Cell Biology

Cell is a chemical system that is able to maintain its structure and reproduce. Cells are the fundamental unit of life. The body of some organisms like bacteria, protozoans and some algae is made up of a single cell while the body of fungi, plants and animals are composed of many cells.  The human body is built of about one trillion cells. Nothing less than a cell is alive. Group of cells can be organized and function as multicellular organisms.  The life of a cell depends upon thousands of chemical reaction and interaction coordinated with a genetic instruction of cell and its environment. Cytologists recognize two basic types of cells. Organisms which do not possess a well-formed nucleus are prokaryotes such as the bacteria.  All others possess a well-defined nucleus, covered by a nuclear membrane. They are eukaryotes.