Thriving In An Oxygen World

The Mighty Mitochondria

1600 MYA

Mitochondria reside, sometimes by the hundreds, inside each of our cells. They respire the oxygen that keeps alive the cells of animals, plants, fungi, and most protoctists.

Mitochondria look like the free-living symbiotic bacteria from which they came. They do their own thing: they have their own private DNA and they grow and divide on their own inside each cell. Fortunately for all oxygen-breathing organisms, mitochondria cannot abandon us, as they can no longer live outside of our cells.

Have you ever thought of yourself as akin to a mitochondrion, living without the protective cell of our Earth? What part do we play in this symbiotic planet?

Oxygen-energized protoctists wildly diversify life. Planktic (floating) and benthic (bottom-dwelling) beings thrive, thanks to their symbiotically acquired, air-breathing mitochondria. (Photography by David Caron, Woods Hole Oceanographic Institution)

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