Biology / Unit 8 Bio 1821 short lesson, about 20 seconds
Endosymbiosis, Revisited as Genome Fusion
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The idea
Endosymbiotic theory, per Unit 2's Bio 0274, describes mitochondria and chloroplasts' origin as extreme horizontal gene transfer: a prokaryote engulfed and retained by another, fusing genomes.
In practice
Mitochondrial DNA, inherited separately from nuclear DNA and passed maternally, traces to a once free-living bacterium's genome.
Where people slip
Endosymbiosis is widely accepted for mitochondria and chloroplasts — this entry extends no such status to the nucleus's origin.
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