The science that deals with the structure and function of cell is known as Cell Biology or Cytology (Greek.Kytos= container or cell; logos= to discourse). This branch of biology has its unique dimensions as it involves the study of cells from morphological, biochemical, cytochemical, physiological, genetical and developmental point of views. It encompasses both the great diversity of single celled organisms like bacteria and protozoa, as well as the many specialized cells in multicellular organism.