✅ BIOCHEM - Metabolic Pathways Flashcards Preview

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Flashcards in ✅ BIOCHEM - Metabolic Pathways Deck (118):
1

Example of an amphibolic pathway

Krebs

2

Where does glycolysis occur?

Cytoplasm

3

Substrate of glycolysis

Glucose

4

End product of glycolysis

Pyruvate or lactate

5

Rate limiting step of glycolysis

Fructose 6 phosphate -> fructose 1,6 bisphosphate
Enzyme: PFK-1

6

What type of glycolysis happens in cells with mitochondria and adequate O2?

Aerobic glycolysis

7

2 stages of glycolysis

Energy investment and energy generation

8

3 important steps in glycolysis

Step 1
Step 3
Step 10

9

NADH generating step in glycolysis

Glyceraldehyde 3 phosphate --> 1,3 bisphosphoglycerate
Enzyme: glyceraldehyde phosphate dehydrogenase

10

Which has a lower km and comsequently higher affinity?
Hexokinase or glucokinase?

Hexokinase

11

Glucokinase is present only in what type of tissues

Liver
Islet cells of pancreas

12

Hexokinase has a higher Vmax than glucokinase. True or false.

False
Glucokinase has a higher Vmax

13

Hexokinase is inhibited by

Glucose 6 phosphate

14

Glucokinase is inhibited by

Fructose 6 phosphate

15

Glucokinase liver activity is induced by

Insulin

16

Action of PFK-2

Converts fructose 6 phosphate to fructose 2,6 BP

17

Inhibitor of PFK-1

ATP and Citrate

18

Inhibitor of PFK 2

Starved state
Decrease insulin and inc glucagon

19

2 steps in glycolysis that produce ATP via substrate level phosphorylation

1,3 BPG to 3 PG
Enzyme: phosphoglycerate kinase

PEP to pyruvate
Enzyme: pyruvate kinase

20

2 outcomes of pyruvate in glycolysis

Can enter the citric acid cycle in aerobic glycolysis
Can be reduced to lactate in anerobic glycolysis

21

NADH produced in glycolysis cannot pass through thr mitochondrial membrane so it needs what?

Malate aspartate shuttle
Glycerol phosphate shuttle

22

Malate aspartate shuttle is used in what organs?

Liver kidney heart

23

Glycerol phosphate shuttle is used in which organs?

Skeletal muscle
Brain

24

Kinds of metabolic pathways

Anabolic
Catabolic
Amphibolic

25

NADH in the malate aspartate shuttle will yield how many ATP?

3

26

NADH in the glycerol phosphate shuttle will yield how many atp?

2

27

In what part of the cell can u find the ETC?

Inner mitochondrial membrane

28

What happens to pyruvate in anaerobic glycolysis?

Lactate dehydrogenase uses up NADH and converts pyruvate to lactate.

29

Anaerobic glycolysis strictly happens in which organs?

Cornea
Lens
Kidney medulla
Wbc
Rbc
Testes

30

Enzyme responsible for conversion of 1,3 BPG to 2,3 BPG

Bisphosphoglycerate mutase

31

The Luebering-Rapoport pathway bypasses what enzyme

Phosphoglycerate kinase

32

Most common enzyme defect in glycolysis

Pyruvate kinase deficiency

33

Characteristic peripheral smear of G6PD deficiency

Heinz bodies

34

Most common precipitating history of G6PD

Infection

35

Pyruvate is converted to ethanol by

Pyruvate carboxylase (yeasts)

36

Pyruvate is converted to oxaloacetate by

Pyruvate carboxylase (gluconeogenesis)

37

What is the mechanism in arsenic poisoning?

Arsenic inhibits pyruvate dehydrogenase by binding to LIPOIC ACID

38

Pyruvate is converted to acetyl Coa by

Pyruvate dehydrogenase complex

39

Coenzymes of pyruvate dehydrogenase

Thiamine pyrophosphate
FAD
NAD+
Coenzyme A (Pantothenic Acid)
Lipoic Acid

40

Pyruvate kinase deficiency usually manifests clinically as

Chronic hemolytic anemia

41

Products of conversion of pyruvate to acetyl coa

Acetyl coa
NADH
CO2

42

Most common cause of congenital lactic acidosis

Pyruvate dehydrogenase deficiency

43

Pattern of inheritance of pyruvate kinase deficiency

X-linked DOMINANT

44

Treatment for pyruvate dehydrogenase deficiency

Ketogenic diet

45

Rationale for ketogenic diet in pyruvate dehydrogenase deficiency

Increase lysine and leucine to bypass glycolysis

46

Mechanism of pyruvate dehydrogenase deficiency in chronic alcoholism.

Thiamine deficiency (acquired)

47

Where does the Kreb's cycle occur?

Mitochondrial matrix

48

TCA occurs in the mitochondrial matrix except for which process?

Succinate to fumarate
Enzyme: succinate dehydrogenase

49

Rate limiting step in krebs

Isocitrate to alpha ketoglutarate
Enzyme: isocitrate dehydrogenase

50

Inhibitor of aconitase

Fluoroacetate (rat poison)

51

Inhibitor of alpha ketoglutarate dehydrogenase

Arsenite

52

Process in the TCA that produces GTP

Succinyl Coa to succinate
Enzyme: succinate thiokinase

53

Citrate delivers acetyl Coa to the cytoplasm for ______ via the _______

Fatty acid synthesis via the citrate shuttle

54

Succinyl coa in TCA is also involved in _______

Heme synthesis
Activation of ketone bodies in extrahepatic tissues

55

Malate in TCA is also use for

Gluconeogenesis

56

What is the main function of gluconeogenesis

Prevent hypoglycemia

57

What is the main function of the Cori cycle?

Conversion of lactate to glucose

58

Gluconeogenesis occurs in which organs

Liver 60% and kidney 10%

Prolonged fasting: kidney up to 40%

59

Gluconeogenesis occur in the

Cytoplasm and mitochondria

60

Rate limiting step in gluconeogenesis

Fructose 1,6 bisphosphate to fructose 6 phosphate
Enzyme: fructose 1,6 bisphosphatase

61

Energy expense in the cori cycle

4 ATPs

62

In glucogeonesis pyruvate is converted back to PEP through which of the following steps?

Pyruvate to OAA
Enzyme: Pyruvate carboxylase

OAA to PEP
Enzyme: PEP Carboxykinase

63

All carboxylases require _____ as a cofactor

Biotin

64

PEP carboxykinase require ____

GTP

65

Inhibitor of fructose 1,6 BP to fructose 6-P in gluconeogenesis

Fructose 2,6 BP and AMP

66

Energy expenditure in gluconeogenesis

4Atps
2 gtps
2 NADH to NAD+

67

Glucosuria occurs when venous blood glucose concentration exceeds

9.5-10 mmol/L (renal threshold)
180 g/dl

68

Redness when drinking is due to which enzyme

Acetaldehyde dehydrogenase

69

High amounts of NADH favors the ff reactions

Pyruvate to lactate
OAA to malate
DHAP to glycerol 3 phosphate

70

Insulin resistance in pregnancy is due to

Human placental lactogen

71

Hyperinsulinemia in pregnancy is due to

Increased estrogen levels

72

Major carbohydrate storage in animals

Glycogen

73

Processes that happen in the cytoplasm and mitochondria

Gluconeogenesis
Urea synthesis
Heme synthesis

74

Glycogen stores are used up after

12-18 hours

75

Glycogen is stored in which 2 organs?

Liver and muscle

76

Activated form of glucose

UDP-glucose

77

Synthesis of new glycogen molecules from alpha-d-glucose

Glycogenesis

78

Rate limiting step in glycogenesis

Elongation of glycogen chains
Enzyme: glycogen synthase

79

Enzyme involved in conversion of glucose 6 phosphate to glucose 1 phosphate

Phosphoglucomutase

80

Enzyme involved in the synthesis of UDP glucose

UDP glucose phosphorylase

81

Formation of branches in glycogen is mediated by what enzyme

Branching enzyme (amylo and transglucosidase)

82

Glycogen synthase is to glycogenesis
_____ is to glycogenolysis

Glycogen phosphorylase

83

Glycogen phosphorylase requires what coenzyme

Pyridoxal phosphate

84

Glycogen phosphorylase cannot cleave a 4 glucose residue before a branch called the

Limit dextrin

85

Rate limiting step in glycogenolysis

Removal of glucose using glycogen phosphorylase

86

Lysosomal degradation of glycogen happens with what enzyme

Alpha 1,4 glucosidase

87

Other name of alpha 1,4 glucosidase

Acid maltase

88

In glycogen phosphorylase, the active form is the phosphorylated or dephosphorylated?

Phosphorylated

89

Deficiency in acid maltase

Pompe disease

90

Deficiency in glucose 6 phosphatase

Von gierke disease

91

Deficiency in skeletal muscle glycogen phosphorylase

McArdle's disease

92

Deficient in Andersen's disease

Branching enzyme

93

Cori's disease deficiency

Debranching enzyme

94

Deficient PFK

Tarui's disease

95

Major dietary source of galactose

Lactose

96

Activated form of galactose

UDP galactose

97

Glucose 1 phosphate + UDP glucose forms _____ through which enzyme

UDP galactose and glucose 1 phosphate

Enzyme: galactose 1 P uridyl transferase

98

UDP galactose --> UDP galactose
Enzyme?

UPD hexose 4 epimerase

99

Main products of the pentose phosphate pathway

NADPH
Ribose 5 phosphate

100

Substrate of the pentose phosphate pathway

Gucose 6 phosphate

101

The pentose phosphate pathway is divided into the

Oxidative and non oxidative phase

102

Main product of the oxidative phase of the PPP

NADPH
Ribulose 5 P

103

Phase 1 of PPP is

Oxidative and irreversible

104

Key enzyme in oxidative phase of pentose phosphate pathway

G6PD

105

Key enzymes in non-oxidative phase of the pentose phosphate pathway

Transketolases

106

Transketolases require

Thiamine

107

Rate limiting step in the pentose phosphate pathway

Glucose 6 P to 6 phosphogluconate
Enzyme: G6PD

108

Reduced glutathione is recreated using

NADPH
Enzyme: glutathione REDUCTASE

109

Reduced glutathione sequestere harmful H2O2 using

Glutathione peroxidase

110

Drugs that precipitate G6PD deficiency

AAA

Antibiotics (sulfonamides, chloramphenicol)
Antimalarials (primaquine)
Antipyretics (except ASA and Paracetamol)

111

Chronic granulomatous disease is secondary to to deficiency in

NADPH OXIDASE

112

Chronic granulomatous disease is caused by what type of bacteria

Catalase positive

113

Sorbitol dehydrogenase is found in

The seminal vesicles only

Catalyzes sorbitol to fructose (main sperm energy source)

114

Glucose to sorbitol
What enzyme?

Aldose reductase

115

Mannise is an important component in

Glycoproteins

116

How is mannose 6 P used?

Mannose 6 P is converted to fructose 6 P by
Phosphomannose isomerase

117

Fructose 1 P to dihydroxyacetone phosphate
What enzyme?

Aldolase B

118

Fructose to fructose 1 P

Fructokinase or hexokinase