The pentose phosphate pathway gets its name because it involves several intermediates that are phosphorylated five-carbon sugars (pentoses). This pathway provides monomers for many metabolic pathways by transforming glucose into the four-carbon sugar erythrose and the five-carbon sugar ribose; these are important monomers in many metabolic pathways. Many of the reactants in this pathway are similar to those in glycolysis, and both occur in cytosol. The ribose-5-phosphate can be transported into the nucleic acid metabolism, producing the basis of DNA and RNA monomers, the nucleotides. In meristematic cells, large amounts of DNA must be produced during the S-phase of a short cell cycle; this pathway is an extremely important part of the metabolism of these cells. In these cells, the pentose phosphate pathway is active and shifted in favor of ribose production.