The free energy for the oxidation of glucose to CO₂ and water is -686 kcal/mol, and the free energy for the reduction of NAD⁺ to NADH is +53 kcal/mol. Why are only two molecules of NADH formed during glycolysis when it appears that as many as a dozen could be formed?
A) Most of the free energy available from the oxidation of glucose is used in the production of ATP in glycolysis.
B) Glycolysis is a very inefficient reaction, with much of the energy of glucose released as heat.
C) Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis.
D) There is no CO₂ or water produced as products of glycolysis.

Question

Quizplus · Accepted Answer

Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis. Only two molecules of NADH are formed during glycolysis because the rest of the free energy is still stored in pyruvate. In order to extract this energy, further reactions like aerobic respiration and the Krebs cycle are needed.

The Free Energy for the Oxidation of Glucose to CO₂