Cell Division

Every sexually reproducing organism, including humans, starts as a fertilized egg, or zygote. After that, in a regulated manner, trillions of cell divisions take place to create a sophisticated multicellular human. Stated differently, every other cell in the body descended from that original single cell. Even after an organism reaches adulthood, tissue regeneration or repair still requires cell proliferation.

For instance, fresh skin and blood cells are created continuously. Cell division is a process used by all multicellular animals for tissue and cell growth, maintenance, and repair. Cell division is strictly controlled, and when regulation breaks occasionally, it can have fatal results. Cell division is the reproduction mechanism used by unicells.