Biochemistry: Pentose Phosphate Pathway

Front 1

What 3 things can form glucose 6-phosphate in one step?

Back 1

1. Glucose

2. Glucose 1-phosphate

3. Fructose 2,6-phosphate

Front 2

The pentose phosphate pathway is an important source of what?

Back 2

NADPH

Front 3

What 4 synthesis pathways need NADPH?

Back 3

1. Fatty acid biosynthesis

2. Cholesterol biosynthesis

3. Neutrotransmitter biosynthesis

4. Nucleotide biosynthesis

Front 4

What 2 detoxification pathways require NADPH?

Back 4

1. Reduction of Oxidized glutathione

2. Cytochrome P450 monooxygenases

Front 5

Back 5

NADPH

Notice the extra phosphate on 2' OH of adenine!

Front 6

NADPH is the source of what?

Back 6

Biosynthetic reducing power in ALL organisms

Front 7

The metabolism of what by the pentose phosphate pathway generates NADPH?

Back 7

Glucose 6-phosphate

Front 8

What are the 2 phases of the pentose phosphate pathway?

Back 8

1. The oxidative generation of NADPH

2. The nonoxidative interconversion of sugars

Front 9

In the oxidative phase, 2 NADPH is generated when what occurs?

Back 9

When glucose 6-phosphate is oxidized to ribulose 5-phosphate via glucose 6-phosphate dehydrogenase

Front 10

Glucose 6-phosphate to Ribulose 5-phosphate produces what?

Back 10

2 NADPH molecules and CO2!

Front 11

What are the 4 steps to make Ribulose 5-phosphate?

Back 11

1. Glucose 6-phosphate (START)

2. 6-phosphoglucono-lamda-lactone

3. 6-phospho-gluconate

4. Ribulose 5-phosphate

Front 12

How is Glucose 6-phosphate converted into 6-phosphoglucono-lamda-lactone?

Back 12

Glucose 6-phosphate dehydrogenase catalyzes the oxidation reaction of NADP+

Front 13

How is 6-phosphoglucono-lamda-lactone converted into 6-phospho-gluconate?

Back 13

Lactonase catalyzes the hydrolysis

Front 14

How is 6-phospho-gluconate converted into Ribulose 5-phosphate?

Back 14

6-phosphogluconate dehydrogenase catalyzes the oxidation reaction with NADP+

Front 15

What is it and where did it come from?

Back 15

6-Phosphoglucono-lamda-lactone is made from Glucose 6-phosphate via glucose 6-phosphate dehydrogenase.

Front 16

What is it and where did it come from?

Back 16

6-Phospho-gluconate is made from 6-Phosphoglucono-lamda-lactone via Lactonase.

Front 17

What is it and where did it come from?

Back 17

Ribulose 5-phosphate is made from 6-Phosphogluconate via 6-Phosphogluconate dehydrogenase.

Front 18

What converts Ribulose 5-phosphate into Ribose 5-Phosphate?

Back 18

Phosphopentose isomerase

Front 19

What 2 enzymes create a reversible link between the pentose phosphate pathway and glycolysis? How?

Back 19

Transketolase and transaldolase create a link by catalyzing 3 successive reactions

Front 20

3 pentose sugars can be made into what?

Back 20

2 hexose and 1 triose

Front 21

Transketolase and transaldolase create a link by catalyzing 3 successive reactions. What is the 1st one?

Back 21

Formation of Glyceraldehyde 3-phosphate and Sedoheptulose 7-phosphate from two pentoses via transketolase

Front 22

What forms Glyceraldehyde 3-phosphate and Sedoheptulose 7-phosphate via transketolase?

Back 22

Xylulose 5-phosphate and Ribose 5-phosphate

Front 23

Transketolase and transaldolase create a link by catalyzing 3 successive reactions. What is the 2nd one?

Back 23

Formation of Fructose 6-phosphate and Erythrose 4-phosphate via transaldolase

Front 24

How is Ribulose 5-phosphate converted to Xylulose 5-phosphate?

Back 24

Phosphopentose epimerase

Front 25

What forms Fructose 6-phosphate and Erythrose 4-phosphate via transaldolase?

Back 25

Glyceraldehyde 3-phosphate and Sedoheptulose 7-phosphate

Front 26

Transketolase and transaldolase create a link by catalyzing 3 successive reactions. What is the 3rd one?

Back 26

Formation of Fructose 6-phosphate and Glyceraldehyde 3-phosphate via Transketolase

Front 27

What forms Fructose 6-phosphate and Glyceraldehyde 3-phosphate via Transketolase?

Back 27

Erythrose 4-phosphate and Xylulose 5-phosphate

Front 28

Excess ribose 5-phosphate formed by the pentose phosphate pathway can be what?

Back 28

Completely converted into glycolytic intermediates

Front 29

In the number of C, list the nonoxidative phase reactions of the pentose phosphate pathway. Don't forget the enzymes!

Back 29

1. C5 + C5 <--> C3 + C7 (Transketolase)

2. C3 + C7 <--> C6 + C4 (Transaldolase)

3. C4 + C5 <--> C6 + C3 (Transketolase)

Front 30

What cofactor transfers 1-carbon units?

Back 30

Biotin!

Front 31

What are the 4 modes cells use the pentose phosphate pathway?

Back 31

1. Cells need ribose for nucleotides

2. Cells need NADPH for biosynthesis AND ribose for nucleotides

3. Cells need ONLY NADPH for biosynthesis

4. Cells need BOTH NADPH and ATP

Front 32

Why would cells need ribose 5-phosphate more than NADPH?

Back 32

If they are rapidly dividing, they need ribose to synthesize nucleotide precursors for DNA

Front 33

In Mode 1 of the Pentose Phosphate Pathway, what is the nonoxidative phase doing?

Back 33

Converting

2 molecules of Fructose 6-phosphate

and 1 molecule of glyceraldehyde 3-phosphate

into 3 molecules of ribose 5-phosphate.

Front 34

In Mode 2 of the Pentose Phosphate Pathway, what is the predominant reaction?

Back 34

The formation of 2 NADPH and 1 molecule of ribose 5-phosphate (by isomerization) from 1 glucose 6-phosphate.

The pathway essentially STOPS at the end of the oxidative phase.

Front 35

In Mode 3 of the Pentose Phosphate Pathway, what 3 things are occurring?

Back 35

1. Oxidative phase of the Pentose Phosphate Pathway

2. Non-oxidative phase

3. Gluconeogenesis of glucose 6-phosphate from fructose 6-phosphate and glyceraldehyde 3-phosphate.

Front 36

In Mode 4 of the Pentose Phosphate Pathway, what happens?

Back 36

Fructose 6-phosphate and glyceraldehyde 3-phosphate derived from the non-oxidative phase enter the glycolytic pathway to form ATP.