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Chemical Evolution of Life

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Estimated time: 3 minutes
Maharashtra State Board: Class 12

Key Points: Chemical Evolution of Life

  • Chemical Evolution - Life originated by chemical reactions over a long period; proposed by Oparin (1924) and Haldane (1929).
  • Primitive Atmosphere - Earth formed ~4.6 bya from Nebula; atmosphere was reducing type (no free oxygen), rich in H₂, C, N, S.
  • Simple Molecules - H₂ reacted with other elements forming CH₄, NH₃, H₂O, H₂S; energy from UV rays and lightning formed amino acids, sugars, fatty acids, etc.
  • Primitive Broth - Simple organic molecules collected in water bodies forming "hot dilute soup" (Haldane); stable due to the absence of oxygen.
  • Complex Molecules & Nucleic Acids - Polymerisation formed proteins, fats; nucleotides joined to form RNA/DNA with self-replicating ability.
  • First Cell - Protobionts (coacervates by Oparin; microspheres by Fox) formed from organic molecules; developed into the first cell — anaerobic and heterotrophic.
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