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History of Life on Earth

History of Life on Earth. Theories and Ideas on How Life Began and What Has Happened Since. From Nothing to Everything?. The Big Bang: Earth’s Prehistory. The Big Bang: Earth’s Prehistory. The Big Bang Theory is the dominant scientific theory about the origin of the universe.

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History of Life on Earth

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  1. History of Life on Earth Theories and Ideas on How Life Began and What Has Happened Since

  2. From Nothing to Everything?

  3. The Big Bang: Earth’s Prehistory

  4. The Big Bang: Earth’s Prehistory • The Big Bang Theory is the dominant scientific theory about the origin of the universe. • Created the universe between 10 billion and 20 billion years ago • Cosmic explosion hurled matter in all directions

  5. The Prebiotic Earth: First Billion Years

  6. The Prebiotic Earth: First Billion Years • In order for life to exist on Earth, four requirements must have existed: • Presence of chemical building blocks • Source of energy • Little or no free oxygen • Time • Major elements found in living things: • C, H, O, N, P, S

  7. Oparin’s Hypothesis

  8. Oparin’s Hypothesis • 1930s - Alexander Oparin hypothesized that life began between 3.9 to 3.5 billion years ago. • Simple organic molecules containing carbon formed • Energy from the sun, lightning, and earth's heat triggered chemical reactions • Organized by chance into complex organic molecules • 1952 - Miller-Urey Experiment • Simulated conditions on Earth ~4 billion years ago • Experiment made some of the fundamental building blocks of life • This suggests that these can form naturally • Still flaws with the experiment though

  9. Iron-World Hypothesis

  10. Iron-World Hypothesis • Suggests that life began in deep-cracks in the Earth’s deep ocean floor • Lab experiments show production of simple organic compounds

  11. Evolution of Oxygen Contentof Earth’s Atmosphere

  12. The Origin of Life on Earth

  13. The Origin of Life on Earth • Life began in the sea as single-celled organisms • Life develops into more complex forms through gradual evolution • Early organisms had no hard parts to leave fossil

  14. Geological Time Scale

  15. Catastrophes? That’s Normal!

  16. Catastrophes? That’s Normal! • Life on Earth has been punctuated by catastrophes • Catastrophes cause ecosystems to collapse and species become extinct • Adaptive radiation occurs following mass extinction

  17. Endosymbiosis Theory

  18. Endosymbiosis Theory • Theory suggests that prokaryotes (simple cells) gave rise to the first eukaryotes (more complex cells) • Bigger prokaryotic cell engulfed smaller heterotrophic prokaryotic cell • Prokaryotic cell became dependent on host cell, which received more ATP production

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