Every living thing on this planet has some type of membrane. Membranes are thin structures, measuring 8 nm thick. They are the major barrier in the cell, separating the inside of the cell from the outside. It is the structure which allows cells to selectively interact with their environment. Membranes are highly organized and asymmetric having two faces with different topologies and different functions.
Membranes are also dynamic, constantly adapting to changing environmental conditions.
Structure of components Lipids Membranes are composed of phospholipids and proteins. There are also two fatty acid chains dangling from the other carbons of glycerol. The phosphate end of the molecule is hydrophilic and is attracted to water. The fatty acids are hydrophobic and are driven away from water. The first figure shows the structure of the lipid ethanol amine.