glycan metabolism cellulose metabolism pathway UPa:UPA00692 GO:0030243 Metabolism of cellulose, the most abundant biopolymer on earth, recognized as the major component of plant biomass but also representative of microbial extracellular polymers. Bacterial cellulose (BC) belongs to specific product of primary metabolism and is mainly a protective coating, whereas plant cellulose (PC) plays a structural role. Cellulose is an unbranched polymer of beta-1-4 linked glucopyranose residues Plant cellulose and bacterial cellulose have the same chemical structure, but different physical and chemical properties.