The text describes the evolutionary developments through which prokaryotes gradually evolved increasingly efficient strategies for energy production – from the use of inorganic electron donors to photosynthesis and finally to endosymbiosis with aerobic bacteria – thereby laying the foundation for complex life forms. The emergence of eukaryotes traces back to an endosymbiosis involving photosynthesising cyanobacteria and archaeal ancestors such as the Lokiarchaea, with geological processes like the formation of continents and the provision of phosphorus playing a crucial role alongside biological symbiotic strategies—demonstrating the remarkable diversity and adaptability of life on Earth.
This episode describes the second part of the evolutionary history of how prokaryotes harnessed energy.
Stage 5: Increased efficiency of electron transport systems
Stage 6: Return flow of protons for ATP synthesis
Stage 7: Reduction of CO₂ to obtain carbon – reducing agents unavailable
Stage 8: New strategies for hydrogen (H₂) acquisition
– Use of deep-sea volcanoes, chemosynthesis
– Rock transformation
– Use of radioactive radiation
Stage 9: Use of UV light (beginning of photosynthesis)
– Green sulphur bacteria used hydrogen sulphide and developed a new reducing agent
– Cyanobacteria used water
Stage 10: Two coupled photosystems
Stage 11: Detoxification and utilisation of oxygen
Stage 12: Endosymbiosis – origin of mitochondria
Stage 13: Endosymbiosis – origin of chloroplasts and eukaryotes