Cell wall The primary cell wall of land plants is composed of the polysaccharides cellulose, hemicelluloses and pectin. Often, other polymers such as lignin, suberin or cutin are anchored to or embedded in plant cell walls. Algae possess cell walls made of glycoproteins and polysaccharides such as carrageenan and agar that are absent from land plants. In bacteria, the cell wall is composed of peptidoglycan. The cell walls of archaea have various compositions, and may be formed of glycoprotein S-layers, pseudopeptidoglycan, or polysaccharides. Fungi possess cell walls made of the N-acetylglucosamine polymer chitin. Unusually, diatoms have a cell wall composed of biogenic
Cellulose synthase (UDP-forming) Cellulose synthase (UDP-forming) In enzymology, a cellulose synthase (, "UDP-glucose:(1→4)-β--glucan 4-β--glucosyltransferase") is an enzyme that catalyzes the chemical reaction Thus, the two substrates of this enzyme are UDP-glucose and [(1→4)-β--glucosyl], whereas its two products are UDP and [(1→4)-β--glucosyl]. This enzyme is involved in the synthesis of cellulose. A similar enzyme utilizes GDP-glucose, cellulose synthase (GDP-forming) (EC 2.4.1.29). Cellulose is an aggregation of unbranched polymer chains made of β-(1→4)-linked glucose residues that makes up a large portion of primary and secondary cell walls. Although important for plants, it is also synthesized by most algae, some bacteria, and some animals. Worldwide, 2