Cellulose - Structure Of Cellulose, How Cellulose Is Arranged In Plant Cell Walls, Cellulose Digestion
Cellulose is a substance found in the cell walls of plants. Although cellulose is not a component of the human body, it is nevertheless the most abundant organic macromolecule on Earth. The chemical structure of cellulose resembles that of starch, but unlike starch, cellulose is extremely rigid (Figure 1). This rigidity imparts great strength to the plant body and protection to the interiors of plant cells.
Figure 1. The structure of cellulose. Illustration by Hans & Cassidy. Courtesy of Gale Group.
Additional Topics
Like starch, cellulose is composed of a long chain of at least 500 glucose molecules. Cellulose is thus a polysaccharide (Latin for "many sugars"). Several of these polysaccharide chains are arranged in parallel arrays to form cellulose microfibrils. The individual polysaccharide chains are bound together in the microfibrils by hydrogen bonds. The microfibrils, in turn, are bundled t…
Like human bone, plant cell walls are composed of fibrils laid down in a matrix, or "background" material. In a cell wall, the fibrils are cellulose microfibrils, and the matrix is composed of other polysaccharides and proteins. One of these matrix polysaccharides in cell walls is pectin, the substance that, when heated, forms a gel. Pectin is the substance that cooks use to make jel…
Humans lack the enzyme necessary to digest cellulose. Hay and grasses are particularly abundant in cellulose, and both are indigestible by humans (although humans can digest starch). Animals such as termites and herbivores such as cows, koalas, and horses all digest cellulose, but even these animals do not themselves have an enzyme that digests this material. Instead, these animals harbor microbes…
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