history of life handout

history of life handout - 1 A brief history of Life on...

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Unformatted text preview: 1 A brief history of Life on Earth Dr. K. Stanger-Hall Earth ~ 4 billion years ago Earth today •Universe ~ 10-20 billion years old •Solar system ~ 4.5-5 billion years old •Earth ~ 4.5 billion years old Earth crust solidifies Bombardment from Outer Space ceases About 4-3.8 billion years ago: 2 Earth: Life evolves • Phospholipids (->membrane-enclosed spaces) • RNA molecules (self-replicate and enzymes for metabolism) About 3.8-3.5 bio years ago: Western Australia: The first fossil prokaryotes About 3.5 billion years ago: Bacteria build stromatolites 3.5 by old filamentous prokaryote from Western Australia? Stromatolite fossil from Michigan Athmospheric Conditions • Atmosphere of early earth: Hot! – carbon monoxide (CO), – carbon dioxide (CO2), – Nitrogen (N2), – water vapor (H2O) – NO FREE OXYGEN, or just trace amounts • Athmosphere of present day earth: Cooler – 78% nitrogen (N2) – 21% oxygen (O2) – 0.035% carbon dioxide (CO2) – traces of rarer gases (Helium, Neon) About 3.8-3.5 bio years ago versus today: 2 Earth: Life evolves • Phospholipids (->membrane-enclosed spaces) • RNA molecules (self-replicate and enzymes for metabolism) About 3.8-3.5 bio years ago: Western Australia: The first fossil prokaryotes About 3.5 billion years ago: Bacteria build stromatolites 3.5 by old filamentous prokaryote from Western Australia?...
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history of life handout - 1 A brief history of Life on...

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