BGM1002/L25 Glycogen Metabolism Flashcards

(48 cards)

1
Q

How many residues are between each branch point in glycogen?

A

10

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Why is glucose converted to glycogen? (2)

A

Renal loss
Osmotic pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why is glycogen branched?

A

Facilitates fast mobilisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where are the 2 main sites of glycogen storage?

A

Liver and muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Which is the largest glycogen store in the body?

A

Muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What percentage weight of muscle is glycogen?

A

2%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is glucose released as in muscle?

A

Glucose-6-phosphate (just for muscle)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Why can’t glucose escape muscle cells?

A

Muscle lacks the enzyme to remove final phosphate group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What percentage by weight of glycogen is the liver?

A

10%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How many kJ/g is glycogen?

A

17

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How many kJ/g is fat?

A

37kJ/g

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Why does the body favour fat as an energy source?

A

It stores energy more efficiently

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How many steps are there to glycogenesis?

A

3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Name the 4 main molecules in glycogenesis.

A

Glucose-6-phosphate
Glucose-1-phosphate
UDP-glucose
Glycogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Name step 1 of glycogenesis.

A

Diversion
Glucose-6-phosphate -> glucose-1-phosphate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What enzyme is involved in diversion (step 1) of glycogenesis?

A

Phosphoglucomutase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Name step 2 of glycogenesis.

A

Activation
Glucose-1-phosphate -> UDP-glucose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What enzyme is involved in activation (step 2) of glycogenesis?

A

UDP-glucose pyrophosphorylase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What enzyme separates the 2 phosphate groups formed in step 2 of glycogenesis?

A

Inorganic pyrophosphorylase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Name step 3 of glycogenesis.

A

Polymerisation
UDP-glucose -> glycogen

21
Q

What enzyme is involved in polymerisation (step 3) of glycogenesis?

A

Glycogen synthase

22
Q

Name step 4 of glycogenesis.

23
Q

What is the primer required for glycogen synthase?

24
Q

When does glycogenesis usually occur?

A

Post-prandially
Between meals

25
Name the 2 steps of glycogenolysis.
Erosion of chain ends Debranching
26
What enzyme is required for step 1 of glycogenolysis (erosion of chain ends)?
Glycogen phosphorylase
27
Which step is the rate-limiting step of glycogenolysis?
Step 1: erosion of chain ends
28
How is the activity of glycogen phosphorylase regulated?
Controlled by phosphorylation
29
Where does glycogen phosphorylase stop acting?
4th glucose-1-phosphate
30
What enzymes are involved in step 2 of glycogenolysis? (2)
Alpha-(1->4)-transglycosylase Alpha-(1->6)-glucosidase
31
What is the role of alpha-(1->4)-transglycosylase?
Transfer of 3/4 glucose units to end of the chain
32
What is the role of alpha-(1->6)-glucosidase?
Breaking off the last remaining glucose unit from the side chain
33
What is step 3 of glycogenolysis?
Recovery Glucose-1-phosphate -> glucose-6-phosphate
34
What enzyme is involved in step 3 of glycogenolysis?
Phosphoglucomutase
35
What is step 4 of glycogenolysis?
Release for glycolysis or to the liver
36
What enzyme converts glucose-6-phosphate to glucose?
Glucose-6-phosphatase
37
Give 4 symptoms of glycogen storage diseases (GSD).
Muscle cramp Muscle weakness General tiredness Hypoglycaemia Hepatomegally (liver enlargement)
38
What occurs in liver glycogen synthase deficiency?
Glycogen can't be polymerised Glucose-1-phosphate remains in liver
39
Give 2 symptoms of liver glycogen synthase deficiency.
Hyperglycaemia Hypoglycaemia
40
What occurs in Von Gurke's Disease (glucose-6-phosphate deficiency)?
Final phosphate can't be converted into glucose Glucose can't be deposited back into blood
41
Give 2 symptoms of Von Gurke's disease.
Hypoglycaemia Hepatomegally
42
What occurs in Cori's Disease (amylo-1,6-glucosidase deficiency)?
Second active site of debrancher Glycolysis blocked at branches
43
Give 2 symptoms of Cori's Disease.
Hepatomegally Hypoglycaemia
44
What occurs in Andersen's Disease (amylo-(1,4->1,6)-glucosidase defiency)?
Brancher enzyme Glucose release insufficiently fast
45
Give 2 symptoms of Andersen's Disease.
Hepatomegally Hypoglycaemia Poor prognosis
46
What occurs in McArdle's Disease (muscle phosphorylase deficiency)?
Muscle isoenzyme releases terminal sugars Muscle requirements not met during exercise
47
Give a symptom of McArdle's Disease.
Muscle cramps/weakness
48
How can glycogen storage diseases be identified?
Muscle biopsy