Chapter 9 - Glycolysis and the Pentose Phosphate Pathway

Abstract

Glycolysis, the central pathway of glucose metabolism, is conserved evolutionarily in all cells that use carbohydrates for energy metabolism. Glycolysis is a linear pathway of 10 enzymatic reactions in the cytosolic compartment that convert glucose, a six-carbon sugar, to two molecules of pyruvate, a three-carbon compound. It is not only a source of energy, but the intermediates in glycolysis are also starting points for other pathways in the cell, interfacing with amino acid, nucleic acid, and lipid metabolism. Glycolysis is presented from the perspective of the red blood cell, which is the only cell in the body that relies exclusively on glucose and glycolysis for energy metabolism. This chapter describes the enzymes, intermediates, and regulation of glycolysis, and it concludes with a presentation of the pentose phosphate pathway, a shunt from glycolysis that provides NADPH for antioxidant protection and biosynthetic reactions and ribose and deoxyribose for the synthesis of nucleotides, ribonucleic acid (RNA), and deoxyribonucleic acid (DNA).