We would probably be in a lot of trouble if we didn't have mitosis! In fact, we probably wouldn't exist at all. From the time an egg is fertilized by a sperm, mitosis starts to happen. And in our daily lives, skin cells, stomach cells, hair cells, bone cells, and other tissue cells are undergoing mitosis!

Mitosis is the process by which cells divide. Without it, you could make no new cells. The cells in most of your body would wear out very quickly, greatly shortening your life.

No life would be possible without mitosis. Cell theory tells us that all living things are made of cells and that all cells come from other cells. How does one cell become two cells? By dividing. But the cell can’t divide into 2 living cells unless it copies its DNA, then divides the DNA evenly into the two halves that are about to become two cells. The division of the DNA into the “daughter cells” is mitosis.

A fertilized egg cell can only turn into the trillions of cells in a human by doing an awful lot of cell division. Even after we finish growing, we need cell division to replace the cells that we constantly lose from our skin, digestive tract, and other places. We also need new cells to repair tissues, fight disease, and make reproductive cells.

The main reason we age is that our cells don’t divide as much as they did when we were young, so aging gives you an idea about what happens when there is less mitosis.

Some types of cells in our bodies do very little mitosis after we’re born. Can you figure out which ones?

Cell biologists and geneticists are very interested in questions like these. You may want to consider a career in one of these fields.