Earth

1
Earths Early History
2
Mystery of Lifes Origins

• Using radiometric dating, scientists believe the
  Earth to be between 4.2 and 4.6 Billion Years
  Old.
• Earths early atmosphere contained little or no
  oxygen.
• Made up of mostly CO2, water vapor, and nitrogen

3
How did Life Begin?

• 3 ideas of how life may have gotten on Earth
• Divine Creation a higher being put us here on
  Earth
• Extraterrestrial Origin life may have come to
  Earth via an asteroid or meteorite.
• Spontaneous Origin process through which life
  is thought to have developed when molecules of
  non-living matter reacted chemically during the
  1st billion years.

4
Spontaneous Origin

• 1920s A.I. Oparin Primordial Soup Model
• Oceans were a big soup bowl with large amounts of
  organic molecules
• Chemical reactions spontaneously occurred in soup
  with energy from lightning/volcanoes
• Proposed that Earths early atmosphere lacked
  oxygen, yet had plenty of nitrogen, hydrogen,
  water vapor (earth was hot), methane and ammonia.

5
Stanley Miller

• 1953, tested Oparins hypothesis
• Placed gases in apparatus, zapped it, and found
  some basic chemicals could have formed
  spontaneously
• 2 problems
• Too slow
• Not sure methane and ammonia was available, and
  if it was, UV would destroy it

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7
Louis Lerman

• 1986 Bubble Model
• Chemical reactions took place in the bubbles of
  the ocean
• Reactions would take place faster in bubbles
• Inside bubbles, methane and ammonia protected
  from UV rays
• Leading hypothesis accepted to date

8
Origins of Eukaryotic Cells

• Endosymbiotic Theory proposes that a symbiotic
  relationship evolved over time, between primitive
  eukaryotic cells and the prokaryotic cells within
  them.
• Ex. Mitochondria and Chloroplasts are thought to
  have been ancient prokaryotes
• Both have their own DNA, ribosomes and both
  reproduce by binary fission like bacteria cells

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