Question

The Warburg effect refers to the seemingly paradoxical preference for glycolysis over oxidative phosphorylation in many cancer tissues. After reading the incomplete statement shown below that reflects this paradox, fill in the blanks with appropriate numbers of ATP molecules and explain how you came up with the numbers by identifying glycolytic reactions that are key consuming or generating ATP.

“Glycolysis consumes __ ATP (per one glucose molecule) early in the pathway, produces __ ATP later, and the net of ___ ATP per glucose is significantly less than 26-28 ATPs produced by oxidative phosphorylation.”

Answer 1

Glycolysis is the process of metabolism of sugars in the cells. This process is divided into two phases, preparatory phase and pay-off phase. The glycolytic pathway consumes ATP in the preparatory phase and generates ATP in the pay-off phase. Studies have very well established that the preparatory phase of glycolysis consumes 2 molecules of ATP per single molecule of glucose metabolised. Similarly, the 4 moelcules of ATP are re-synthesized in the pay-off phase of glycolysis. Thus, the net ATP produced will be given by 4-2= 2.

Thus, the correct answers are:

Glycolysis consumes 2 ATP (per one glucose molecule) early in the pathway, produces 4 ATP later, and the net of 2 ATP per glucose is significantly less than 26-28 ATPs produced by oxidative phosphorylation