CambExp10 - Precambrian Life and the Cambrian Explosion...

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1 Precambrian Life and the Cambrian Explosion Geologic Timescale (and dates to know) Oldest minerals Oldest rocks Oldest life First hard parts “Cambrian Explosion” Paleozoic Mesozoic Cenozoic K/T Extinction P/T Extinction Present
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2 What is life? • Self-reproducing - able to perpetuate information • Mutating - to allow for variation and therefore evolution • Metabolizing - to obtain and utilize energy Prerequisites for life • Liquid water - as a universal solvent • Raw materials - elements and compounds • Energy - to combine materials - chemical or light or heat
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3 Where did life originate? Where did life originate? • “Small, warm pond” - Chuck D. (in a letter to B. Hooker) • Hydrothermal vents • Near volcanoes • Clay Beds • Tidal Pools • Ocean Foam • Outer space!
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4 Intergalactic Organic Molecules Early Atmosphere • CH 4 (?), NH 4 (?), H 2 0, N 2 , H 2 , H 2 S, CO 2 O 2 (?) – Could have come from interstellar space • Lots of energy around – Lighting – Volcanoes and Vents – UV light - no ozone!
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5 Miller-Urey Experiment From compound to polymers • Polymers are long molecules, like the ones we associate with life now • Precipitation on clays, salts, or ice may have concentrated the early, simple molecules to allow them to make polymers
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6 The RNA World • RNA was probably one of the first self- replicating molecules – It carries information AND it can act as an enzyme for reactions • RNA probably led to DNA, because the latter is more stable
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This note was uploaded on 03/11/2010 for the course GE CLST 70B taught by Professor Morris,m.r./friscia,a.r./moldwin,m.b./vanvalkenburgh,b during the Winter '10 term at UCLA.

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CambExp10 - Precambrian Life and the Cambrian Explosion...

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