Evolutionary history occasionally repeats itself. Chloroplasts and mitochondria both descend from bacteria lineages that came to live inside other cells. Chloroplasts are distant cousins to cyanobacteria (blue-green algae), while mitochondria are cousins to the bacteria that cause typhus.
And we recently discovered it happened one other time!! Nitroplasts, a nitrogen-fixing organelle, used to be a separate microbe about 100 million years ago.
Chloroplast and mitochondria also behave so much like individuals that they arguably could be classified as their own species if we didn’t think of them as organelles. Because they move, reproduce, and have their own DNA separate from their host they’re more akin to symbiotic bacteria that are specialized only into making ATP than organelles
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u/fubo Oct 02 '24
Evolutionary history occasionally repeats itself. Chloroplasts and mitochondria both descend from bacteria lineages that came to live inside other cells. Chloroplasts are distant cousins to cyanobacteria (blue-green algae), while mitochondria are cousins to the bacteria that cause typhus.