@vetuste_ennemi
Re abiogenesis: Human Universe 3 (last night) mentions the eukaryotic cell and the hypothesis that it was created through the symbiotic merging of two simpler single cells. Second time I've come across this idea recently.
15:00 Wed 22nd Oct 2014
Prof. Cox managed to do that without mentioning mitochondria but I knew this was what the merger was alluding to. I forget whether I learned this at uni or in subsequent years.
Incidentally, chloroplasts are also self-replicating and are thought to be a captured symbiotic lifeform.
To my mind, the collision was between a cell which had the full set of enzymes for respiration (sugar + oxygen + ADP -> ATP + CO2 + H2O) but they were floating loose on the cytoplasm and thus inefficient. The other was a better packed - thus more efficient - set of similar enzymes. By replicating faster than the big cell could 'eat' them, the mitochondria could contiue to exist.
The big cell thrived from faster metabolism and would eventually inactivate/mutate the respiration genes it no longer needed.
Mitochondrial DNA may have advanced since the time of the merger.
An analogy would be a rolling chassis, powered by elastic bands, crashing into an engine factory, capturing an engine and morphing the bands into something else.