Cell Biology · 4 min read
Mitochondria Were Once Free-Living Bacteria
The ‘powerhouse of the cell’ has an origin story stranger than the meme.
Mitochondria carry their own small circular DNA, divide independently, and have double membranes—clues to an ancient past.
Lynn Margulis championed endosymbiotic theory in 1967: an ancestral cell engulfed a bacterium, and instead of digesting it, the two became partners.
Genetic evidence now traces mitochondria to the alphaproteobacteria, confirming one of biology’s great merger stories.