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Biochemistry > Pentose (aka Hexose Monophosphate Shunt) > Flashcards

Pentose (aka Hexose Monophosphate Shunt) Flashcards

1
Q

PPP consists of two phases: _____ reactions (irreversible) and _____ reactions (reversible).

A

Oxidative reactions (irreversible), Nonoxidative reactions (reversible)

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2
Q

_____ reactions go to glycolysis as a result.

A

Nonoxidative

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3
Q

NADPH is generated when ______ is oxidized to ribulose-5-phosphate. This is ______ reaction phase.

A

Glucose-6-phosphate, Oxidative reaction phase

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4
Q

The ______ is used in the reductive biosynthesis and detoxification.

A

NADPH

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5
Q

What are the biosynthesis pathways? (4)

A

Fatty acid, cholesterol, nucleotide, and neurotransmitter biosynthesis.

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6
Q

What are the two detoxification systems?

A

Reduction of oxidized glutathione, and cytochrome P450 monooxygenases.

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7
Q

Through which phase does the pathway catalyzes the interconversion of 3,4,5,6 and 7 Carbon sugars?

A

Nonoxidative phase

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8
Q

What are the substrates for 3,4,5,6 and 7 carbon sugars?

A

3- G-3-P, 4- Erythrose-4-phosphate, 5- Ribose-5-phosphate and xylulose-5-phosphate, 6- Fructose-6-Phosphate, 7- Sedoheptulose-7-phosphate

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9
Q

Which five-carbon sugar is the most important?

A

Ribose-5-phosphate

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10
Q

_____ is a component of RNA and DNA, as well as ATP, NADH, FAD, and coenzyme A

A

Ribose-5-phosphate

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11
Q

How many molecules of NADPH are generated in the conversion of glucose-6-phosphate into ribulose-5-phosphate?

A

2 NADPH

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12
Q

What is the rate-limiting enzyme in the irreversible (Oxidative reaction) pathway?

A

Glucose-6-phosphate dehydrogenase.

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13
Q

What is the stoichiometry for oxidative phase?

A

Glucose-6-phosphate+ 2NADP => Ribulose-5-phosphate+ 2NADPH

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14
Q

What is the product yield by enzyme ribulose-5-phosphate isomerase?

A

Ribose-5-phosphate (R5P)

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15
Q

What is the product yield by the enzyme ribulose-5-phosphate epimerase?

A

Xylulose-5-phosphate (Xu5P)

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16
Q

The pentose phosphate pathway and glycolysis are linked by ______ and ______

A

Transketolase and Transaldolase

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17
Q

Thiamine pyrophosphate (TPP) is a coenzyme for ______.

A

Transketolase

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18
Q

TPP is also a coenzyme to the ______ of the Pyruvate dehydrogenase complex.

A

E1 subunit

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19
Q

What are the products that are yield by the enzyme transketolase? What is the coenzyme for this enzyme?

A 
Fructose-6-phosphate (F6P) and Glyceraldehyde-3-phosphate (GAP);
Thiamin Pyrophosphate (PTT)
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20
Q

What is the first RL enzyme?

A

Glucose-6-phosphate dehydrogenase

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21
Q

What is the second RL enzyme?

A

Phospho-gluconate dehydrogenase

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22
Q

The two RL enzymes both yield, and are the only two enzymes that yields NADPH. T/F?

A

True

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23
Q

Which substrate makes DNA and RNA?

A

Ribose-5-phosphate

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24
Q

Which substrates are sent to glycolysis?

A

G-3-P and F-6-P

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25
Q

Glucose-6-phosphate is oxidized to____

A

6-Phosphoglucono-lactone

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26
Q

The RL enzyme Glucose-6-phosphate dehydrogenase (G6PD) is controlled by the substrate availability of _____

A

NADP+

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27
Q

When the cell consumes NADPH, the _____ concentration rises, increasing the rate of Glucose-6-phosphate dehydrogenase activity, thereby stimulating ____ regeneration.

A

NADP+

NADPH

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28
Q

____ enhances G6PD gene expression and therefore flux through the pathway increases in the well-fed state.

A

Insulin

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29
Q

NADPH is a high-energy molecule whose electrons are used in ________, rather than for the transfer to oxygen as is the case with NADH.

A

Reductive biosynthesis

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30
Q

What tissues are rich in pentose phosphate pathway enzymes?

A

Tissues that are heavily involved in fatty acid and cholesterol biosyntheses.

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31
Q

In the live __% of the glucose oxidation occurs via the pentose phosphate pathway.

A

30%

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32
Q

Tissues with active pentose phosphate pathways:

A

Liver, adipose tissue, mammary gland, adrenal gland, testes, ovaries, red blood cell

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33
Q

Function in Liver

A

Fatty acid and cholesterol synthesi

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34
Q

Functions in Adipose tissue

A

Fatty acid synthesis

35
Q

Functions in Mammary gland

A

Fatty acid synthesis

36
Q

Functions in Adrenal gland

A

Steroid synthesis

37
Q

Functions in Testes

A

Steroid synthesis

38
Q

Functions in Ovaries

A

Steroid synthesis

39
Q

Functions in RBC

A

Maintenance of reduced glutathione

40
Q

The generation of reactive oxygen species (ROS) Sequence:

A

Oxygen->Superoxide->Hydrogen peroxide->Hydroxyl radical (each ‘->’ has an electron being added)

41
Q

Reactive oxygen species are formed continuously as by-products of aerobic metabolism, and they can cause serious chemical damage to ___, ___ and ___ in the cell’s membrane.

A

DNA, proteins, and unsaturated fatty acids

42
Q

What is the body’s most powerful endogenous anioxidant?

A

GLUTATHIONE

43
Q

What is the cofactor for glutathione peroxidase?

44
Q

Glutathione cycle uses what two enzyme?

A

Glutathione reductase, and glutathione peroxidase.

45
Q

If G6PD is compromised, NADPH levels will___, and glutathione cannot be reduced resulting in H2O2 accumulation which will lead to the _____ of the cell’s membrane.

A

Fall

Destabilization

46
Q

Cytochrome P450 (Monooxygenase system) incorporate one atom from molecular oxygen into an aliphatic substrate thereby creating a _____ group and generating a _____ product.

A

Hydroxyl group

Water soluble product

47
Q

What is the function of Cytochrome P450 Mitochondrial system?

A

Function is to participate in the hydroxylation of steroids, a process that makes these hydrophobic compounds more water soluble. (Estrone to Estradiol)

48
Q

What is the function of Cytochrome P450 Microsomal system?

A

Function is the detoxification of foreign compounds (xenobiotics).

49
Q

Microsomal system is also found associated with the membranes of the _____.

A

Smooth ER (particularly in the liver)

50
Q

Mitochondrial system is used by which organ to hydroxylate 25-hydroxycholecalciferol (Vit. D) to its biologically active form 1,25-dihydroxycholecalciferol?

51
Q

Microsomal system participates in the hydroxylation of xenobiotics to make them more water soluble, thus facilitating their excretion via the____ or ___.

A

Kidney or bile

52
Q

What does Cytochrome P450 reductase use?

53
Q

________ is a xenobiotic commonly produced from the burning of coal, from the combustion of tobacco, or from food barbecued on charcoal briquettes.

A

Benzo[a]pyrene

54
Q

Benzo[a]pyrene, a weak ____, is metabolized by _____ (such as 1A1, 1A2, and 1B1) to a potent carinogen.

A

Carcinogen

Cytochrome P450’s

55
Q

Benzo[a]pyrene loves to bind to___ and ___

A

Adenine, and guanine

56
Q

Benzo[a]pyrene will put ___ groups on P450?

A

Hydroxyl groups

57
Q

Sequence of leading to cancer

A 
Activation of oncogenes.
Inactivation of DNA repair genes.
Inactivation of tumor suppressor genes.
Inactivation of apoptosis genes. 
Cancer.
58
Q

Cytochrome P450 2E1 also mediates the metabolism of ______

A

Acetaminophen (found in Tylenol)

59
Q

If alcohol and acetaminophen are taken at the same time, does alcohol compete with acetaminophen for metabolism by Cyto P450 2E1?

60
Q

When drinking, Cyto P450_____. What happens to NAPQI and GSH?

A

Acute NAPQI build up, and GSH will run out.

61
Q

Acetaminophen causes____.

A

Lipofection

62
Q

What is phase 1 detox?

63
Q

What is phase 2 detox?

64
Q

If both detox are not working what would happen?

A

Cell death.

65
Q

Phagocytosis and the Respiratory Burst using NADPH oxidase is performed by ____, _____, and _____.

A

Macrophages, neutrophils and monocytes

66
Q

What is the Fenton Reaction?

A

Attachment of the pathogen to a phagocytic cell.
Ingestion of the microorganism.
Destruction of the microorganism via NADPH (Reducing agent) causes respiratory burst.

67
Q

What are the substrates for Nitirc oxide synthase(NOS)?

A

Arginine, O2, and NADPH

68
Q

What are the co-enzymes for NOS?

A

FMN, FAD, and tetrahydrobiopterin

69
Q

Arginine+NADPH=?

A

Nitric oxide

70
Q

Nitric oxide is a ______ with an average life span of 3to 10 secondds.

A

Free radical

71
Q

What is Endothelial nitric nitric oxide synthase?

A

An endogenous vasodilator, where as nitroglycerine and Viagra will produce exogenous NO.
AKA Endothelium derived relaxing factor.

72
Q

Neuronal nitric oxide synthase (nNOS) function?

A

Functions as a neurotransmiter in brain.

73
Q

What is Inducible nitric oxide synthase (iNOS)?

A

Medeiates turmoricidal and bactericidal actions of macrophages.

74
Q

What is Glucose-6-phosphate dehydogenase deficiency?

A

An X-linked inherited disease characterized by hemolytic anemia.

75
Q

G6PD deficiency impairs the ability of an erythrocyte to form ____, resulting in hemolysis.

76
Q

G6PD deficiency is common, affecting more than 400 million people in the Mediterranean, Middle East, Southeast Asia, and tropical parts of Africa. Why is this?

77
Q

G6PD deficiency is a genetic mutation that will serve as a protection of?

78
Q

Does everyone has the same Km for G6PD?

79
Q

People with G6PD deficiency has the risk of developing what?

A

Hemolytic anemia

80
Q

Hemolytic anemia can be caused if exposed to? (3)

A

Significant infections

Patients treated with peroxide generating drugs such as sulfa antibiotics, the antimalarial drug Primaquine or the ANTIPYRETIC ACETANILIDE.

Ingestion of fava beans.

81
Q

Significant infections: The inflammatory resonse to infection results in the generation of peroxides in macrophages, which can diffuse from the macrophages into the erythrocytes and cause______.

A

Oxidative damage

82
Q

What is Favism?

A

Ingestion of fava beans, a dietary staple of the Mediterranean, can cause hemolytic anemia.

83
Q

What molecule is found in Fava bean that acts as an antimalarial drug?

Biochemistry (10 decks)

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