Cell wall for higher growth rates in diatoms. In brown algae, phlorotannins may be a constituent of the cell walls. The group Oomycetes, also known as water molds, are saprotrophic plant pathogens like fungi. Until recently they were widely believed to be fungi, but structural and molecular evidence has led to their reclassification as heterokonts, related to autotrophic brown algae and diatoms. Unlike fungi, oomycetes typically possess cell walls of cellulose and glucans rather than chitin, although some genera (such as "Achlya" and "Saprolegnia") do have chitin in their walls. The fraction of cellulose in the walls is no more than 4
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