Cell respiration is a process in which our cells use to transfer the energy in our food which contains glucose, into ATP (Adenosine Triphosphate). ATP is a special molecule that cells use during cellular respiration to extract energy. The following chemical equation summarizes the chemical changes that occur in cell respiration to glucose when oxygen is available. C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP There are 4 stages of cell respiration, the first major step is called glycolysis. Glycolysis is a 10-step series of reactions that splits a 6-carbon glucose molecule into two 3-carbon molecules called pyruvate. In glycolysis, 1 glucose molecule becomes 2 pyruvate and yields 2 ATP molecules (1 glucose → 2 pyruvate + 2 ATP).