The complete catabolism of each molecule of glucose produces 10 NADH in a normal

Question

The complete catabolism of each molecule of glucose produces 10 NADH in a normal mammalian cell. However, if there is no oxygen in the cell to dispose of the electrons after they traverse the electron transport chain, the NADH in the cytoplasm will be used to reduce pyruvate to lactate, regenerating NAD so that glycolysis can continue. What is the free energy of formation of lactate from NADH and pyruvate under standard conditions?

NAD+ + H+ +2e- èNADH

-0.32

Pyruvate + 2H+ 2e-è lactate

-0.185

1/2 O2 + 2H+ +2e- èH2O

0.816

As this reaction proceeds under anaerobic conditions, the lactate will gradually build up suppressing the reaction via Le Chatelier's principle. If the NADH and NAD concentrations are equal, at what [Lac]/[Pyr] ratio will this reaction no longer proceed?

A) ~10-5           B) ~37,000      C) ~230           D) close to infinite                  E) when they are equal ( 1 )

Explanation / Answer

Question is not clear to understand

Pyruvate + NADH --------LDH-------> Latate + NAD+ = -25.1 kJ/mole (standard free energy change)

Option A is true (10:1 ration for lacate to pyruvate)

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