1. Origin of Life
SC.912.L.15.8

2. Conditions on early Earth
*Reducing atmosphere
water vapor (H2O), CO2, N2, NOx, H2, NH3, CH4, H2S
lots of available H & its electron
no free oxygen
Energy source
lightning, UV radiation, volcanic
low O2 = organic molecules do not breakdown as quickly
* Are there alternative topics?
What’s missing from that atmosphere?

3. Origin of Organic Molecules
Abiotic synthesis
1920 Oparin & Haldane propose reducing atmosphere hypothesis
1953 Miller & Urey test hypothesis
formed organic compounds
amino acids
adenine
Oparin and haldane: energy from lightning and intense UV radiation (early oceans were a primitive soup
Urey and Miller: teted this hypothesis

4. What is science? Uncovered jars Covered jars Controlled Variables:
jars, type of meat,
Location, temperature,
time
In a controlled experiment, only one variable is tested at a time. Redi designed an experiment to determine what caused the sudden appearance of maggots. In his experiment, the manipulated variable was the presence or absence of the gauze covering. The results of this experiment helped disprove the hypothesis of spontaneous generation.
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5. Manipulated Variable: Gauze covering that keeps flies away from meat
Several days pass.
Responding Variable:
whether maggots appear
Maggots appear.
No maggots appear.
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6. Pasteur’s Test of Spontaneous Generation
Louis Pasteur conclusively disproved the hypothesis of spontaneous generation.
Pasteur showed that all living things come from other living things.
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7. Pasteur’ s Experiment Broth is free of microorganisms for a year.
Curved neck is removed.
Broth is teeming with microorganisms.
Pasteur’s experiment showed that boiled broth would remain free of microorganisms even if air was allowed in, as long as dust and other particles were kept out.
Broth is boiled
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8. 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.
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9. First Eukaryotes ~2 bya Development of internal membranes
create internal micro-environments
advantage: specialization = increase efficiency
natural selection!
nuclear envelope
endoplasmic reticulum (ER)
plasma
membrane
infolding of the plasma membrane
nucleus
Endosymbiotic theory
Stromatolite: layered rocks that form when certain prokaryotes bind this films of sediment together
DNA
cell wall
plasma
membrane
Prokaryotic
cell
Prokaryotic ancestor of eukaryotic cells
Eukaryotic
cell

10. Endosymbiosis Evolution of eukaryotes origin of chloroplasts
Eukaryotic
cell with
mitochondrion
Evolution of eukaryotes
origin of chloroplasts
engulfed photosynthetic bacteria, but did not digest them
mutually beneficial relationship
natural selection!
photosynthetic bacterium
chloroplast
mitochondrion
Endosymbiosis
Eukaryotic cell with
chloroplast & mitochondrion

11. Review Questions

12. Review Questions

13. Review Questions