THE ORIGIN OF LIFE
 The Evolutionary History of
     Biological Diversity
Chemical Evolution


Most biologists favored the hypothesis that life on
Earth developed from living materials that became...
Biogenesis Paradox
Spontaneous Generation
  Life emerging from inanimate materials

  Louis Pasteur

Biogenesis
  “Life-fr...
Four Stage Hypothesis
1) Abiotic synthesis of small organic molecules; amino
acids, nucleotides
2) Joining of these molecu...
Pasteur and
  Biogenesis of
 Microorganisms

1) Sterilized Beef Broth,
   after few days broth
  became spoiled with
     ...
Abiotic synthesis

Oparin & Heldane independently postulated that early
environments favored abiotic synthesis
  Oxygen at...
Miller-Urey
          #2    Experiment
               Atmosphere = H2O, H2,
               CH4, and NH3

               #1...
Another Hypothesis

It is also plausible that some organic compounds
reached the Earth from space. Scientists showed how
A...
Laboratory Simulations


Link monomers without the help of enzymes
  Polymerization by dripping on hot sand, clay, or rock...
RNA

RNA self-replication
  Ribozymes - RNA catalysts

  RNA self-replicated when added to organic monomers

  Autocatalyt...
Natural Selection

Single strand = variety of 3D shapes, giving it Genotype
and a Phenotype
Certain base sequences replica...
Protobionts
Aggregates of abiotically produced molecules
No precise reproduction
Can maintain an internal chemical environ...
Natural Selection &
         Protobionts

The most successful Protobionts would grow and split
Differential reproductive su...
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The Origin Of Life Key

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The Origin Of Life Key

  1. 1. THE ORIGIN OF LIFE The Evolutionary History of Biological Diversity
  2. 2. Chemical Evolution Most biologists favored the hypothesis that life on Earth developed from living materials that became ordered in to molecular aggregates that were eventually capable of self-replication and metabolism
  3. 3. Biogenesis Paradox Spontaneous Generation Life emerging from inanimate materials Louis Pasteur Biogenesis “Life-from-Life” Reproduction of previous life Early Earth Conditions were very different; oxygen, lightning, volcanic activity, sunlight
  4. 4. Four Stage Hypothesis 1) Abiotic synthesis of small organic molecules; amino acids, nucleotides 2) Joining of these molecules into polymers; proteins, nucleic acids 3) Origin of self-replicating molecules that made inheritance possible 4) Packaging into Protobionts--droplets with membranes and an inner chemical composition different than its surrounding
  5. 5. Pasteur and Biogenesis of Microorganisms 1) Sterilized Beef Broth, after few days broth became spoiled with microorganisms 2) Sealed sterile broth remained sterile for months 3a) Swan-neck flasks traps dust and microorganisms, remained sterile 3b) Broken swan-neck gave access to microorganisms; broth spoiled
  6. 6. Abiotic synthesis Oparin & Heldane independently postulated that early environments favored abiotic synthesis Oxygen attacks chemical bonds, extracting electrons Electron adding atmosphere from volcanic vapors enhanced the joining of simple molecules Energy was derived from intense UV radiation and lightning
  7. 7. Miller-Urey #2 Experiment Atmosphere = H2O, H2, CH4, and NH3 #1) Warm water simulated primeval sea #2) Sparks were #3 discharged to mimic lightning #3) Condenser cooled water and dissolved contents went back to the miniature sea After one week, the solution turned from clear to musky brown, #1 analysis showed variety of organic molecules, including amino acids and proteins
  8. 8. Another Hypothesis It is also plausible that some organic compounds reached the Earth from space. Scientists showed how Adenine could form by the reactions of cyanide in the clouds of stars. This would explain why some meteorites carried organic molecules
  9. 9. Laboratory Simulations Link monomers without the help of enzymes Polymerization by dripping on hot sand, clay, or rock Water splashing on fresh lava
  10. 10. RNA RNA self-replication Ribozymes - RNA catalysts RNA self-replicated when added to organic monomers Autocatalytic
  11. 11. Natural Selection Single strand = variety of 3D shapes, giving it Genotype and a Phenotype Certain base sequences replicate faster and more accurate Competition
  12. 12. Protobionts Aggregates of abiotically produced molecules No precise reproduction Can maintain an internal chemical environment different than the surrounding; metabolism and excitability Discharge voltage across surface in a nerve-like fashion Split and produces smaller replicas
  13. 13. Natural Selection & Protobionts The most successful Protobionts would grow and split Differential reproductive success of varied individuals Darwinism

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