Explain in brief about the Cell Membrane

All cells, whether prokaryotic or eukaryotic, are bound by a limiting membrane called the cell membrane or the plasma membrane. The cell membrane gives shape and mechanical strength to the cell and protects it from the environment. The cell membrane is composed of lipids and proteins, and in many cases about 2-5% carbohydrates are also present. These carbohydrates are linked to the proteins or lipids. In plants, the cell membrane is covered by a rigid cell wall whose major component is cellulose. In fungi, the cell wall is made of chitin. Among the various models proposed for the plasma membrane, the most satisfactory model that is generally accepted is the fluid mosaic model of S.J. Singer and G.L.  Nicolson (1972). This model satisfactorily accounts for several of the observed properties of the plasma membrane.