As a joke, you have decided to give Kevin a batch of cookies containing an inhib

Question

As a joke, you have decided to give Kevin a batch of cookies containing an inhibitor of some enzyme associated with metabolism. After eating these cookies, Kevin finds that only 34 moles of ATP are being produced per mole of lactose.

a) Show all the work for the ATP calculation.

b) Where does the inhibitor act? Name the enzyme that is in inhibited and the pathway with which it is usually associated.

*Choose from enzymes in glycolysis, pyruvate dehydrogenase complex, and the TCA cycle. Assume electron transport and oxidative phosphorylation pathways are unaffected.

Explanation / Answer

a)

For 1 lactose molecule through glycolysis:

Step ATP running total

Hexokinase -2 -2

Phosphofructokinase -2 -4

GAPDH +10 +6

Phosphoglycerate kinase +4 +10

Pyruvate kinase +4 +14

For the 4 pyruvates

4 pyruvate dehydrogenase (NADH) +10 +24

4 Isocitrate Dehydrogenase (NADH) +10 +34

4 -ketoglutarate dehydrogenase (NADH) +10

4 Succinyl-CoA synthetase (GTP) +4

4 Succinate Dehydrogenase (FADH2) +6

4 Malate Dehydrogenase (NADH) +10

TOTAL 64

b) The inhibitor must act at -ketoglutarate dehydrogenase, which is part of the TCA cycle.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.