Cell is defined as the structural and functional unit of the living body. All the living things are composed of cells. A single cell is smallest unit that has all the characteristics of life.
The general characteristics of most of the cells under normal conditions are:
- Cell needs nutrition and oxygen.
- It produces its own energy necessary for its growth, activities, and repair.
- It eliminates carbon dioxide and other metabolic wastes.
- It maintains the medium, i.e. the environment for its survival.
- It shows immediate response to the entrance of invaders like bacteria or toxic substances into the body.
- It reproduces by division. There are some exceptions like neuron, which do not reproduce.