Glycolysis is a central metabolic pathway responsible for the breakdown of glucose and plays a vital role in generating free energy for the cell and metabolites for further oxidative degradation. Glucose primarily becomes available in the blood as a result of glycogen breakdown or from its synthesis from noncarbohydrate precursors (gluconeogenesis) and is imported into cells by specific transport proteins. Glycolysis occurs in the cytoplasm and consists of 10 reactions, the net result of which is the conversion of 1 C6 glucose to 2 C3 pyruvate molecules. The free energy of this process is harvested to produce adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide hydride (NADH), key energy-yielding metabolites. The overall stoichiometry of the pathway is: glucose + 2 Pi + 2 ADP + 2 NAD+ > 2 pyruvate + 2 ATP + 2 NADH + 2 H+ + 2 H2O (H+: hydrogen ion, Pi: phosphate ion, NAD+: nicotinamide adenine dinucleotide).