RLO: Cell Division



The adult human body is composed of an amazing 75 trillion cells, all descended from a single cell produced during fertilisation. The fertilised cell divides repeatedly forming the tissues and organs of the developing baby. After birth this cell division continues as the individual grows, until physical maturity.

Even when growth and development are complete cell division is still important as most cells have a limited life span and must be replaced. Cells are also damaged by physical wear and tear, chemical changes or other factors, and these also need replacing.

Finally, if we are to reproduce we must produce the sex cells, the sperm and the ovum, which are created in the testes and ovaries.

There are two types of cell division: mitosis and meiosis.