Pentose Phosphate Pathway Flashcards Preview

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Flashcards in Pentose Phosphate Pathway Deck (28):
1

What are the two phases of PPP

1. Oxidative; redox reactions catalized by enzymes called dehydrogenases to produce NADPH
2. Non -oxidative; recycling pathway

2

What are the major products form oxidative phase

1. Ribose 5-phosphate; for nucleotide synthesis
2. 2 NADPH; for biosynthetic reactions and antioxidant reducing power

3

what are the glycolytic intermediates from non oxidative pathway

1. glyceraldehyde 3-phosphate
2. fructose -6-phosphate

4

PPP has no ____production

energy; no ATP

5

PPP is a ____pathway

fermentative; no oxygen

6

The non oxidative pathway takes 1-ribose -5-phosphate and _____phosphate and rearranges back to _____to allow continuation of oxidative phase

1 xylulose 5-phosphate; glucose 6-phosphate

7

NOn oxidative phase is active only in tissues in which ____is needed in high amounts

NADPH

8

Where does PPP occur

All tissues; anywhere that requires a lot of ribose 5-phosphate for new DNA synthesis:-bone marrow, skin, oral and intestinal mucosa, tumors

9

Where is another place that PPP can occur

Anywhere that needs a lot of NADPH:
1. Tissues that are synthesizing fatty acids, cholesterol or steroid hormones - liver, adipose, adrnal cortex
2. Tissues that exposed to high levels of oxygen- erythrocytes, cornea and lens

10

1st step of PPP is rate limiting step where you convert glucose 6 phosphate to ____. NADP+ gets reduced to _____ and 6-phosphogluconate gets converted to _____

6-phosphogluconate (ends in -ate means you have acid; oxidizing glucose to an acid sugar);
NADH; ribulose 5-phosphate.

11

We need NADPH as a reducing agent for oxidative stress because

a lot of it comes from electron transport

12

What is glutathione (GSH)

3 aa compound that has sulfur group (cysteine) and forms disulfide bonds and donates H and reduce oxidized compounds. We have to regenerate the reduced form of glutathione in order to keep repairing oxidized tissues and to do this we need NADPH. It maintains the reduced form of glutathione that helps repair oxidized molecules.

13

What are the three aa that make up glutathione

glutamate, cysteine, glycine

14

The oxidative phase of PPP has ____steps. 2 involve _____reactions that produce _____

4; dehydrogenase; NADPH

15

The first step is the ____limiting step that forms the first ____.

rate; NADPH

16

The second step is an intermediate step that forms a _____. 6 phosphoglucanate is acted on by 6 phosphoglucanate dehydrogenase and form another ____ which becomes decarboxlyated. Then phosphopentose isomerase converts ketose to ____ and lose CO2 to form ribulose 5 phosphate

lactone; NADPH; aldehyde

17

What are the starting points of non oxidative phase

Ribose 5 phosphate and xylulose 5 phosphate

18

What is the intermediate step of non oxidative phase

Rearranging carbons to get intermediates that we can use

19

Xylulose 5-phosphate activates ____which activates PK2 to stimulate glycolysis

protein phosphatase 2A;

20

Which 2 enzymes transfer 2C or 3C ketose units to aldose acceptors

transketolase and transaldolase

21

transketolase requires ____ to transfer 2 C

thiamine

22

Which 2 enzymes are good intermediates to start the PPP pathway for the oxidative phase

1. Fructose 6-phosphate
2. Glyceraldehy 3-phosphate

23

What is Wernicke Korsakoff syndrome

Caused by a mutation in transketolase and severe deficiency in thiamine. It is common in alcoholics due to poor intestinal absorption of the vitamin.

24

High NADPH levels inhibit ____. This serves to make glucose 6-phosphate available for glycolysis.

glucose 6 phosphate dehydrogenase

25

What is the role of NADPH in the RBC

For repair of oxidative damage

26

When free radicals are produced it causes the production of ____ that can damage cell membranes and cause ___

peroxide; hemolysis (lyse) or hemolytic anemia

27

What does glucose 6 phosphate dehydrogenase deficiency cause

decreases intracellular NADPH and GSH

28

G6PDH deficiency protects against

malaria