It is what makes organisms live till today. Without cells in organisms, there would not be life. The human, animal, plants and other organism not mentioned all have different organs in them with different functions. The cells are the unit that keeps them alive. The continuity of live is based on the reproductions of cells. The cells do not just reproduce anyhow. It has a control system and it is this control system that keeps the cell reproducing the right way and reproducing the right amount so as not to invade organs or produce and cause serious problems in the organ. Once the cells starts to reproduce excessively and do not controls over it, then that results into tumor cells otherwise known as the cancer cells. .
Cells reproduce or divide just as it is needed. We must know that every cell does die. Every cells in the living organism as its own lifespan and depending on what type of cell it is and what type of function it helps perform, cells can last for day up to several months. The amounts of cells that die equate the amounts of cells that are reproduced in the organisms. Cells divide by two ways in the organism, mitosis and meiosis. Every plant and animal including humans both utilize the mitosis and meiosis cell division. The mitosis makes its own clone out of its self to replace the dying cell. Only prokaryotes or bacterial replicates itself this way. During the division or reproduction of cell, there are several stages that it goes through. Mitotic division goes through the interface and under the interface is the G1 stage, the S stage, the G2 stage and the M stage. The G1 and the G2, and the M stage (Diagram 1) are called the checkpoint stages. According to Campbell Biology textbook "a check point in the cell cycle is a control point where stop and go-ahead signals can regulate the cycle". These checkpoints determine whether the cells are good to go or not. Then there are the prophase, metaphase, anaphase, and the Telophase.