A cell is the smallest, structural and functional unit of living organism capable of caring out life’s functions.

Some organisms like Amoeba have only one cell and they are said to be unicellular organisms .Others are made up of many cells (multicellular organisms). So all living organisms are made up of cells .Cell were first discovered by Robert Hooke using a light microscope .He saw cells as small bosses .

A generalized structure of an animal      a generalized structure of a plant cell as

Cell as seen under a light microscope            seen under an electron microscope

Cells are made up of different structure specialized for different functions. These structures are called organelles. An organelle is a structure within a cell bounded by a membrane and having a particular function in the cell. The world contents of the cell are called protoplasm (nucleus + cytoplasm).