glycan metabolism glycan biosynthesis Biosynthesis of glycan (polysaccharide) polymers. Glycan may also be used to refer to the carbohydrate portion of a glycoconjugate, such as a glycoprotein or a proteoglycan. Glycans usually consist solely of O-glycosidic linkages of monosaccharides (cellulose is a glycan composed of beta-1,4-linked D-glucose; chitin is a glycan composed of beta-1,4-linked N-acetyl-D-glucosamine). Glycans can be homo or heteropolymers of monosaccharide residues, and can be linear or branched. GO:0000271 pathway polysaccharide biosynthesis UPa:UPA00484