bio

Mitochondrion

The bean-shaped organelle in your cells where oxygen is used to burn food into energy. It carries its own loop of DNA, divides on its own schedule, and is wrapped in a double membrane — the lingering trace of a once-free-living bacterium that moved into a host cell about two billion years ago and stayed for good. The mitochondrion is living proof that one organism can become a permanent part of another and hand it a wholly new power.