The outermost, extremely delicate elastic membranous covering of the cell that separate its contents from the external environment is called plasma membrane.
Functions of plasma membrane :
1. Shape : Plasma membrane provides a definite shape to semi-fluid contents of the cell.
2. Mechanical barrier : It functions as mechanical barrier that protects the internal contents of the cell,
3. Selectively permeable : Plasma membrane determines what substances are to be allowed entry or exit from the cell.
4. Endocytosis : It helps the cell to engulf food and other substances from its external environment by endocytosis.
5. Recognition : The recognition centres of plasma membrane help in tissue formation, distinction of foreign substances and defense against microbes.
6. Flow of information : Plasma membrane provides flow of information amongst different cells of the same organism.
7. Osmosis : Osmosis occurs due to presence of tiny water channels in the plasma membrane.
8. Cell continuity : At places plasma membrane of adjacent cellsbecome continuous to form plasmodesmata and cell junctions.
9. Specialization : Plasma membrane gets modified to perform different functions. E.g. : absorption in microvilli.
