Post on 05-Jan-2016
Origin of LifeOrigin of LifeSC.912.L.15.8
Conditions on early EarthConditions on early Earth• *Reducing atmosphere
o water vapor (H2O), CO2, N2, NOx, H2, NH3, CH4, H2S o lots of available H & its electrono no free oxygen
• Energy sourceo lightning, UV radiation,
volcaniclow O2 = organic molecules do not breakdown as quickly
low O2 = organic molecules do not breakdown as quickly
What’s missingfrom thatatmosphere?
* Are there alternative topics?
Origin of Organic MoleculesOrigin of Organic Molecules
• Abiotic synthesiso 1920
Oparin & Haldane propose reducing atmosphere hypothesis
o 1953Miller & Urey test hypothesis
• formed organic compoundso amino acidso adenine
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What is science?What is science?
Controlled Variables:jars, type of meat,Location, temperature,time
Covered jarsUncovered jars
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Manipulated Variable:Gauze covering that keeps flies away from meat
Responding Variable:whether maggots appear Maggots appear.
Severaldays pass.
No maggots appear.
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Pasteur’s Test of Spontaneous Generation
oLouis Pasteur conclusively disproved the hypothesis of spontaneous generation.oPasteur showed that all
living things come from other living things.
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Pasteur’ s ExperimentPasteur’ s Experiment
Broth is boiledBroth is freeof microorganismsfor a year.
Curved neck isremoved.
Broth is teeming with microorganisms.
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The Impact of Pasteur’s Work
Pasteur saved the French wine industry, which was troubled by unexplained souring of wine.
He began to uncover the nature of infectious diseases, showing that they were the result of microorganisms.
First EukaryotesFirst Eukaryotes• Development of internal membranes
– create internal micro-environments– advantage: specialization = increase efficiency
• natural selection!
infolding of theplasma membrane
DNA
cell wall
plasmamembrane
Prokaryoticcell
Prokaryotic ancestor of eukaryotic cells
Eukaryoticcell
endoplasmicreticulum (ER)
nuclear envelope
nucleus
plasma membrane
~2 bya
mitochondrion
chloroplast
Eukaryotic cell withchloroplast & mitochondrion
Endosymbiosis
photosyntheticbacterium
EndosymbiosisEndosymbiosis• Evolution of eukaryotes
o origin of chloroplasts o engulfed photosynthetic bacteria,
but did not digest themo mutually beneficial relationship
• natural selection!
Eukaryoticcell with mitochondrion
Review QuestionsReview Questions
Review QuestionsReview Questions
Review QuestionsReview Questions