Define cell? Mention the function of cell membrane?

The cell comes from the Latin word Cella Meaning "small room". It's can be define as the 

• Basic structural, functional and biological unit of all known organisms.
• Replicate independently 
• Building blocks of life                          

It's typically microscopic and consist of cytoplasm enclosed within a membrane which contains many biomolecules such as protein and nucleic acid.

Function of the cell membrane: 

1.  Maintains the physical integrity of the cell
2. Forms a barrier between the inside of the cell and the environment outside the cell
3.  Physically separates the intracellular components from the extracellular environment
4. Cell membrane also helps to hold the cytoskeleton
5.  Protects the cell from some harmful chemicals in its external environment
6. Protects the cell from loss of useful biological macromolecules
7. Selective Permeability
8. Active Transport
9. Markers & Signaling  (for communication with other cells & the external environment)
10.  Metabolic Activities
11. Bulk Transport: Exocytosis and Endocytosis



Ref: http://www.ivyroses.com/Biology/Cells/Cell-Membrane-Function.php