Functions Of A Cell Membrane

1198 Words Mar 14th, 2015 5 Pages
The cell is a basic unit of life. All living organisms are made up of cells. Cells are vital to maintain life and to allow reproduction. Each cell is separated from its surrounding environment by a cell membrane and acts as a barrier. The cell membrane is a cell’s most essential organelle. Cell membranes are composed of four different types of molecules; phospholipids, cholesterol, proteins and carbohydrates. The main function of a cell membrane is to control which substances can move in and out of the cell. Different organisms have different cell membranes.
The phospholipids create the basic structure of a cell membrane. A phospholipid has two separate ends; a head and a tail end. The head of the phospholipid is known as hydrophilic, meaning it is attracted to water molecules. The tail ends are made up of two strings of hydrogen and carbons atoms and are known as fatty acid chains. These chains are hydrophobic, meaning they don’t like water. These phospholipids make up the lipid bilayer. The lipid bilayer contains an certain arrangement of the phospholipids. The head (hydrophilic) end, are always facing the outside so they can be near water. The tail (hydrophobic) ends of phospholipids are arranged in a way that can keep them away from water, usually facing inwards. The cell membrane allows substances to diffuse directly through this lipid bilayer through passive diffusion. Diffusion is needed for the survival of cells as its main function is to obtain important nutrients…
Open Document