Glycolysis is the reaction sequence used by almost all life forms to break down glucose molecules into pyruvate. The ubiquity of glycolysis is evidence of the common descent of living creatures from primitive cells in the far distant past. In eukaryotic cells, glycolysis takes place in the cytosol, unlike the citric acid cycle and the processes of the electron transport system, which take place in the mitochondria. This distinction has appeared on many MCATs.

Many significant organic reaction types occur in glycolysis. Reactions involving phosphate groups in glycolysis are phosphate transfers and shifts. Isomerization via keto-enol tautomerism as well as aldol cleavage (splitting a carbon-carbon bond by the reverse reaction to aldol condensation) are important reactions of aldehydes and ketones occurring in glycolysis. Formation of an alkene by dehydration of an alcohol occurs in glycolysis.