Cell theory is a proposed and widely accepted view of how most life on Earth functions. According to the theory , all organisms are made of cells. The cell theory states: All organisms are composed of one or more cells. The cell is the basic unit of life in all living things. All cells are produced by the division of pre-existing cells. Learn about the scientific theory that living organisms are made of cells, the basic unit of structure and reproduction. Explore the history of cell discovery, from Robert Hooke's observation of cork pores to Anton van Leeuwenhoek's study of microorganisms.
