Carbohydrate Metabolism Flashcards Preview

Physiology > Carbohydrate Metabolism > Flashcards

Flashcards in Carbohydrate Metabolism Deck (122):
1

What is metabolised in the intestine

Fats to Fatty Acids
Complex Carbohydrates to Monosaccharides
Proteins to Amino Acids

2

What metabolic processes happen in the cell cytoplasm

Conversion between pyruvate and lactate

3

What metabolic processes happen in the mitochondra

Formation of Acetyl Co-A
TCA Cycle
Most other metabolic activities

4

What are the energy carrying molecules

ATP, ADP, AMP
UTP, GTP, CTP, TTP

5

What is used for ATP storage

Creatine Phosphate

6

What are the electron carriers

NAD+, FAD, FMN, NADP+

7

What are the acyl group carriers

Co-ASH
Becomes Co-A when carrying acyl group

8

What does Glycogenesis convert

Glucose-6-phosphate to Glycogen

9

What does Glycogenolysis convert

Glycogen to Glucose-6-phosphate

10

What does Gluconeogenesis convert

Pyruvate to Glycose-6-phosphate

11

What does glycolysis convert

Glycose-6-phosphate to pyruvate

12

What does lipogenesis convert

Fatty Acids to Triacyglycerols

13

What does lipolysis convert

Triacyglycerols to Fatty Acids

14

What does FA synthesis convert

Acetyl Co-A to Fatty Acids

15

What does beta-oxidation convert

Fatty Acids to Acetyl Co-A

16

What are the consequences of eating dietry fibre

Adds bulk to faeces
Retains water in GIT
Speeds intestinal transit
Increases intestinal flora
Prevents diverticulitis and haemorrhoids
Slows digestion and absorption

17

How many carbons are there in monosaccharides

3-9

18

What are the types of hexoses

Glucose, Fructose, Galactose

19

What is the difference between wet monosaccharides and dry monosaccharides in structure

Wet - ring shape
Dry - chain structure

20

What are the types of pentoses

Ribose, Deoxyribose

21

What are disaccharides? Give some examples

Sucrose, Maltose, Lactose
2 monosaccharide subunits

22

What is sucrose made up of

Fructose and Glucose

23

What is maltose made up of

2 Glucose sugars

24

What is Lactose made up of

Glucose and Galactose

25

What are the three groups of polysaccharides

Starch
Glycogen
Cellulose

26

What are the types of starch

Amylose --- alpha-1,4 bonds
Amylopectin --- alpha-1,4 bonds and alpha-1,6 bonds

27

What is the structure of glycogen

alpha-1,4 bonds and alpha-1,6 bonds (more than in starch)

28

What is the structure of cellulose

beta-1,4 bonds

29

What is the membrane protein that absorbs maltooligosaccharides

Glucoamylase

30

What is the membrane protein that absorbs glucose

Glucose carrier

31

What is the membrane protein that absorbs alpha-limit dextrins

alpha-Dextrinase

32

What is the membrane protein that absorbs sucrose

Sucrase

33

What is the membrane protein that absorbs fructose

Fructose carrier

34

What is the membrane protein that absorbs gluucose

Glucose carrier

35

What is the membrane protein that absorbs lactose

Lactase

36

What is lactose intolerance caused by

Deficiency of lactase

37

What are the symptoms of lactose intolerance

Flatulence (bacteria digest lactose in gut)
Diarrhoea (water drawn into GIT)

38

What are the three possible fates of monosaccharides

Converted to fatty acids
Glycogen storage
Energy production (glycolysis)

39

Where are insulin independent glucose transporters found

Liver
Brain
RBCs
Pancreas

40

Where are insulin dependent glucose transporters found

All other tissues

41

How is glycogen phosphorylase inhibited?

Insulin causes it to be dephosphorylated

42

How is glycogen phosphorylase stimulated?

Glycagon, Adrenaline and Ca cause it to be phosphorylated

43

What does Glycogen phosphorylase convert? What assists it?

Converts: Glycogen ---> Glycogen(n-1) + glucose-1-phosphate

It is assisted by De-branching enzyme

44

What does glucokinase do?

It converts Glucose to glucose-6-phosphate (In the liver and pancreas)

It uses one mole of ATP

45

What does hexokinase do

It converts Glucose to glucose-6-phosphate (in all tissues other than the liver and pancreas)

It uses one mole of ATP

46

Where is glucose-6-phosphatase found? What does it do?

Found in liver
Converts Glucose-6-phosphate to glucose
Releases an inorganic phosphate

47

What does branching enzyme do?

Forms alpha-1,6-glycosidic bonds from alpha-1,4-glycosidic bonds (which are made by glycogen synthase)

48

What is the rate limiting enzyme in glycogenesis

Glycogen Synthase

49

How is glycogen synthase activated?

insulin causes it to become dephosphorylated

50

How is glycogen synthase inhibited?

Glycagon and Adrenaline (in liver) cause it to become phosphorylated

51

What does glycogen synthase convert

UDP-glucose ---> Glycogen (with an extra glucose)

52

What activates Glucokinase?

Glucose
Insulin (increases amount of)

USES ONE ATP MOLECULE

53

What is type 1 glycogen-storage disease caused by?

Glycose-6-phosphatase deficiency

54

What is type 3 glycogen-storage disease caused by?

Glycogen Debranching enzyme deficiency

55

What is type 5 glycogen-storage disease caused by?

glycogen phosphorylase deficiency in muscle

56

Where does glycolysis take place?

All reactions take place in the cytosol

57

What are the inputs of aerobic glycolysis

Glucose
2x ADP
2x Pi
2x NAD+

58

What are the outputs of aerobic glycolysis

2 pyruvate
8 ATP (2 ATP + 2 NADH)

59

What are the inputs of anaerobic glycolysis

Glucose
2 ADP
2 Pi

60

What are the outputs of anaerobic glycolysis

2 lactate
2 ATP

61

How are RBCs dependent on glycolysis

Totally dependent on anaerobic glycolysis -- have no mitochondria

62

How are muscle cells dependent on glycolysis

Dependent on aerobic and anaerobic glycolysis

63

How is the brain dependent on glycolysis

Prefers aerobic glycolysis

64

How are adipocytes dependent on glycolysis

Glycolysis needed for lipogenesis and cellular energy

65

Where is glycokinase active

In the liver

66

What decreases the activity of glucokinase

Glucagon
Adrenalin

67

What inhibits the activity of hexokinase

It's product, glucose-6-phosphate

68

What does phosphofructokinase-1 do?

Converts Fructose-6-phosphate to Fructose-1,6-biphosphate

USES ONE MOLE OF ATP IN THE PROCESS

69

What increases activity of phosphofructokinase-1

high AMP concentration
high concentration of glycolytic substrates
High concentration of insulin (indirectly)

70

What decreases activity of phosphofructokinase-1

ATP
Citrate
Glucagon
Adrenalin

71

What does pyruvate kinase do

Converts Phosphoenolpyruvate (PEP) to Pyruvate

MAKES ONE ATP IN THE PROCESS

72

What increases activity of Pyruvate Kinase

fructose-1,6-biphosphate
Insulin

73

What decreases activity of Pyruvate Kinase

ATP
Glucagon

74

What does Lactate dehydrogenase do

Converts Pyruvate to Lactate

converts NADH to NAD+
Produces H- and H+ in the process

75

What increases the activity of lactate dehydrogenase

High NADH
Low NAD+

76

Overall, what stimulates glycolysis and what inhibits it

Insulin stimulates glycolysis
Glycagon inhibits glycolysis

This is unlike most other pathways

77

What does the Pentose-phosphate Pathway convert overall?

Produces rbiulose-5-phosphate from glucose-6-phosphate
Produces NADPH from NADP+

78

What is the rate limiting enzyme in the Pentose-phosphate pathway?

G6PD (Glucose-6-phosphate dehydrogenase)

79

If cells are not active, what happens to the ribulose-5-phosphate

From 3 moles of ribulose-5-phosphate:

2 moles of Fructose-6-phosphate
1 mole of Glyceraldehyde-3-phosphate

80

What is NADPH used for?

Making fatty acids, cholesterol (in liver) and steroid hormones
Reduces glutathionine (prevents oxidation-induced haemolysis)

81

What can glucose be synthesised from?

Amino acids (in particular Aspartic Acid and Alanine)
Pyruvate
Lactate
Glycerol

82

What does Fructose-1,6-biphosphotase do

Converts Fructose-1,6-biphosphate to Fructose-6-phosphate
Produces an inorganic phosphate in the process

83

What activates Fructose-1,6-biphosphatase

glucagon
ATP

84

What inhibits Fructose-1,6-biphosphatase

AMP
insulin

85

What is the rate limiting enzyme of gluconeogenesis

Phosphoenolpyruvate Carboxy Kinase

86

What activates phosphoenolpyrauvate Carboxy Kinase

Glucagon
Cortisol
Thyroid hormone

87

What inhibits Phosphoenolpyruvate Carboxy Kinase

Insulin

88

What does Phosphoenolpyruvate Carboxy Kinase do

Converts Oxaloacetate to Phosphoenolpyruvate

Converts GTP to GDP
Uses CO2

89

What does pyruvate Carboxylase Do

Converts Pyruvate into Oxaloacetate

Uses ATP (converting it to ADP + Pi) and CO2

90

What is Pyruvate Carboxylase activated by

Acetyl Co-A
Cortisol (causes increased levels)
Glucagon (cases increased levels)

91

What is necessary for the functioning of Pyruvate Dehydrogenase (PDH)

Thiamine Pyrophosphate (from Vit B1)

92

What does Pyruvate Dehydrogenase do?

Converts Pyruvate into Acetyl Co-A
Converts NAD+ into NADH
Releases CO2

93

What inhibits Pyruvate Dehydrogenase

Acetyl Co-A
NADH
ATP

94

What activates Pyruvate Dehydrogenase

Insulin
ADP
Ca

95

What casuses beriberi

Thiamine deficiency

96

What are the symptoms of beriberi

Increased plasma (lactate)
High output cardiac failure
Neurological symptoms

97

What two groups of people is beriberi common in?

Alcoholics (Alcohol inhibits vitamin B1 absorption)
Populations that rely on polished rice

98

What does Alcohol Dehydrogenase do

Converts ethanol to acetaldehyde
Converts NAD+ to NADH in the process

99

What does Aldehyde Dehydrogenase do

Converts acetaldehyde to Acetic Acid
Converts NAD+ to NADH in the process

100

What inhibits aldehyde dehydrogenase

Anabutase

101

Where is aldehyde dehydrogenase active

In the mitochondria

102

What can lead to acetaldehyde accumulation

Increased Alcohol Dehydrogenase Activity
Decreased Aldehyde Dehydrogenase Activity

103

Why is acetaldehyde toxic

hangover symptoms
Vasodilation
Cellular damage

104

What is the result of increased NADH from alcohol metabolism

Leads to conversion of pyruvate to lactate, inhibiting gluconeogensis and leading to hypoglycaemia

Decreased NAD+ in mitochondria -
- slows TCA/krebs cycle
- slows catabolism of fatty acids (leads to a fatty liver)

105

What is the result of increased Acetyl Co-A from ethanol metabolism

Results in ketone body synthesis and production of fatty acids

106

What happens in the Cori Cycle

Lactate is transported to liver to produce glucose

107

What happens in the Alanine/Glucose-alanine cycle

Alanine is transported to the liver to produce glucose

108

What does:
1: Low glucose uptake into cells
2: increased glucose release from cells
result from

Low Insulin
High Glucagon, Adrenalin and Cortisol

109

What does:
1: High Glycogen synthesis
2: Low Gluconeogenesis
result from

High insulin
Low Glucagon, Adrenalin and Cortisol

110

What does:
1: Low glycolysis
2: High glycogenolysis
result from

Low Insulin
High Glucagon, Adrenalin and Cortisol

111

How is diabetes mellitus diagnosed?

1: Fasting blood glucose is above normal
2: Abnormal glucose tolerance test

112

How is a glucose tolerance test performed?

1: Fast for 8 hours
2: Subject given 75g of glycose measured every 30 min for 3 hours

IN NORMAL PERSON, BLOOD GLUCOSE DROPS BACK DOWN AFTER 2 HOURS

113

What is the metabolic profile of a type 1 diabetic

No insulin. Slightly increased glucagon (lack of insulin inhibition)

Increased blood glucose concentration:
1 - No insulin: Decreased uptake of glucose into cells
2 - Uninhibited glucagon: Increased glycogenolysis and gluconeogenesis

114

What is the metabolic profile of a type 2 diabetic

Decreased ability for insulin to cause cellular response:
1: Decreased uptake of glucose into cells
2: Decreased inhibition of -- glycogenolysis, gluconeogenesis

115

What does Glucose-6-phosphate dehydrogenase do?

converts glucose-6-phosphate to 6-phosphgluconate
Uses H2O
Converts NADP+ to NADPH

116

What is Fructose-1,6-biphosphate converted to

Converted to either Dihydroxyacetone Phorphate OR Glyceraldehyde-3-phosphate

117

What is glyceraldehyde-3-phosphate converted to?

Conterted to 1,3-biphosphoglycerate
Converts ADP to ATP along the way

OR

Converted to 2,3-biphosphoglycerate

118

What is 2,3-biphosphoglycerate converted to

Converted to 3-phosphoglycerate
Releases an inorganic phosphate

119

What is the function of 2,3-biphosphoglycerate

Decreases haemoglobin affinity for O2

120

What is the function of AST

Converts Aspartate to Oxaloacetate

121

What is the function of ALT (Alanine Transaminase)?

Converts Alanine to pyruvate

122

What is acetic acid converted to?

Acetyl Co-A

Uses Co-enzyme A
Uses ATP