Cellulose in Plants: Function, Structure & Quiz
All plants make the molecule cellulose. Not only is there more cellulose than any other organic molecule on Earth, but its unique structure lends itself to a wide variety of functions and products.
Building Blocks of Life
Plants may look very different on the outside, but if you take a closer look on the inside, all plants have some things in common. Plants are all made of polysaccharides, very large sugar molecules made of hundreds or thousands of single sugar units. Four common polysaccharides found in nature are starch, glycogen, chitin, and cellulose.
Cellulose is a very important polysaccharide because it is the most abundant organic compound on earth. Cellulose is a major component of tough cell walls that surround plant cells, and is what makes plant stems, leaves, and branches so strong. Next time you eat a salad, think about how much you have to chew it in order to be able to swallow all that plant material. It certainly takes a lot of work, and this is due in part to the structure of cellulose.
Imagine a bunch of long, thick ropes stuck together. This is very much what cellulose is like, but on a microscopic scale. Cellulose molecules are arranged parallel to each other, and are joined together with hydrogen bonds. This forms long, cable-like structures, which combine with other cellulose molecules, and is what produces such a strong support structure.
The rigid structure of cellulose is what allows plants to stand upright, and without the strength of cellulose, we wouldn't have lumber, paper, or cotton fabric. Because of its strength, cellulose is also used in a host of synthetic products such as carpeting, thickening agents in shampoo and suntan lotion, cosmetics, plastics (like your toothbrush handle), and other fabrics like rayon.
Cellulose also plays an important role in your diet. Most animals can't digest cellulose because it is so tightly linked together (unless you are a cow or a termite, in which case you have special microorganisms in your stomach to break the strong hydrogen bonds). When you eat cellulose it passes right through your digestive system without getting broken down, and this is called insoluble fiber. Insoluble fiber is very important in your diet because even though you don't get nutrition directly from the cellulose, it does contribute to digestive tract health by keeping everything moving.
Cellulose is an important organic molecule because its strong structure provides a wide variety of functions. From natural support and synthetic materials to digestive assistance, it's no wonder cellulose is the most common organic compound on our planet.
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