The Origin and Early History of Life

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The Origin and EarlyHistory of Life

• Lecture 4

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Early History of Life
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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

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How Did Life Appear?

• Panspermia extraterrestrial
• Special divine
• Chemical evolution
• Simple molecules
• Complex molecules 1st first cell EVER

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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

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Energy Input

• Lightning
• Soil radioactivity
• Ultraviolet radiation
• Volcanic heat

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Evidence of Primitive Conditions
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MillerUrey Experiment (1953)
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Experimental Conditions

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

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MillerUrey Experiment (1953)
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1. Place the atmosphere over liquid H2O
2. Maintain mixture somewhat below 100 degrees
   Celcius
3. Bombard mixture with energy.electrical sparks.

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MillerUrey Experiment (1953)
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Results

1. W/in one week, 15 of carbon from the atmosphere
   was converted into new molecules.
2. These new molecules formed more complex molecules.

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Other Results

• Further experiments produced a soup containing
• Amino acids
• Nucleic acid bases
• In 1998, RNA could replicate itself.
• Nice Hypothesis..whats missing?
• Cell Membrane

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The Earliest Cells

1. Found in fossils 3.5 BYA
2. Single cells, very small
3. Lacked nucleus prokaryotic
4. Resembled bacteria

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Earliest Cells
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Yellowstone Hot Pots Extremely High Temps
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Yellowstone Old Faithful Geysur
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Two Types of Bacteria

• Archaebacteria
• Produce methane
• Can live in the absence of oxygen
• Probably the most primitive

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Two Types of Bacteria

• Eubacteria
• Most bacteria today
• Cyanobacteria
• Appeared 2.5 BYA
• Capture light energy photosynthesis
• Produced O2 -- oxygen in the atmosphere

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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. Fungi 5. Plants 6. Animals