PPP

Question 1

Pentose Phosphate Pathway
• Also called the

Answer 1

HEXOSE MONOPHOSPHATE SHUNT or the PHOSPHOGLUCONATE PATHWAY

Question 2

PPP Functions:
1. To generate reducing power in the form of __
2. To generate pentoses from __ (D-ribose-5-P)
3. To convert excess pentoses back to hexoses
for oxidation via glycolysis

Answer 2

NADPH
hexoses

Question 3

Pentose Phosphate Pathway
• Occurs in the

Answer 3

cytosol of cells

Question 4

Two Products of PPP

Answer 4

NADPH and Ribose-5-P

Question 5

Required in the synthesis of nucleic acids
especially in actively dividing cells

Answer 5

Ribose-5-P

Question 6

• Phosphorylated NADH but the two are not interconvertible
• Used in REDUCTIVE BIOSYNTHESIS (eg. synthesis of lipids and nucleotides) and in DETOXIFICATION PROCESSES

Answer 6

NADPH

Question 7

Stages of PPP

Answer 7

Oxidative Stage and Non-oxidative Stage

Question 8

Oxidative generation of NADPH

Answer 8

Oxidative Stage

Question 9

• Interconversion of 3, 4, 5, 6 and 7-carbon sugars that results in the synthesis of 5-C sugars
• Serves as link of PPP to glycolysis

Answer 9

Non-oxidative Stage

Question 10

Main regulatory step in PPP

Answer 10

Oxidative Stage: Reaction 1

Question 11

Hydrolysis of the lactone to yield carboxylate

Answer 11

Oxidative Stage: Reaction 2

Question 12

Oxidative decarboxylation to yield ribulose-5-P
and CO2

Answer 12

Oxidative Stage: Reaction 3

Question 13

catalyzes transfer of three-carbon units

Answer 13

Transaldolase

Question 14

Rearrangements of C skeletons

Note that the reactions are REVERSIBLE

Answer 14

ribose-5-P ⇌ 2 fructose-6-P + glyceraldehyde-3-P

Question 15

Overall Reaction of the PPP

Answer 15

6 NADPH,H+ + 3 CO2 + 2 FRUCTOSE-6-P
+ Glyceraldehyde-3-P

Question 16

Both NADPH and Ribose-5-P are needed

Only the oxidative phase is active

Answer 16

Mode 1

Question 17

Only Ribose-5-P is needed

Answer 17

Mode 2

Question 18

• In actively dividing cells
• Reverse of the non-oxidative stage
• 2C6 + C3 ⇌ 3C5

Answer 18

Mode 2

Question 19

Only NADPH is needed

Answer 19

Mode 3

Question 20

• In adipose tissues for synthesis of fatty acids
• Both oxidative and non-oxidative phases are active

Answer 20

Mode 3

Question 21

NADPH is generated in the oxidative
phase, ribose-5-P enters the non-oxidative
phase for re-generation of Glc-6-P

Answer 21

Mode 3

Question 22

g-glutamylcysteylglycine (__ form)

Answer 22

reduced

Question 23

Essential for maintaining the normal structure of red blood cells (iron is maintained in the FERROUS STATE)

• Detoxifies reactive oxygen species (peroxides)

Answer 23

Glutathione

Question 24

Insufficient production of NADPH which results
eventually into insufficient __

Answer 24

GSH Glc-6-P

Question 25

• Cells cannot fight oxidative stress • Cells are susceptible to HEMOLYSIS (HEMOLYTIC ANEMIA)

Answer 25

Glc-6-P dH Deficiency