Refer to Figure 9.1 to answer the following questions.
Figure 9.1 illustrates some of the steps (reactions) of glycolysis in their proper sequence. Each step is lettered. Use these letters to answer the questions.

-The free energy for the oxidation of glucose to CO₂ and water is -686 kcal/mole and the free energy for the reduction of NAD+ to NADH is +53 kcal/mole. Why are only two molecules of NADH formed during glycolysis when it appears that as many as a dozen could be formed?

Question

Refer to Figure 9.1 to answer the following questions.
Figure 9.1 illustrates some of the steps (reactions) of glycolysis in their proper sequence. Each step is lettered. Use these letters to answer the questions.
 
-The free energy for the oxidation of glucose to CO₂ and water is -686 kcal/mole and the free energy for the reduction of NAD+ to NADH is +53 kcal/mole. Why are only two molecules of NADH formed during glycolysis when it appears that as many as a dozen could be formed?

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 because most of the energy is still stored in pyruvate and will be used in the later stages of cellular respiration to produce more ATP. Additionally, while glycolysis is not the most efficient reaction, much of the energy released as heat is still captured as ATP.