From Parasite Eve Video Game

Mitochondria

Mitochondria are organelles found within the cells of all living things. Possessing DNA different from that in the cell's nucleus, mitochondria may be the remains of a seperate organism that the nucleus absorbed into the cell shortly after life on this planet began. Opposing theories state that mitochondria deliberately entered the cell as a nucleic parasite. mitochondria generate ATP, an important source of cell power.

Mitochondria Eve

Based on data taken from mitochondria DNA collected from people of various ethnic backgrounds, a hypothesis was formed tracing all mitochondria to a single source: a female human in ancient Africa, identified as "Mitochondria Eve."