Glycolysis, the major pathway for glucose metabolism, occurs in the cytosol of all cells. However, oxidization of glucose beyond pyruvate (the end product of glycolysis) requires both oxygen and mitochondrial enzyme systems: the pyruvate dehydrogenase complex, the citric acid cycle, and the respiratory chain. Ref: Bender D.A., Mayes P.A. (2011). Chapter 18. Glycolysis & the Oxidation of Pyruvate. In D.A. Bender, K.M. Botham, P.A. Weil, P.J. Kennelly, R.K. Murray, V.W. Rodwell (Eds), Harper's Illustrated Biochemistry, 29e.