Prebiotic evolution
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Prebiotic Evolution. Chapter 18. Until about 300 years ago people believed in the idea of spontaneous generation –that life comes from non-living material. 1668 Francesco Redi proved that magots did not come from rotting meat. Could microorganisms arise spontaneously?

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Until about 300 years ago people believed in the idea of spontaneous generation –that life comes from non-living material.

1668 Francesco Redi proved that magots did not come from rotting meat.

Could microorganisms arise spontaneously?

1864 Lois Pasteur finally disproved this idea.


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How did life arise on Earth?

1. “panspermia” – life arrived here from outer space

  • Not a testable hypothesis

    2. Prebiotic evolution – life arose from non-living matter


For prebiotic evolution to take place conditions on the early earth must have been very different l.jpg
For prebiotic evolution to take place, conditions on the early Earth must have been very different

  • The atmosphere contained virtually no free oxygen

  • There was no life on Earth

  • Life had 300 million years to get its act together


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  • Polysaccharides form formaldehyde (CHcoacervates in solution.

    • Membrane-like boundary

    • Act like cells

    • Absorb molecules and release products

    • Form new spheres by budding


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First information carrying molecule formaldehyde (CH

  • Was probably RNA since it does not need enzymes or a primer

    • RNA can act as an enzyme


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The first cells formaldehyde (CH

  • Were heterotrophs feeding off organic molecules in the oceans

  • Used fermentation – pathway common to all cells.


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Cyanobacteria formaldehyde (CH


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