Origins of Life Ch' 142

1
Origins of Life (Ch. 14-2)

• Early hypothesis
• Spontaneous Generation (abiogenesis) living
  organisms can arise spontaneously in a few days
  or weeks from non-living matter

2
Francesco Redi

• Mid 1600s
• Proved spontaneous generation to be false
• Proved that maggots did not spontaneously appear
  on rotting meat, flies had to be present first

3
Louis Pasteur

• 1860
• Proved that presence of air alone could not
  produce microorganisms in broth
• Swan-neck flask allowed air to enter but not
  organisms

4
Modern hypothesis

• Miller-Urey Experiment (1953)
• Put gases (NH3, CH4, H2, and H2O vapor) thought
  to be present in earths early atmosphere into a
  closed environment
• Electric currents were added to simulate
  lightning
• Organic compounds like amino acids formed

5
First Cells

• First cell was a protocell
• Anaerobic
• Used organic molecules for food
• Eventually photosynthetic prokaryotes evolved and
  began to release oxygen
• Eukaryotic cells evolved from prokaryotic cells
  through endosymbiosis

6
Endosymbiotic Theory

• Symbiosis relationship between two organisms
• Ancient prokaryotes may have engulfed smaller
  prokaryotes which evolved into organelles
  mitochondria or chloroplasts
• Mitochondria and chloroplasts have their own DNA
  and ribosomes