Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BMS07 > Glucose & Glycogen Metabolism > Flashcards

Glucose & Glycogen Metabolism Flashcards

1
Q

How much glucose is present in the body and where?

A

10g in plasma

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

How much glycogen is present in the body and where?

A

400g in tissue stores

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

Why is there so little glucose in the body?

A

Immediate energy source

Osmotically active so stored as glycogen

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

What bonds are present between glucose monomers in a glycogen molecule?

A

1,4-glycosidic bonds

1,6-glycosidic bonds at branches

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

How much glycogen is stored in the liver?

A

100-120g

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

What is the role of glycogen in the liver?

A

(Liver is sensitive to blood glucose concentration)

Acts to maintain blood glucose under influence of insulin and glucagon

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

What is the role of glycogen in muscles?

A

Fuel for muscle contraction (used locally)

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

What is muscle glycogen sensitive to? (5)

A

Needs of tissue

Calcium

Adrenaline

AMP

ATP

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

Why is glycogen not converted all the way to glucose in muscle tissue?

A

Glucose-6-phosphate can enter glycolysis pathway directly

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

What enzyme catalyses glycogen synthesis?

A

Glycogen synthase/synthetase

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

What enzyme catalyses glycogen breakdown?

A

Glycogen phosphorylase

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

What are the final products of glycogen degradation in the liver and muscles?

A

Liver: glucose

Muscle: glucose-6-phosphate

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

Why are there two separate enzymes used to catalyse the synthesis/breakdown of glycogen?

A

Prevent a futile cycle

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

What are the two general steps of glycogen synthesis?

A
  1. Activation of glucose

2. Glycogen synthase reaction

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

What occurs during the first step of glycogen synthesis?

A

Hexokinase/glucokinase phosphorylates glucose using ATP to form glucose-6-phosphate

Phosphoglucomutase converts glucose-6-phosphate to glucose-1-phosphate

UDP glucose pyrophorylase converts glucose-1-phosphate to UDP glucose using UTP (forms pyrophosphate/PPi)

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

What occurs during the second step of glycogen synthesis?

A

UDP glucose and glycogen primer molecule joined by 1,4-glycosidic bond by glycogen synthase (forms glycogen and UDP)

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

Describe the process of glycogen breakdown

A

Glycogen phosphorylase uses a phosphate to break glycogen into glycogen (n-1) and glucose-1-phosphate

Phosphoglucomutase converts glucose-1-phosphate to glucose-6-phosphate

Glucose-6-phosphatase catalyses hydrolysis of glucose-6-phosphate to glucose and Pi

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

Where is glucokinase found?

A

Liver

19
Q

Where is hexokinase found?

A

All tissues except liver

20
Q

Where is glucose-6-phosphatase found?

A

Liver and kidney

21
Q

Where does glycolysis occur?

A

Cytosol of all cells in all organisms

22
Q

What is the purpose of glycolysis? (2)

A

Synthesise ATP using glucose as fuel

Forms intermediates for fat or amino acid synthesis

23
Q

Where can glucose be sourced from? (3)

A

Sugars and starch from diet

Glycogen stores in liver

Recycling from lactic acid, amino acids or glycerol

24
Q

How many reactions make up the glycolysis pathway?

A

10

25
Q

What are the four general stages of glycolysis?

A
  1. Activation using ATP
  2. Splitting of 6C sugar
  3. Oxidation (removal of 2H)
  4. Synthesis of ATP
26
Q

Describe the activation stage of glycolysis

A
  1. Hexo/glucokinase uses ATP to phosphorylate D-glucose to glucose-6-phosphate
  2. Phosphohexose isomerase converts glucose-6-phosphate to fructose-6-phosphate
  3. Phosphofructokinase uses ATP to phosphorylate fructose-6-phosphate to fructose-1,6-bisphosphate
27
Q

Describe the splitting stage of glycolysis

A
  1. Aldolase catalyses the splitting of fructose-1,6-bisphosphate into glyceraldehyde 3-phosphate and dihydroxyacetone phosphate
  2. Triose phosphate isomerase converts dihydroxyacetone phosphate to glyceraldehyde 3-phosphate
28
Q

Describe the oxidation stage of glycolysis

A
  1. Glycerate 3-phosphate dehydrogenase converts glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate by adding a Pi

NAD+ is reduced

29
Q

Describe the ATP synthesis stage of glycolysis

A
  1. Phosphoglycerate kinase converts 1,3-bisphosphoglycerate to 3-phosphoglycerate; ATP formed
  2. Phosphoglycerate mutase converts 3-phosphoglycerate to 2-phosphoglycerate
  3. Enolase dehydrates 2-phosphoglycerate to phosphoenol pyruvate
  4. Pyruvate kinase converts phosphoenolpyruvate to pyruvate; ATP formed
30
Q

What inhibits enolase?

A

Fluoride ions

31
Q

What are the three irreversible stages of glycolysis and their enzymes?

A

First (hexo/glucokinase)

Third (phosphofructokinase)

Last (pyruvate kinase)

32
Q

What is the net yield of ATP from glycolysis using one glucose?

A

2 ATP

33
Q

What is the reaction of anaerobic respiration?

A

Pyruvate + NADH + H+ –> lactate + NAD+

34
Q

What enzyme catalyses anaerobic respiration?

A

Lactate dehydrogenase

35
Q

Where is lactate converted back to pyruvate?

A

Liver

36
Q

What happens to pyruvate in micro-organisms?

A

Converted to ethanol (anaerobic respiration)

37
Q

What happens to pyruvate in aerobic conditions?

A

Converted to acetyl CoA then used in TCA cycle and oxidative phosphorylation to form carbon dioxide and water

38
Q

What happens to pyruvate in humans in anaerobic conditions?

A

Converted to lactate

39
Q

How does allosteric control of glycogen metabolism work?

A

Glucagon or adrenaline bind and activate cell surface receptor which activates an internal signalling pathway

Protein kinase is activated

Glycogen phosphorylase is phosphorylated = activated

Glycogen synthase phosphorylated = deactivated

40
Q

Which allosteric regulators affect phosphofructokinase?

A

ATP and citrate = allosteric repressors/inhibitors

AMP = allosteric activator

41
Q

What is the function of glycolysis in skeletal muscle? (2)

A

ATP production during intense exercise (lack of oxygen)

Produce pyruvate to form acetyl CoA for aerobic respiration

42
Q

What is the function of glycolysis in red blood cells?

A

Only pathway for ATP production (no mitochondria)

43
Q

What is the function of glycolysis in the brain?

A

Major source of ATP (cannot use fat)

BMS07 (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions