Mod4

Question 1

Role of the Pentose phosphate pathway

Answer 1

• produce NADPH
• generate ribose-5-phosphate (a five carbon sugar, name of the pathway) - sugar component for nucleotides (DNA and RNA)

Question 2

Currency of reducing power for most reductive biosynthetic reactions

Answer 2

NADPH

Question 3

Starting point of the pathway

Answer 3

Glucose 6 P

(Interconnects PPP w glycolysis)

Question 4

PPP carried out in the ____

Answer 4

Cytosol

Question 5

Equivalent of PPP in plants (to make NADPH)

Answer 5

Photosynthesis

(In animals, PPP active in tissues where the synthesis of biomolecules occurs at high rates)

Question 6

Oxidative phase

Answer 6

G6P gets oxidized and NADPH is produced (NADP+ reduced)

• G6P —> 6-Phosphogluconolactone —> 6-Phosphogluconate —> Ribulose-5-Phosphate + CO2
• Enzymes:
  (1) G6P Dehydrogenase: oxidized G6P, NADP+ reduced to NADPH

(2) Lactonase

(3) 6-phosphogluconate dehydrogenase: another NADPH produced

Question 7

Non oxidative phase

Answer 7

• Ribulose-5-P converted to Ribose-5-P
• interconversion of 3-, 4-, 5-, 6-, and 7-carbon sugars (a way for the excess 5 carbon sugars to be converted to glycolysis intermediates)
• no NADPH formed

Question 8

Second major product of the pathway

Answer 8

Ribose-5-P

Question 9

Number of NADPH produced for every G6P entering the ppp pathway

Answer 9

2

Question 10

Ribulose-5-P

Answer 10

5 carbon sugar, end product of the oxidative phase

Question 11

What enzyme converts ribulose5P to Ribose5P

Answer 11

Phosphopentose isomerase