In biochemistry, the pentose phosphate pathway (also called the phosphogluconate pathway and thehexose monophosphate shunt) is a metabolic pathway parallel to glycolysis that generates NADPH andpentoses (5-carbon sugars) as well as Ribose 5-phosphate, a precursor for the synthesis of nucleotides. While it does involve oxidation of glucose, its primary role is anabolic rather than catabolic. There are two distinct phases in the pathway. The first is the oxidative phase, in which NADPH is generated, and the second is the non-oxidative synthesis of 6-carbon sugars. For most organisms, the pentose phosphate pathway takes place in the cytosol; in plants, most steps take place in plastids.