geo 110 notes

Geo 110 notes - The Origin of Life Protostar and accretion disc H H=He liberates vast amounts of energy Enough energy to ignite star Have not

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The Origin of Life Protostar and accretion disc H+H=He liberates vast amounts of energy Enough energy to ignite star Have not viewed entire process, just stars in different stages of process Nebula=cloud-hotter in the middle, higher vaporization temps exist near the center (Fe) Earth’s iron core-most dense material pulled toward material Greatest impact- object size of mars-tilted earth’s axis of rotation- remnant of object that collided became the moon-moon was closer- continuously moving away Moon too small to hold atmosphere Meteors still collide w/earth/moon but with mush less frequency No collision record of meteors-erosion, continental drift Young earth chronology Oldest meteorites-4.56 Ga Oldest lunar rocks-4.44 Ga Oldest earth crustal mineral (Jack Hills zircon)-4.404 Ga (crystal) Fossil record begins at 3.5 Ga Life couldn’t have sustained before 3.9 Ga (meteors) Between 3.5-3.9 life began on earth First cellular life was bacterial Louis Pasteur 1822-1895 No spontaneous generation now Early Earth Atmosphere Derived from volcanism Mostly composed of H2O, CO2, N2 (like venus and mars) Possibly NH3, CH4 (ammonia, methane) in reduced amounts No O2 Therefore no ozone (O3), so no UV shield O2 arrived from photosynthesis O2 can be split by ultraviolet light, the single O atoms bond to another O2 and forms O3 (ozone) which absorbs ultraviolet light Gas reactions were driven by UV and lightning in atmosphere Reactions with NH3, CH4, CO2, H2O, N2 Formed new molecules HCN (cyanide) HCHO (formaldehyde) These gasses reacted with one another HCN+HCHO+H2O amino acid Entirely through inorganic process Reaction results accumulate in atmosphere and dissolve in oceans
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Ocean becomes “sludge” home for new products Dilute reaction vessel first life forms Stanley Miller 1953 Replicate conditions on early earth Amino acid containing brown sludge appeared within the first 24 hours 17 of 24 essential amino acids have been formed in experiment Have never made cell or “life”
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This note was uploaded on 03/27/2008 for the course GEO 310 taught by Professor Byers during the Spring '07 term at Wisconsin.

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Geo 110 notes - The Origin of Life Protostar and accretion disc H H=He liberates vast amounts of energy Enough energy to ignite star Have not

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