Cellulose
Say it: SEL-yuh-lohs
Cellulose is a strong, unbranched polysaccharide of glucose units joined by beta 1-4 bonds and the main structural material of plant cell walls.
Definition
What is cellulose?
No organic compound on Earth is more abundant than cellulose. It is a polysaccharide: a long, straight chain of hundreds to many thousands of glucose molecules joined by beta 1-4 glycosidic bonds. In this linkage each glucose unit is turned over relative to its neighbors, which keeps the chain flat and extended. Parallel chains bind to one another through many hydrogen bonds, forming crystalline microfibrils with great tensile strength.
Plants make cellulose at the cell surface, where rosette-shaped cellulose synthase complexes in the plasma membrane spin out microfibrils that become embedded in a matrix of hemicellulose and pectin; in wood, lignin is added as well. This framework lets plant cells withstand their internal water pressure and lets trees stand tall. Some bacteria, algae and tunicates also make cellulose. Starch is a glucose chain too, but its alpha links make it coil and easy for animals to digest. Human enzymes cannot break the beta bonds, so cellulose passes through the gut as insoluble dietary fiber that adds bulk, while cows, termites and other plant eaters rely on gut microbes that make the enzyme cellulase.
Cotton is almost pure cellulose, and wood pulp is the raw material for paper, cellophane and rayon.
Word parts
Where does the word “cellulose” come from?
- cellul-
- small room, cellLatin cellula
- -ose
- suffix naming a sugarFrench -ose, as in glucose
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Terms that go with it
- GlucoseGlucose is a six-carbon simple sugar, C6H12O6, that serves as the main fuel for most cells and is the sugar carried in human blood.
- CarbohydrateA carbohydrate is a sugar or a chain of sugars, such as starch or cellulose, built from carbon, hydrogen and oxygen and used for energy and structure.
- Cell wallA cell wall is a rigid layer outside the plasma membrane of plant, fungal, algal and most bacterial cells that gives shape and stops them bursting.
- Dietary fiberDietary fiber is the part of plant foods, mostly carbohydrate, that human digestive enzymes cannot break down, so it reaches the large intestine intact.
- Hydrogen bondA hydrogen bond is a weak attraction between a slightly positive hydrogen atom, bonded to oxygen or nitrogen, and a nearby electronegative atom.
- ChitinChitin is a tough, nitrogen-containing polysaccharide built from N-acetylglucosamine units that forms arthropod exoskeletons and fungal cell walls.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- OpenStax Biology 2e, 3.2 Carbohydrates
- Li, Bashline, Lei and Gu, Cellulose Synthesis and Its Regulation (The Arabidopsis Book, 2014)
- NCBI MeSH: Cellulose
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