Cell membrane or plasma membrane
A thin membrane covering cytoplasm of a cell is called plasma membrane.
Occurrence:- occur in all living cells.
Plasma Membrane Versus Cell Membrane:
plasma membrane and cell membrane are not the same. They are different from each other. Plasma membrane as the name indicate is the membrane that surrounds the plasma. In other words it is the membrane that surrounds the organelles. On the contrary, cell membrane is the membrane that surrounds the entire cell.
Composition and structure;-It is a double layered membrane composed of lipids, proteins and very less amount of carbohydrates. Fluid mosaic model shows that there is a lipid bi-layer in which proteins molecules are embedded. Carbohydrates are bound to proteins.
Functions;- 1)controlling exchange of materials between the cell and environment. 2) control ion flow. 3) give shape to cell.