Final answer:
Glycolysis starts with one molecule of glucose and ends with the net production of two ATP molecules and two molecules of NADH, in addition to generating two molecules of pyruvate. Two ATP molecules are invested initially, but four ATPs are produced through the stages, thus leading to a net gain. Pyruvate may then enter further stages of cellular respiration if conditions allow.
Step-by-step explanation:
The Overall Results of Glycolysis
The process of glycolysis begins with the input of one molecule of glucose and ends with several key products. Initially, two ATP molecules are used to invest energy into the breakdown of glucose. During this process, the glucose is split into two three-carbon molecules known as pyruvate. Throughout the subsequent steps of glycolysis, energy is released which results in the production of four ATP molecules and two NADH molecules. However, considering that two ATPs were already used at the start, the net gain is two ATP molecules and the two NADH molecules remain constant. Thus, the complete glycolysis cycle yields a net gain of two ATP molecules, two NADH molecules, and two pyruvate molecules from one glucose molecule.
If under anaerobic conditions the cell cannot process pyruvate further via the Krebs cycle and electron transport chain, then glycolysis is the primary source of ATP production and only two ATP molecules will be gained from one molecule of glucose.