Although the path of one glucose molecule through glycolysis generates a total of four ATP molecules, there is a net gain of only two ATP for each glucose molecule that enters the pathway. Why does the passage of one glucose molecule through glycolysis have a payoff of only two ATP molecules sapling

Glucose is energy rich compound which does not react easily. therefore to obtain the bond energy lodge in glucose (inform if ATP, energy in form of ATP must first be used breakdown each molecule of glucose to produce;

1. glucose phosphate=fructose phosphate.

2. fructose biphophate. This compound breaks down to give triose phosphate. This will be dehydrogenared by NAD to give intermediate that gives pyruvate.

Summary:the high stability of glucose energybonds-glycosidic bonds required the borrowing of 2ATPs to break it down before ATPs synthesis can commence.

Therefore from the Net 4ATPs, produced; 2ATPs must be deducted.