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The Origin and Early History of Life

The Origin and Early History of Life. Lecture #4. Early History of Life. Time Frame. 10-20 billion years ago (BYA) – big bang 4.6 BYA – earth formed 3.5 BYA – life appeared (prokaryotes-bacteria) 2.5 BYA – oxygen-producing bacteria (cyanobacteria) 1.7 BYA – oxygen-breathing organisms

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The Origin and Early History of Life

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  1. The Origin and EarlyHistory of Life Lecture #4

  2. Early History of Life

  3. Time Frame • 10-20 billion years ago (BYA) – big bang • 4.6 BYA – earth formed • 3.5 BYA – life appeared (prokaryotes-bacteria) • 2.5 BYA – oxygen-producing bacteria (cyanobacteria) • 1.7 BYA – oxygen-breathing organisms • 1.5 BYA – eukaryotes (cells with nucleus) • 0.6 BYA -- multicellular

  4. How Did Life Appear? • Panspermia – extraterrestrial • Special – divine • Chemical evolution – Simple molecules Complex molecules 1st first cell EVER

  5. So….where did life come from? • Of all three ideas, only one is testable…..chemical evolution • Hypothesis • Life originated from (3.5 BYA) • Atmospheric gases • H2O • Energy input

  6. Energy Input • Lightning • Soil radioactivity • Ultraviolet radiation • Volcanic heat

  7. Evidence of Primitive Conditions

  8. Miller–Urey Experiment (1953)

  9. Experimental Conditions • Primitive atmosphere • N2 – nitrogen • NH3 – ammonia • CO2 – carbon dioxide • CO – carbon monoxide • H2 – hydrogen • CH4 – methane • Exclude O2 – no oxygen

  10. Miller–Urey Experiment (1953)

  11. Place the atmosphere over liquid H2O Maintain mixture somewhat below 100 degrees Celcius Bombard mixture with energy….electrical sparks.

  12. Miller–Urey Experiment (1953)

  13. Results • W/in one week, 15% of carbon from the atmosphere was converted into new molecules. • These new molecules formed more complex molecules.

  14. Other Results • Further experiments produced a “soup” containing: • Amino acids • Nucleic acid bases • In 1998, RNA could replicate itself. Nice Hypothesis…..what’s missing? Cell Membrane

  15. The Earliest Cells • Found in fossils 3.5 BYA • Single cells, very small • Lacked nucleus – prokaryotic • Resembled bacteria

  16. Earliest Cells

  17. Yellowstone Hot Pots Extremely High Temps

  18. Yellowstone Old Faithful Geysur

  19. Two Types of Bacteria • Archaebacteria • Produce methane • Can live in the absence of oxygen • Probably the most primitive

  20. Two Types of Bacteria • Eubacteria • Most bacteria today • Cyanobacteria • Appeared 2.5 BYA • Capture light energy – photosynthesis • Produced O2 -- oxygen in the atmosphere

  21. Classification of allLiving Things All living things can be classified into kingdoms. 1. Archaea – most primitive bacteria 2. Monera – modern bacteria 3. Protista – single cell eukaryotes and algae 4. Fungi5. Plants 6. Animals

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