pentose phosphate pathway

Question 1

other names for pentose phosphate pathway (PPP)

Answer 1

hexose monophosphate pathway

phosphogluconate pathway

pentose shunt

Question 2

oxidative phase makes NADPH - 3 reactions:

1.

2.

3.

Answer 2

1. glucose 6-Phosphate Dehydrogenase (glucose 6-P → lactone)
2. Lactonase is a hydrolase (opens ring by adding water)
3. 6-Phosphogluconate Dehydrogenase (resulting in ribulose 6-P)

Question 3

glucose 6-phosphate dehydrogenase:

1. ____ glucose 6-phosphate to form a ____
2. reduces ____ to form ____
3. ____ reaction

Answer 3

1. oxidizes lactone
2. NADP⁺ NADPH
3. rate-limiting

Question 4

lactonase:

is a ____ (opens the ring by adding ____ )

Answer 4

hydrolase water

Question 5

6-phosphogluconate dehydrogenase:

1. oxidative ____ of 6-phosphogluconate to form ____
2. reduces ____ to form ____

Answer 5

1. decarboxylation ribulose 5-phosphate
2. NADP⁺ NADPH

Question 6

oxidized forms of NADPH

Answer 6

NAD⁺

NADP⁺

Question 7

reduced forms of NADPH

Answer 7

NADH

NADPH

Question 8

NAD⁺ is the cofactor for most enzymes that act in the direction of substrate ____ ( ____ )

Answer 8

oxidation ( deydrogenases )

Question 9

NADPH functions as a cofactor for ____ , enzymes that catalyze substrate ____

Answer 9

reductases

reduction

Question 10

reduced metabolites – ( ____ ) –> oxidized metabolites

Answer 10

dehydrogenases (catabolism)

Question 11

oxidized metabolites – ( ____ ) –> reduced metabolites

Answer 11

reductases (anabolism)

Question 12

NADH (reduced) – ( ____ ) –> NAD⁺ (oxidized)

Answer 12

ETC and OXPHOS

Question 13

NADP⁺ (oxidized) – ( ____ ) –> NADPH (reduced)

Answer 13

pentose phosphate pathway

Question 14

ATP – ( ____ ) –> ADP

Answer 14

NAD⁺ kinase

Question 15

NADP⁺ – ( ____ ) –> NAD⁺

Answer 15

mitochondrial energy-linked transhydrogenase

Question 16

why do we need NADPH:

1. synthesis of ____
2. ____ power

Answer 16

1. monomers (biosynthesis: fatty acid, cholesterol, neurotransmitter, nucleotide)
2. reducing (detoxification- reduction of oxidized glutathione, cytochrome P450 monooxygenases)

Question 17

tissues with active pentose phosphate pathways:

Answer 17

adrenal gland (steroid synthesis)

liver (fatty acid and cholesterol synthesis)

testes (steroid synthesis)

adipose tissue (fatty acid synthesis)

ovary (steriod synthesis)

mammary gland (fatty acid synthesis)

Red blood cells (maintenance of reduced glutathione)

Question 18

NADPH is required to keep supply of ____

Answer 18

glutathione

Question 19

glutathione is a tripeptide, consisting of ____ , ____ , ____

Answer 19

glutamate, cysteien, glycine

Question 20

glutathione interacts with proteins (no enzyme needed), this is important because it can ____ or ____ disulfide bonds

Answer 20

create or destroy

Question 21

glutathione can ____ peroxides

Answer 21

inactivate

Question 22

reactive oxygen species:

1. maintain the redox ____ of cells
2. too much can ____ macromolecules

Answer 22

1. homeostasis
2. damage

Question 23

regeneration of reduced glutathione uses

Answer 23

NADPH

Question 24

glucose-6-phosphate-dehydrogenase deficiency 5 classes:

1.

2.

3.

4.

5.

Answer 24

1. chronic hemolytic anemia
2. acute hemolysis due to nomral levels of oxidant stress
3. acute hemolysis due to high levels of oxidant stress
4. normal function (60-90% activity)
5. normal function (too much G6PD activty)

Question 25

G6PD & Hemolytic Anemia:

RBCs are destroyed in ____/____ not months

Fe in heme must be ____ to bind O₂

Answer 25

hours/weeks

reduced

Question 26

most severe effect of G6PDD is ____ ____

Answer 26

neonatal jaundice

Question 27

G6PD and neonatal jaundice:

blood is normal but liver cannot ____ bilirubin

when bilirubin enters the brain (kernicterus), deafness, cerebral palsy, or ____ can result

Answer 27

conjugate

death

Question 28

G6PD:

1. monomer =
2. dimer =
3. tetramer =

Answer 28

1. inactive
2. active
3. active

Question 29

in patients with Ataxia Telangiectasia, HSP27 is ____

usually HSP27 promotes G6PD ____

without an active HSP27, G6PD cannot dimerize, therefor it is ____

Answer 29

inactive

dimerization

inactive

Question 30

G6PD regulation:

1. activators:
2. inhibitors:

Answer 30

1. dimerization; transcription factors for antioxidant genes; cell cycle and synthesis activators; insulin
2. phosphorylation; apoptosis-signaling proteins

Question 31

____ activates G6PD

Answer 31

insulin

Question 32

high external glucose concentration in the ____ cells results in decreased G6PD

Answer 32

pancreatic beta-islet

Question 33

PPP outputs:

1. NADPH
2. Energy (ATP)
3. Nucleotides:

Answer 33

1. primary product NADPH (run full PPP)
2. primary products: F-6-P and GA3P (runs into glycolysis)
3. primary product: ribose-5-P (run nonoxidative phase in reverse) OR primary product: ribose-5-P and NADPH (run oxidative phase only)