1. Shape giving: Cell membrane gives specific shape to each cell. Animal cells only have a plasma membrane, but plant cells have a cell wall outside the plasma membrane. Because of this, the cell membrane plays a key role in giving the specific shape of the animal cell.
2. Protection of living parts: The plasma membrane always covers the living protoplasm of the cell and protects it from external heat, pressure and injury.
3. Food intake: It takes in solid food by the process of phagocytosis and liquid food by the process of pinocytosis.
4. Organelle formation: It helps in the formation of some essential organelles of the cell like mitochondria, chloroplasts, Golgibodies, nuclear membrane etc.
5. As a chemical fast: cell membrane contains numerous consumer molecules. These consumer molecules maintain contact with the external environment. The plasma membrane collects information from the external environment chemically with the help of antigens, neurotransmitters, hormones etc.
6. Chemical secretion: It secretes enzymes and antigens for cells.
7. Physiological functions: Plasma membrane participates in respiration and other physiological functions in living organisms.
8. Conduction of impulses: It transports nerve impulses from outside to inside and from one cell to another.
9. Transport: Amino acids, glucose, ions etc. enter the cell through the plasma membrane. On the other hand, the carbon dioxide, ammonia, uric acid etc. created in the cells go out.
10. Absorption barrier: It acts as a barrier between the extracellular and intracellular medium.
11. Molecular motility: It regulates the molecular motility of the cell.
12. Energy production: Bacterial cell membrane folds to form mesosomes. Mesosomes undergo maturation and produce energy.
13. Growth and Movement: It helps in cell bonding, growth and movement.
14. As Antigen: In some cases cell membrane acts as antigen.
15. Enzyme content: There are 30 types of enzymes in the cell membrane. The most important enzymes are transport ATPases enzymes. This enzyme transports a variety of ions.
16. Basis: Cell membrane acts as a base for various information.
17. Receptors: act as receptors for hormones, neurotransmitters, mediated endocytosis, insulin etc.
18. Synthesis: Cell membrane synthesizes different types of large molecules.