Cell membrane



The cell membrane (also called the plasma membrane) is the outer lining of a cell. This structure is a feature of cells that is universal. It encloses all living cells, both prokaryotic and eukaryotic. This membrane serves to separate and protect a cell from its surrounding environment and is made mostly from a double layer of proteins and lipids, fat-like molecules. They are only 7.5 to 10 nanometers thick. Embedded within this membrane are a variety of other molecules that act as channels and pumps, moving different molecules into and out of the cell. A form of plasma membrane is also found in prokaryotes, but in this organism it is usually referred to as the cell membrane.