Glycolysis

Glycolysis is the sequence of reactions that converts glucose into pyruvate with the concomitant production of a relatively small amount of ATP. 

In aerobic organisms, glycolysis is the prelude to the citric acid cycleand the electron transfer chain. 

Under aerobic conditions, pyruvate is oxidesed to CO₂ and H₂O. If the supply of oxygen in is insufficient pyruvate is converted into lactate. 

Under anaerobic conditions, pyruvate is transformed to ethanol.

Net reaction:

Glucose + 2 ADP + 2 Phosphate +2 NAD⁺ ® 2 Pyruvate + 2 ATP + 2NADH + 2H⁺ + 2H₂O

                                     ®                      

                         Glucose                                                             pyruvic acid