Discuss in detail the structure of the plasma membrane with a diagram.

(N/A) The detailed structure of the plasma membrane was studied only after the advent of the electron microscope.
First,the study of the plasma membrane of human $RBC$ was conducted.
The plasma membrane is composed of lipids that are arranged within the membrane with the polar head towards the outer sides and the hydrophobic tails towards the inner part.
This ensures that the nonpolar tail of saturated hydrocarbons is protected from the aqueous environment. The lipid component of the membrane mainly consists of phosphoglycerides.
Biochemical investigation clearly revealed that the cell membranes also possess protein and carbohydrate. The ratio of protein and lipid varies considerably in different cell types.
In human beings,the membrane of the erythrocyte has approximately $52\%$ protein and $40\%$ lipids.
Depending on the ease of extraction,membrane proteins can be classified as integral or peripheral. Peripheral proteins lie on the surface of the membrane,while the integral proteins are partially or totally buried in the membrane.
An improved model of the structure of the cell membrane was proposed by Singer and Nicolson $(1972)$,widely accepted as the fluid mosaic model. According to this,the quasi-fluid nature of lipid enables lateral movement of proteins within the overall bilayer. This ability to move within the membrane is measured as its fluidity.