Pentose Phosphate Pathway and NADPH Flashcards Preview

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Flashcards in Pentose Phosphate Pathway and NADPH Deck (42)
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1
Q

Other name for the Pentose Phosphate Pathway

A

Hexose MonoPhosphate (HMP) shunt

2
Q

This pathway is a branch off of the

A

glycolytic pathway

3
Q

The two main purposes of this pathway are:

A
  1. Generation of NADPH

2. Generation of the 5-C sugar ribose (to be used in synthesis of nucleotides)

4
Q

Depending on the needs of the cell, the pathway can produce:

A

Either:
-both ribose and NADPH
or
-either NADPH or ribose

5
Q

The net total ATP used and produced in this pathway is

A

zero; none are produced or used

6
Q

Name the Oxidative Irreversible Reactions of HMP

A

Step 1: Dehydrogenation of Glucose 6-P
Step 2: Hydrolysis to 6-phosphogluconate
Step 3: Oxidative decarboxylation of 6-phosphogluconate

7
Q

Name the enzyme responsible for Step 1 of the Oxidative Irreversible Reaction:

A

Glucose 6-phosphate dehydrogenase (G6PD)

8
Q

Which step within the Oxidative Irreversible Reactions of HMP is the rate-limiting step?

A

Step 1: Dehydrogenation of Glucose 6-P

9
Q

Which enzyme within the Oxidative Irreversible Reactions requires NADP+ as a coenzyme?

A

Glucose 6-phosphate dehydrogenase (G6PD)

10
Q

What molecule is a potent competitive inhibitor within Step 1 of the Oxidative Irreversible Reactions?

A

NADPH

11
Q

Expression of G6PD is upregulated by

A

insulin

12
Q

The flux of G6PD through the pathway is increased in the

A

absorptive state

13
Q

Name the enzyme responsible for Step 2 of the Oxidative Irreversible Reaction:

A

6-phosphogluconolactone hydrolase

14
Q

Name the enzyme responsible for Step 3 of the Oxidative Irreversible Reaction:

A

6-phosphogluconate dehydrogenase

15
Q

Which steps within the HMP pathway are irreversible?

A

Steps 1-3: Oxidative Irreversible Reactions

  1. Dehydrogenation of Glucose 6-P
  2. Hydrolysis to 6-phosphogluconate
  3. Oxidative decarboxylation of 6-phosphogluconate
16
Q

Steps 4-8 of the HMP pathway are considered the

A

Nonoxidative Reversible Reactions

17
Q

Steps 4-8 are responsible for

A

Interconversions of sugar molecules

18
Q

Describe the Nonoxidative reversible reactions within HMP:

A
  • reversible steps
  • interconvert sugars w/3-7 C-atoms
  • permit synthesis of ribose 5-P used for nucleotide production
19
Q

The enzyme responsible for steps 4-8 of HMP is:

A

Transketolase

20
Q

This enzyme requires TPP from thiamine

A

Transketolase

21
Q

Transketolase is important for

A

diagnosing thiamine deficiency

22
Q

Name the functions of NADPH:

A
  1. Electron donor for the “reductive” biosynthesis of fatty acids, cholesterol, steroids
  2. Electron donor for neutralization of reactive oxygen species
  3. Provides reducing equivalents for Cytochrome P450 Monooxygenase system (for biosynthesis of steroids, detox xenobiotics)
  4. Play role in phagocytosis (destruction of pathogens by macrophages and neutrophils)
  5. Substrate for synthesis of nitric oxide (NO)
23
Q

When are reactive oxygen species produced?

A

During aerobic metabolism, through reactions with drugs and toxins, when levels of antioxidants are diminished

24
Q

____ is the major antioxidant system

A

Glutathion (GSH/GSSG)

25
Q

_____ is an enzyme that will incorporate 1 O-atom from molecular oxygen (creating -OH group) w/the other being reduced to H2O.

A

Monooxygenase

26
Q

Cyt P450 systems:

_____ system: the synthesis of steroids

A

Mitrochondrial

27
Q

Cyt P450 systems:

_____ system: detoxification of foreign compounds

A

Microsomal

28
Q

This Cyt P450 system is associated with the inner mitochondrial membrane.

A

Mitochondrial Cytochrome P450

29
Q

Mitochondrial Cytochrome P450 in the liver

A

uses the same system to synthesize bile acids and Vitamin D3

30
Q

Mitochondrial Cytochrome P450 in the kidney

A

converts vitamin D3 to its active form

31
Q

Mitochondrial Cytochrome P450 in steroidogenic tissues (placenta, ovaries, testes and adrenal cortex)

A

uses NADPH for synthesis of steroid hormones

32
Q

This Cyt P450 system is associated with the membranes of the smooth ER in liver cells

A

Microsomal system Cytochrome P450

33
Q

This system is responsible for the detoxification of drugs, toxins and other chemicals.

A

Microsomal System Cytochrome P450

34
Q

In the microsomal system cytochrome p450, by adding ____, the compound may be inactivated (or activated), made more soluble, or provide a reactive group for attachment of other molecules.

A

oxygen (hydroxyl groups)

35
Q

NADPH plays a role in phagocytosis within these cells

A

White Blood Cells (neutrophils and macrophages)

36
Q

NADPH role in phagocytosis:

-generates ______ that aid in killing microorganisms they have engulfed.

A

oxygen free radicals

37
Q

The MPO system is a combination of:

A

NADPH oxidase and myeloperoxidase

38
Q

The MPO system is used to

A

generate oxygen free radicals to aid in destruction of microorganisms

39
Q

Rare genetic NADPH oxidase deficiency causes

A

Chronic Granulomatous Disease (CGS)

40
Q

The granuloma in ____ is formed as a defense where the body attempts to “wall off” the collection of cells from the rest of the body

A

CGS: Chronic Granulomatous Disease

41
Q

CGS causes

A

persistent severe infections due to the inability to kill bacteria forming granulomas

42
Q

___ is synthesized from arginine, oxygen and NADPH

A

NO (Nitric Oxide)