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