garden/the-great-oxygenation.md

1,000 B

The Great Oxygenation

  • The diverity of [bacteria] exploded during the [Archaean], leading to the evolution of [Cyanobacteria]
    • This does not mean that Spirulina existed during the [Archaean]: it is a modern organism
  • There was almost no O₂ in the atmosphere before the [Archaean]-[Proterozoic] break
    • No O₂ means no formation of peroxides
    • Peroxides are dangerous to many cells as they rob electrons from proteins, fatally altering them
  • Cells had to develop anti-oxidation defenses, including catalase
  • Cells had two ways to adapt to O₂
    1. Become a strict anaerobe, and avoid oxygen-containing habitats
    2. Tolerate O₂
      • O₂ toleration can easily lead to aerobic metabolism