Glycogenin - autoglucosylation

Question 16

What will glucose use to attach to the glycosylated glycogen?

Answer 16

UDP-glucose

Question 17

When can glycogen synthase start to build the glycogen chain?

Answer 17

Once a few monomers of glucose are linked forming a primer.

Question 18

How is elongation of the glycogen chain happening?

Answer 18

Glucose-UDP is transferred to the non-reducing end of the growing chain.

Question 19

Where will the new glycosidic bond be formed? What is the linkage made by?

Answer 19

The anomeric hydroxy group of the UDP-glucose and carbon 4 of the accepting glucose molecule. Made by glycogen synthase.

Question 20

The released UDP can be phosphorylated by what energy rich compound?

Answer 20

ATP

Question 21

What enzyme is responsible for this to occur?

Answer 21

Nucleoside Diphosphate Kinase

Question 22

What is amylose?

Answer 22

Unbranched glucose linked by Alpha (1-4) linkages found in plants.

Question 23

The branching of glycogen occurs at every __ residues of glucose?

Answer 23

8

Question 24

Branching increases the number of non-reducing ends to which new glucose can be added. This greatly speeds up what?

Answer 24

The synthesis of glucose.

Question 25

What is the name of the branching enzyme?

Answer 25

Amylo-alpha-(1-4) - alpha-(1-6) transglucosidase

Question 26

How does this branching enzyme work?

Answer 26

Cleaves off 6-8 glucosyl residues breaking a alpha(1-4) bond in the process.

Question 27

What happens to these glucose residues after being broken off?

Answer 27

They are then attached to a non-terminal glucose residue by a alpha-(1-6) linkage.

Question 28

Is the breakdown of glycogen the reversal of the making of glycogen?

Answer 28

No

Question 29

When glycogen is broken down the end products are...

Answer 29

Glucose-1-phosphate and some free glucose

Question 30

Glucose-1-phosphate is obtained from the breaking down of what type of bonds?

Answer 30

Alpha(1-4) glycosidic linkages.

Question 31

How is the free glucose obtained?

Answer 31

The breaking down of each alpha(1-6) glycosidic bond.

Question 32

What enzyme will cleave the alpha(1-4) bonds from the non-reducing end?

Answer 32

Glycogen Phosphorylase

Question 33

How many glucose units will remain on each chain after the chain is cleaved by glycogen phosphorylase?

Answer 33

4

Question 34

What does Glycogen phosphorylase require to function?

Answer 34

The co-enzyme pyridoxal phosphate which is Vit B6

Question 35

What is the name of the structure that remains after the glycogen is cleaved?

Answer 35

Limit Dextrin and it cannot be degraded further by glycogen phosphorylase.

Question 36

How many enzymatic reactions are required to remove the branches?

Answer 36

2

Question 37

The first enzymatic reaction to remove the branches uses what enzyme? How any of the four glucose residues will it remove?

Answer 37

oligo-alpha(1-4) - alpha (1-4) glucan transferase. Will remove 3 of the 4 residues

Question 38

Where do the 3 residues get transferred to on another glycogen molecule?

Answer 38

To the nonreducing end of another chain lengthening that chain.

Question 39

The single glucose that was not cleaved off by the transferase will be removed by what enzyme? What will it release?

Answer 39

amylo-alpha (1-6) glucosidase. Will release free glucose.

Question 40

Where in the cell is glucose-1-phosphate converted to glucose-6-phosphate?

Answer 40

Phosphoglucose mutase.

Question 41

The conversion of glucose-1-phosphate to glucose-6 takes place through what intermediate?

Answer 41

glucose 1,6 bisphosphate

Question 42

In the liver, glucose-6 phosphate is transported where by glucose-6-phosphate translocase?

Answer 42

The endoplasmic reticulum

Question 43

In the endoplasmic reticulum glucose-6-phosphate is converted to glucose by what enzyme?

Answer 43

Glucose-6-phosphatase

Question 44

In muscle tissue, where does glucose-6-phosphate enter and why?

Answer 44

Glycolysis as muscles lack glucose-6-phosphatase

Question 45

What percent of glycogen is broker down in the lysosomes?

Answer 45

1-3%

Question 46

What is the enzyme called that breaks glycogen down in the lysosomes?

Answer 46

acid alpha(1-4) glucosidase

Question 47

A deficiency in this enzyme will cause what effect?

Answer 47

An accumulation of glycogen in cavuoles in the lysosomes resulting in muscle weakness.

Question 48

About 1 in how many individuals will be born with a glycogen storage disease.

Answer 48

40 000

Question 49

GSD 1 is what condition and what enzyme is flawed?

Answer 49

Von Gierkes Disease - glucose-6-phosphatase (cannot convert glucose-6-phosphate to glucose)

Question 50

Pompe's Disease is GSD __ and impacts what specific enzyme?

Answer 50

II - acid alpha-glucosidase (causes an accumulation of glycogen in vacuoles within lysosomes = muscle weakness)

Question 51

GSD IV aka? enzyme?

Answer 51

Andersen Disease - amylo 1-4, 1-6 transglucosidase

Question 52

Pompe's disease can also be called?

Answer 52

Acid Maltase Deficiency

Question 53

The accumulation of glycogen in the tissue with Pompe's Disease will give what appearance?

Answer 53

Appearance of pseudo-hypertrophic muscles.

Question 54

Pompe's disease will affect what structures and cause what symptoms in the body?

Answer 54

The diaphragm, the heart and tongue are enlarged, lordosis, kyphosis and death is usually by heart failure

Question 55

Andersen's is described as a bad Cori's disease and is due to a deficiency in what enzyme?

Answer 55

Glycogen branching enzyme amylo1-4, 1-6 transglucosidase.

Question 56

This deficiency will affect glycogen how? What will the clinical symptoms be?

Answer 56

Accumulation of abnormal glycogen with long outer branches. Clinical features are muscle hypotonia and Cirrhosis - death from liver disease.