1'3 Where does life come from

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1.3 Where does life come from?
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Spontaneous generation and biogenesis

• Spontaneous Generation - the idea that living
  things could come from not living things.
• Early experiments showed spontaneous Gen. Doesnt
  usually happen but didnt totally disprove it.
• 1800s Pasteur designed experiment that
  disproved spontaneous generation
• Replaced it with biogenesis - the theory that
  life comes only from other living things.

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Lifes origins

• If living things only come from living things
  where did the first living thing come from.
• 5 billion years ago solar system was whirling
  dust cloud.
• 4.6 BYA the earth was formed.
• 3.5 Billion year old fossils have been found.

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Oparins Hypothesis

• Suggests that earths early atmosphere was mostly
  ammonia, hydrogen, methane, and water vapor.
• Hypothesized that these gases could have combined
  to make the more complex compounds in living
  things.

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Testing Oparins Hypothesis

• Urey and Miller set up an experiment to test the
  hypothesis.
• The two americans found that the complex
  compounds could be produced.
• Spontaneous generation has been disproved but the
  origin of life is still debated.