During the glycolytic pathway, 1,3 bisphosphoglycerate is converted into three phosphoglycerate and released phosphate yields one molecule of ATP.  In another step, phosphoenolpyruvate is converted into pyruvate and forms the second molecule of ATP. These two steps take place two times in glycolysis. Hence, four molecules of ATP are synthesized. The steps such as conversion of glucose to glucose-6 phosphate and fructose-6  phosphate to fructose-1, 6 bisphosphate consumed two molecules of ATP. Thus net gain of ATP molecules in glycolysis is 2.