The Cholesterol Page
This is just a quick intro to explain something farther down on the page. The Fluid Mosaic model refers to the phospholipids in a membrane being able to move freely. This makes the membrane more fluid, like a soap bubble; the outside is constantly moving and changing. The "fluidity" of the membrane on this page refers to that.
An important molecule found in the cell membrane is the cholesterol molecule. Cholesterol provides stability to the membrane by decreasing its fluidity. Because the phospholipids are constantly moving, the membrane isn't very rigid by itself. Cholesterol limits movement of phospholipids to keep the membrane more stable. Doing the opposite of what cholesterol does are molecules of unsaturated fatty acids, which INCREASE membrane fluidity. Experiments have shown that membrane fluidity could be linked to metabolism and lifespan, but this hasn't been completely proved. For example, animals like birds have a fast metabolism but a short lifespan, which would correspond with membranes that are more fluid than those of whales, with a slow metabolism and a much longer lifespan.
This shows a little illustration of the basic structure of a cholesterol molecule.
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