Carbohydrates Flashcards Preview

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Flashcards in Carbohydrates Deck (133):
1

This type of pathway is the link between anabolic and catabolic pathways

Amphibolic

2

Krebs cycle is an example of what type of pathway?

Amphibolic

3

Protein kinase of cAMP

Protein kinase A

4

Protein kinase of IP3/DAG

Protein kinase C

5

Sugar units are linked together by what type of bond

Glycosidic bond

6

Mirror image of a carbohydrate

Enantiomer

7

Hexose monosaccharides

Glucose
Fructose
Galactose
Mannose

8

Pentose monosaccharides

Ribose
Ribulose
Xylulose

9

Oxidation of glucose yields

Glucuronic acid

10

Reduction of glucose yields

Sorbitol

11

Monosaccharide that is a constituent of glycoproteins

Mannose

12

Monosaccharide that is a structural component of nucleic acids and coenzymes

Ribose

13

Monosaccharide that is an intermediate in the pentose phosphate pathway

Ribulose

14

Monosaccharide that is excreted in urine in essential pentosuria

Xylulose

15

Glucose plus fructose

Sucrose

16

Glucose plus galactose

Lactose

17

Glucose plus glucose

Maltose

18

Most important dietary carbohydrate in cereals, potatoes, legumes with alpha glycosidic bonds

Starch

19

Found in plant cell walls

Cellulose

20

Polysaccharide of fructose that is readily soluble in water

Inulin

21

Insulin stimulated glucose transporter

GLUT 4

22

Glucose transporter in brain

GLUT 1 and 3

23

Glucose transporter in liver and pancreas

GLUT 2

24

Glucose transporter in placenta

GLUT 1 and 3

25

Glucose transporter in RBC

GLUT 1

26

Glucose transporter in small intestine

BM- glut 2
Lumen- glut 5

27

Where does glycolysis occur?

Cytosol

28

Rate limiting step of glycolysis

Fructose 6 phosphate to fructose 1,6 bisphosphate

PFK 1

29

NET ATP in glycolysis

2 ATPs

4 generated
2 consumed- step 1 and 3

30

Enzyme in the 1st step of glycolysis that has low Km and high affinity

Hexokinase

31

Enzyme in the phosphorylation of glucose that is only present in the liver and pancreas

Glucokinase

32

Enzyme inhibited by fructose 6 phosphate

Glucokinase

33

Inhibited by glucose 6 phosphate

Hexokinase

34

Activator of PFK 1

Fructose 2,6 bisphosphate that is a product of PFK 2

35

PFK 2 is activated during the

Well fed state

36

Inhibits PFK 1

Citrate

37

2 steps in glycolysis that produce ATP

1,3 BPG to 3 phosphoglycerate by phosphoglycerate kinase

Phosphoenolpyruvate to pyruvate by pyruvate kinase

38

Step in glycolysis that produces NADH

Glyceraldehyde 3 phosphate to 1,3 BPG by glyceraldehyde 3P dehydrogenase

39

In anaerobic glycolysis, pyruvate is converted to lactate by

Lactate dehydrogenase

40

Which tissues use glycerophosphate shuttle?

Brain

41

Energy yield of glycerophosphate shuttle

1 FADH= 1.5 ATP

42

Which tissues use malate aspartate shuttle

Heart, most tissues

43

Energy yield of malate aspartate shuttle

1 NADH= 2.5 ATP

44

Net ATP yield in aerobic glycolysis

5 or 7

45

Net ATP yield in anaerobic glycolysis

2

46

Found in RBC where step catalyzed by phosphoglycerate kinase is bypassed

2,3 BPG

47

1,3 BPG is converted to 2,3 BPG by this enzyme

Bisphosphoglycerate mutase

48

4 fates of puruvate

Lactate- lactate dehydrogenase
Acetyl CoA- pyruvate dehydrogenase
Ethanol- pyruvate decarboxylase
Oxaloacetate- pyruvate carboxylase

49

Pyruvate is converted to Acetyl CoA through this enzyme

Pyruvate dehydrogenase

50

Coenzymes of pyruvate dehydrogenase

Thiamine
FAD
NAD
Coenzyme A
Lipoic acid

51

Most common enzyme defect in glycolysis

Pyruvate kinase

52

Pyruvate kinase deficiency can lead to

Hemolytic anemia

53

Deficiency in muscle PFK can lead to

Low exercise capacity

54

Most common cause of congenital lactic acidosis

Pyruvate dehydrogenase deficiency

55

Maturity onset diabetes of the young type 2 is due to mutations that decrease the activity of this enzyme in glycolysis

Glucokinase

56

What element competes with inorganic phosphate as substrate for glyceraldehyde 3P dehydrogenase

Arsenic

57

Chronic alcoholism leads to this vitamin deficiency

Thiamine

58

Final common pathway for the aerobic oxidation of carbohydrates, lipid and proteins

Citric acid cycle

59

Major pathway for formation of ATP

Citric acid cycle

60

Citric acid cycle occurs in what part of the cell

Mitochondria

61

Substrate for glycolysis

Glucose

62

Substrate for citric acid cycle

Acetyl CoA

63

Products of Krebs

2 CO2
1 GTP
3 NADH
1 FADH

64

Rate limiting step of Krebs

Isocitrate to alpha ketoglutarate by isocitrate dehydrogenase

65

Which step in Krebs produces GTP?

Succinyl CoA to succinate step by substrate level phosphorylation

66

Which step in Krebs produces FADH?

Succinate to fumarate step

67

Which step in Krebs produces CO2 and NADH?

Isocitrate to a ketoglutarate
Alpha ketoglutarate to succinyl CoA
Malate to oxaloacetate

68

TCA intermediate that delivers acetyl CoA to the cytosol for FA synthesis

Citrate

69

TCA intermediate used in heme synthesis and ketone body activation

Succinyl CoA

70

TCA intermediate that may be used in gluconeogenesis

Malate

71

True or false:

TCA has hormonal control

False

72

ATP yield for TCA

10 ATP
3 NADH, 1 FADH, 1 GTP

73

Complete oxidation of glucose yields how many ATP

30 or 32

74

Pathways occurring in both cytosol and mitochondria

HUG
heme synthesis
Urea cycle
Gluconeogenesis

75

Gluconeogenesis occurs in what organs?

Liver and kidney

76

Gluconeogenesis substrates

Intermediates from glycolysis or TCA
Glycerol and propionyl CoA from TAG
Lactate through Cori cycle
Glucogenic amino acids

77

Rate limiting step of gluconeogenesis

Fructose 1,6 bisphosphate to fructose 6 phosphate through fructose 1,6 bisphosphatase

78

The reaction catalyzed by pyruvate carboxylase in gluconeogenesis requires

Biotin and ATP

79

All carboxylases require this as a cofactor

Biotin

80

Oxaloacetate to phosphoenolpyruvate by PEP carboxykinase requires

GTP

81

Final step in gluconeogenesis that is shared with glycogenolysis

G6P to glucose by glucose 6 phosphatase

82

Pathway where lactate formed by glycolysis in skeletal muscle is transported to liver where it is converted back to glucose through gluconeogenesis

Cori cycle

83

Gluconeogenesis energy requirement

Cleavage of 6 high energy phosphate bonds- 2 GTP and 4 ATP
2 NADH

84

Hyperglycemia in critically ill patients can be attributed to

Excessive gluconeogenesis in response to injury and infection

85

Major storage carbohydrate in animals

Glycogen

86

Glycogenolysis occurs in what organs?

Liver and muscle

87

Where does glycogenesis occur?

Cytosol

88

Rate limiting step of glycogenesis

Elongation of glycogen chains through glycogen synthase

89

Protein that serves as a primer for glycogen synthesis when glycogen is completely depleted

Glycogenin

90

Glucose is attached to _________ and becomes the source of all glucosyl residues that are added to the glycogen molecule

Uridine diphosphate

91

Enzymes in synthesis of UDP glucose

Phosphoglucomutase
UDP glucose pyrophosphorylase

92

A(1-6) bonds are formed by transferring how many glucosyl residues?

5-8

93

Products of glycogenolysis

Glucose in liver
Glucose 6 phosphate in muscle

94

Rate limiting step of glycogenolysis

Shortening of glycogen chains by glycogen phosphorylase

95

Coenzyme of glycogen phosphorylase

Pyridoxal phosphate

96

Limit dextrin is when there are only how many glucosyl units remaining?

4

97

Debranching enzyme consists of

Alpha 1-4 glucantransferase
Alpha 1-6 glucosidase

98

Lysosomal degradation of glycogen is through this enzyme

Acid maltase
(Alpha 1-4 glucosidase)

99

Von Gierke happens in this enzyme deficiency

Glucose 6 phosphatase

100

Deficiency in lysosomal acid maltase results to

Pompe disease

101

Glycogen storage disease where there is fasting hypoglycemia and muscle weakness due to deficient debranching enzyme

Cori disease

102

Disease where there is increased limit dextrin

Cori cycle

103

Deficient branching enzyme where there is hepatosplenomegaly, increased polysaccharides and heart and liver failure by age 5

Andersen disease

104

McArdle disease where there is poor exercise tolerance is due to deficient

Muscle phosphorylase

105

Hers disease is caused by deficiency in

Liver phosphorylase

106

Galactose to galactose 1P is due to which enzyme

Galactokinase

107

UDP galactose to UDP glucose is mediated by which enzyme

UPD hexose 4 epimerase

108

This enzyme deficiency can cause cataracts in early childhood

Galactokinase

109

This enzyme deficiency can cause vomiting, jaundice, poor growth in children, MR and premature ovarian failure

Galactose 1 phosphate uridyl transferase (GALT) deficiency

110

Fructose 1 P to DHAP

Aldolase B

111

Fructose 1,6 BP to DHAP

Aldolase A

112

Aldolase B defiency can cause these symptoms

Hypoglycemia and vomiting after fructose or sucrose consumption

113

Glucose to sorbitol is catalyzed by

Aldose reductase

114

Sorbitol to fructose is mediated by sorbitol dehydrogenase and is found in these organs

Liver
Ovaries
Seminal vesicles

115

Deficiency in which disaccharide occurs in Inuit people of Greenland and Canada

Sucrase Isolmaltase complex deficiency

116

Alternative pathway for oxidation of glucose in the liver

Uronic acid pathway

117

Main pathway for glucuronic and iduronic acid

Uronic acid pathway

118

Humans cannot synthesize ascorbic acid because of the lack of

L-gulonolactone oxidase

119

Essential component of glycosaminoglycans and detoxification of bilirubin, steroids and morphine

Glucuronic acid

120

Products of pentose phosphate pathway

NADPH
Ribose 5 phosphate

121

Pathway that neither consumes nor produces ATP

HMP shunt

122

Rate limiting step of pentose phosphate pathway

Glucose 6P to 6 phosphogluconate

Glucose 6P dehydrogenase

123

G6P dehydrogenase is the key enzyme in which phase of the HMP shunt?

1st phase

124

What phase of the PPP is oxidative and irreversible?

1st phase

125

What is the product of the 1st phase of PPP

2 NADPH

126

What is the enzyme of the 2nd phase of the HMP shunt?

Transketolases

127

Cofactor of transketolases in the pentose phosphate pathway

Thiamine

128

Product of the 2nd phase of PPP

Ribose 5 phosphate

129

This substance removes H2O2 in a reaction catalyzed by glutathione peroxidase

Glutathione

130

Most common disease producing enzyme abnormality

G6PD deficiency

131

Pathology in G6PD where there is altered hemoglobin that precipitates in the RBC

Heinz bodies

132

Abnormally shaped RBCs in G6PD due to phagocytic removal of Heinz bodies in spleen

Bite cells

133

Disease that is due to NAPH oxidase deficiency that converts molecular oxygen into superoxidase and used in respiratory burst that kills bacteria

Chronic Granulomatous Disease