Pentose Phosphate Pathway

Question 1

Starting Molecule

Answer 1

Glucose-6-Phosphate (Made at start of glycolysis by hexokinase)

Question 2

Pentose Phosphate IMPORTANT Functions:

Answer 2

Produce NADPH
Produce 5 Carbon sugars for synthesis of nucleotides

Question 3

Key Regulatory Enzyme:

Answer 3

Glucose-6-Phosphate-Dehydrogenase

Question 4

Activity of Glucose-6-Phosphate Dehydrogenase (G6PD) controlled by

Answer 4

NADP+/NADPH Ratio
NADPH INHIBITS
NAD+ STIMULATES (Need more NADPH to be made)

Question 5

What causes G6PD to be deficient

Answer 5

X linked gene defect
Point mutation on Glucose-6-Phosphate Dehydrogenase Gene

Question 6

Consequence of LOW G6PD

Answer 6

Pentose-Phosphate pathway ceases
Low Levels of NADPH in cells

Question 7

Why is low levels of NADPH bad?

Answer 7

Needed to recycle GSH (Glutathione) back into its active reduced form

Question 8

GSH general importance

Answer 8

ANTIOXIDANT
Protects from oxidative damage from ROS

Question 9

RBCs very affected by Glucose-6-Phosphate Dehydrogenase Deficiency because

Answer 9

Have no mitochondria (Pentose-Phosphate Pathway only source of NADPH)

Carry oxygen so exposed to lots of ROS

Question 10

Consequence of G6PD Deficiency to RBCs

Answer 10

Low NADPH So Low Active GSH
Vulnerable to ox damage
ROS cause haemoglobin to be cross linked by inappropriate disulphide bonds
Forms Insoluble Heinzbodies
Causes affected RBCs to undergo haemolysis