Question

Which is the major factor(s) determining whether glucose is oxidized by aerobic or anaerobic glycolysis?

• A. Presence of high AMP
• B. NADH and the ATP/ADP ratio
• C. Ca\(^2\)
• D. FADH\(_2\)

Hint:

When oxygen is available, NADH is used in the electron transport chain for efficient ATP production, supporting aerobic glycolysis. Without oxygen, NADH is used in lactate production, favoring anaerobic glycolysis.

Answer 1

The Correct Option is B

The major factors determining whether glucose is oxidized via aerobic or anaerobic glycolysis are the NADH levels and the ATP/ADP ratio.

(1) NADH and ATP/ADP Ratio:
- In aerobic conditions, NADH produced during glycolysis is reoxidized in the electron transport chain, which requires oxygen. The ATP produced is highly efficient.
- In anaerobic conditions, when oxygen is unavailable, NADH is reoxidized by converting pyruvate to lactate, allowing glycolysis to continue but with less ATP production. The ATP/ADP ratio helps regulate this by signaling the cell's energy status.

(2) Why Other Options Are Incorrect:
- Presence of high AMP (Option 1) affects energy regulation but is not the determining factor between aerobic and anaerobic glycolysis.
- Ca\(^2\) (Option 3) plays a role in muscle contraction and other processes but is not a primary factor in determining the pathway of glucose oxidation.
- FADH\(_2\) (Option 4) is involved in the electron transport chain but does not directly determine whether glucose follows aerobic or anaerobic glycolysis.

Conclusion: The major determinants of whether glucose is oxidized via aerobic or anaerobic glycolysis are the NADH levels and the ATP/ADP ratio within the cell.