Cells divide for reproduction, replacement of lost or dead cells and to promote growth. Cell division is necessary for survival. There are two methods to accomplish cell division, known as mitosis and meiosis.
All living organisms experience cell division as a part of survival. This includes plants, animals, bacteria and fungi. Reproduction is the oldest, and perhaps the simplest, reason cells divide. In reproductive fission, one cell typically grows larger than usual, duplicates its organelles and any internal structures, and then divides into two nearly identical cells. Bacteria, for instance, use binary fission for cell division to reproduce and multiply. Among microbes, this process, which is referred to as mitosis, is one of the most common means for reproduction. In multicellular organisms, such as plants and animals, cells undergo a special form of cell division known as meiosis.
Replacement of Dead or Lost Cells
Plant and animal cells also divide for reasons related to the needs of the organism. When a skin cell is damaged, for example, the cells near the site of the damage often divide as a way of replacing the lost tissue. Through a series of six phases, mitosis takes on the important task of replacing these dead or lost cells. This is the repairing mechanism for the tissues that need mending. Basically, an injury to tissue stimulates growth factors in an extracellular matrix (ECM). This ECM contains the necessary biological programming to perform the repairs. Kind of like a first aid kit, the ECM uses water, essential minerals and compounds to aid in the healing process. Once the ECM takes over, the cell typically stops dividing. However, sometimes over-exposure or genetics can cause this to get out of control, causing a mutation. A mutation in human bodies can be caused by external exposure to excess sunlight, pollution, cigarette smoke and other toxins. It can also be caused internally by errors that happen within the DNA-copying process, which is sometimes based on genetics.
Growth Through Cell Division
Cell division actually produces new cells for growth. Think of an athlete who breaks down muscle tissues and fibers through exercise. The tissues and cells repair and create new growth. Therefore, the muscles gain strength with new cells. This breakdown of tissue and replacement with new cells is part of a cell cycle. The longer someone lives and the larger his or her size is, the more cells he or she will have within his or her body. Certain cells are in constant growth mode, including skin cells. Because these skin cells are shed, they have to be replaced. As many as 50 million skin cells are shed daily, according to biologists. Other cells, including nerve and brain cells, do not require as much cell division. A built-in control system within the body keeps this cellular growth in check. It knows when to make new cells and when to stop producing them. Occasionally, there is a glitch in the cellular-division system. In the event that a cell continually divides and makes more than is needed, cancer cells can develop, leading to disease. The cell-division process has to keep a balance to remain healthy.