An organelle within cells that is responsible for the production of adenosine triphosphate (ATP), which is used as energy. It is also called a powerhouse of the cells. Mitochondria also perform a significant role in causing death (apoptosis) in cells.
That may sound odd, but it is important for growth and development processes. Cells sometimes don’t die when they should, and they start growing uncontrollably. This is how a tumor begins to grow, so you shouldn’t be surprised that mitochondria play an important role in cancer and is seen as an anti-cancer drug target.