Question

Net gain of ATP in glycolysis
(a) 6
(b) 2
(c) 4
(d) 8

Answer 1

Hint: 4 ATPs are produced and 2NADPH are produced in glycolysis. Each NADPH gives 3 ATP molecules. 2 ATPs are utilized in the glycolysis.

Complete step by step answer:
Glycolysis is the sequence of 10 enzyme-catalyzed reactions that converts glucose into pyruvate with the production of ATP.
2ATPs utilized in the initial steps of glycolysis:
1ATP utilized during the conversion of glucose to glucose- 6-phosphate and 1 ATP utilized during the conversion of fructose-6-phosphate to fructose 1,6 bisphosphate.

During the conversion of 1,3disphosphoglycerate to 3-phosphoglycerate, 2 ATPs released during the conversion of phosphoenolpyruvate to pyruvate 2 ATPs released. In the entire process of glycolysis, 2 NADPH molecules also formed. Each NADH produces 3ATP molecules that mean 6 ATP molecules in glycolysis are produced via NADPH. Therefore the total ATP molecules formed are 10ATP as 2ATPs used up in the initial steps, the net gain is 8 ATP molecules.
So, the correct answer is ‘8’.

Additional information:
Glycolysis is also called the EMP pathway. EMP stands for Embden- Meyerhof- Parnas so it is also called "the Embden-Meyerhof-Parnas" pathway.
It is a unique pathway that occurs both aerobically and anaerobically.
End products of the aerobic pathway and the anaerobic pathways are pyruvate and lactate.
Two substrate-level phosphorylation one is during the conversion of 1,3 bisphosphoglyceric acid to 3- phosphoglyceric acid where 2ATPs are released and second, substrate- level phosphorylation occurs during the conversion of phosphoenolpyruvate to pyruvic acid which gives 2ATPs.

Note: Glycolysis has two phases:
- Phase I: Preparatory phase, Phase II: payoff phase
- 2ATPs consumed in phase I, and 8 ATPs are produced in phase II.