Chapter 12 The Cell Cycle Overview: The Key Roles of Cell Division Rudolf Virchow ? said ?where a cell exists, there must have been a preexisting cell, just as the animal arises only from an animal and the plant only from a plant?. Summarized by saying: ?omnis cellula e cellula? ? means every cell comes from a cell. Cell division ? plays several important roles in the life of an organism: Unicellular organism ? i.e. amoeba ? cell divides and forms duplicate, complete organisms. Larger scale ? cell vision can produce progeny (descendents) Enables sexually reproducing organisms to develop form a single cell (zygote) Can function in renwal or repair ? replacing cells that die (i.e. bone marrow, skin)