The plasma membrane consists of 40 percent of lipid molecules and 60 percent of proteins. It plays a very important role in living organisms, in which one of its main functions is to act as a barrier between the internal and the external environment of each cell. Not only that, but it also controls the chemical reactions of a cell. In 1935, Davson and Danielli suggested that 40 percent of the lipid molecules are arranged in a ‘lipid bilayer’. …showed first 75 words of 843 total…

…showed last 75 words of 843 total…reticulum. Mitochondria also pocess a double membrane structure. In this organelle, the outer membrane plays an important protective, selective transport role. The inner membrane is enfolded into shelf like projections called cristae (singular: Crista). This gives a large surface area for the enzymes associated with the synthesis of ATP to work on. Overall, the plasma membrane plays a fundamental role in our cells, and without it our biological system wouldn’t be able to operate.