Basic Cell Parts Involved in Mitosis

Why Must a Cell Divide?

What Does Mitosis Do?

Built-In Controls in Mitosis

Links

For Teachers

Why Must a Cell Divide?

We all know that most all cells are microscopic in size. But why is this? As we all grow, why don’t the cells just get bigger instead of getting more of them?

Cells are limited in size because the outside (the cell membrane) must transport the food and oxygen to the parts inside. As a cell gets bigger, the outside is unable to keep up with the inside, because the inside grows a faster rate than the outside.

This can be represented by what is called the surface to volume ratio, or S : V, or S/V. In a cell that is one unit in size, the surface area is 6 square units and the volume is 1 cubic unit. The ratio then is 6/1. As a cell gets larger, this ratio gets smaller, meaning the cell membrane cannot supply the inside with what it needs to survive.