Final answer:
In the process of glycolysis, four gross ATP molecules are produced when one glucose molecule is converted into two pyruvate molecules. However, the net gain for the cell is two ATP molecules after consuming two ATPs initially.
Step-by-step explanation:
The process of glycolysis involves the conversion of one molecule of glucose into two molecules of pyruvate. During this metabolic pathway, a gross total of four ATP molecules are produced. However, two ATP molecules are consumed in the early stages of glycolysis, resulting in a net gain of two ATP molecules for the cell from one glucose molecule.
In addition to ATP, glycolysis also generates two NADH molecules. If oxygen is not present or if the cell lacks mitochondria, the pyruvate may be fermented; otherwise, it proceeds to the Krebs cycle for further processing and energy extraction. However, the question specifically asks about the gross number of ATP molecules produced in glycolysis, which is four.