What function does the mitochondria have? What does it do?

The mitochondria, in short and simple terms, is like the "powerhouse" of the cell. It provides the cell energy to carry out it's proper functions. Mitochondria produce the energy necessary for the cell to be able function and survive. Mitochondria break down glucose into an energy molecule which is called adenosine triphosphate (ATP for short) through a series of chemical reactions. ATP is used to fuel various other cellular processes.