9.1 The Origins of Life on Earth

• Primary Abiogenesis: The formation of life from non-living matter.
• Organic molecules (with CHO) can combine to create LIFE!

  1. Carbohydrates
  2. Lipids
  3. Proteins
  4. Nucleic acids
• Urey-Miller Experiment: Created organic molecules from inorganic

  molecules. Simulated life on early

  Earth.
• Where Did Life Begin?


  • Started in deep sea hydrothermal vents
  • Chemoautotrophic
  • Likely similar to modern day

  extremophiles or archaebacteria in

  deep sea vents
• Stromatolites: Dome shaped accumulations of bacteria
• The oldest photosynthetic prokaryotes lived 3.5 billion years ago
• Likely evolved from chemoautotrophs (create their own food using chemicals, not light. As photosynthetic organisms became more common, more oxygen was released into the atmosphere
• More oxygen in the atmosphere caused mass extinction of obligate anaerobes. This led to adaptation & created aerobic organisms
• Endosymbiosis Theory: The theory that the mitochondria and chloroplasts evolved from symbiotic bacteria
• Unicellular organisms evolved into

  multicellular organisms over hundreds of millions of years
• Geologic Time Scale: A system of dating and naming rocks based on the relative ages of the rocks.
• Three eras marked by major fossil record changes:

  1. Paleozoic
  2. Mesozoic
  3. Cenozoic
• Plates shift on hot mantle
• More competition between organisms in one land mass
• Break up of Pangea allowed for convergent evolution
• Convergent Evolution: When species evolve to have similar traits due to similar environmental pressures
• Long periods of stability followed by mass extinctions is common in Earth’s history. Allows for adaptive radiation of organisms that survive
• Five mass extinctions in Earth’s history