Cell membrane: Uses and functions:
Cell membrane or plasma membrane or cytoplasmic membrane is the boundary that separates the cell interior and outside environment. This membrane or barrier is composed of proteins, phopholipids, cholesterol and carbohydrates. This membrane serves several purposes:
- selective barrier: the cell membrane acts as selective barrier for entry and exit of molecules in and out of cell. The lipid bilayer is selectively permeable, thus allowing entry of preferred molecules (such as nutrients) and exit of others molecules (such as non-preferred or useful molecules)
- shape: it provides shape to the cell (esp. if cell wall is absent). It may serve as base of attachment for the cytoskeleton, which will enable it to provide shape to the cell.
- barrier: it acts as a barrier between the cell interior and the outside environment.
- potential difference: a potential difference maintained across the membrane allows the diffusion of material in and out of cells.
- Flexibility: the membrane also renders flexibility to the cells.
Hope this helps.