Question

The reduction of NAD+ to NADH (and H+) occurs both in the ________ and in the ________ of the ________.

a. Nucleotide synthesis
b. Glycolysis
c. Citric acid cycle
d. Electron transport chain

Answer 1

The reduction of NAD+ to NADH occurs in glycolysis and the citric acid cycle, stages of cellular respiration that contribute to ATP synthesis and involve various redox reactions.

Step-by-step explanation:

The reduction of NAD+ to NADH (and H+) occurs both in the glycolysis and in the citric acid cycle of the cellular respiration. In glycolysis, the process of glucose breakdown involves the oxidation of glucose and the coinciding reduction of NAD+ to NADH. This process results in the production of 2 molecules of NADH and 2 net molecules of ATP. After pyruvate is produced, it enters the mitochondria where it is further metabolized in the citric acid cycle, also known as the Krebs cycle. In this cycle, additional NADH is produced along with ATP and carbon dioxide. The NADH and FADH2 generated in these processes then donate electrons to the electron transport chain, which is part of oxidative phosphorylation, ultimately leading to the synthesis of a significant amount of ATP.