Question

Explain how in glycolysis that the splitting of one glucose molecule results in 4 ATP but there is only a net gain of 2 ATP.

Answer 1

In order to make ATP, you have to spend ATP. So Glycolysis need 2 ATP to break down the glucose, which results in 4 ATP, but a net gain of 2 ATP.
For example, if you want to start selling cookies, you first have to put in some money for supplies,right? Lets say supplies are $2. Then you sell your cookies and get $4, but not really, because the $2 was used for supplies

Answer 2

The energy balance of the glycolysis itself is as follows:

* Transformation of glucose into glucose-6-phosphate consumes 1 ATP;

* The conversion of fructose-6-phosphate to 1,6-fructose bisphosphate consumes 1 ATP;

* Transformation of 3-phospho-D-glycerate (x2) into 2-phospho-D-glycerate (x2) produces 2 ATP;

* The conversion of phosphoenolpyruvate (x 2) to pyruvate (x 2) produces 2 ATP.

Conclusion :

* The transformation of a molecule of glucose into two molecules of pyruvate is accompanied by a gain of two molecules of ATP.