Biology / Unit 2 Bio 0274 short lesson, about 20 seconds
Endosymbiosis
Captions available
The idea
Endosymbiotic theory holds that mitochondria and chloroplasts descend from free-living bacteria an ancestral host cell engulfed and kept rather than digested.
In practice
Margulis's 1967 argument cited the size, DNA, and ribosomes mitochondria and chloroplasts share with bacteria as evidence for that ancestry.
Where people slip
This entry teaches endosymbiosis as the field's well-supported account, not one option among equals.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Something wrong in this lesson? Flag it · Sources for Biology