Why Do Our Cells Divide?

Human Life Cycle

You grew from a zygote, or fertilized egg (the fusion of two cells: an ovum and a sperm) into an organism with trillions of specialized cells. Mitosis is the process that enabled you to grow and develop after that fateful meeting of egg and sperm became ‘you’. That is the human life cycle.

Cell Replacement

So cells must divide in order for an organism to grow and develop, but cell division is also required for tissue repair, maintenance, cell turnover and replacement.

Many tissues of your body are composed of cells that have a high turn-over rate. Think of your skin. The epidermis, or top layer, is composed of dead cells that are constantly being sloughed off and replaced from below by cells of the dermis (the living cells in the layer of skin below the epidermis). If cells of the dermis were not constantly dividing to replace dead cells, your skin would eventually wear out.