Question

Oxidation of one molecule of glucose in aerobic respiration results in the production of

• A. 36 ATP molecules.
• B. 38 ATP molecules.
• C. 3 ATP molecules.
• D. Both A or B.

Answer 1

The correct option is B 38 ATP molecules.

The glucose molecule is first broken down into two molecules of pyruvic acid through glycolysis. The glycolysis results in production of net 2 ATP molecules and 2 molecules of reduced coenzyme $NADP{H}_2$. The 2 molecules of pyruvic acid are oxidatively decarboxylated by pyruvate dehydrogenase to yield two molecules of acetyl coenzyme and simultaneous production of two molecules of reduced coenzyme $NAD{H}_2$ one per conversion of pyruvic acid to acetyl CoA. The acetyl CoA enters Krebs cycle. Each moleucle of acetyl CoA that enters Krebs cycle generates 3 molecules of $NAD{H}_2$, 1 molecules of $FAD{H}_2$ and 1 molecule of GTP. Thus for two molecules of acetyl CoA from one glucose molecule, the net gain is 6 molecules of $NAD{H}_2$ and 2 molecules of $FAD{H}_2$ and 2 molecules of GTP. Assuming that one molecule of $NAD{H}_2$ is equivalent to 3 molecules of ATP and one molecule of $FAD{H}_2$ is equivalent to 2 molecules of ATP and one molecule of GTP is equivalent to one molecule of ATP. The net gain from entire aerobic breakdown of glucose comes out to be 38 molecules of ATP.