π Node [[the great oxygenation]]
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 Oβ in the atmosphere before the
[[Archaean]]-[[Proterozoic]] break
- No Oβ 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 Oβ
- Become a strict anaerobe, and avoid oxygen-containing habitats
-
Tolerate Oβ
- Oβ toleration can easily lead to aerobic metabolism
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