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Lecture #12 Date _______

Lecture #12 Date _______. Chapter 25 ~ Early Earth and The Origin of Life. You Must Knows. The age of the Earth and when prokaryotic and eukaryotic life emerged. Characteristics of the early planet and its atmosphere.

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Lecture #12 Date _______

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  1. Lecture #12 Date _______ • Chapter 25 ~ Early Earth and The Origin of Life

  2. You Must Knows • The age of the Earth and when prokaryotic and eukaryotic life emerged. • Characteristics of the early planet and its atmosphere. • How Miller and Urey tested the Oparin-Haldane hypothesis and what they learned.

  3. You Must Knows • Methods used to date fossils and rocks. • Evidence for endosymbiosis. • How continental drift can explain the current distribution of species.

  4. Early history of life • Solar system~ 12 billion years ago (bya) • Earth~ 4.5 bya • Life~ 3.5 to 4.0 bya • Prokaryotes~ 3.5 to 2.0 bya stromatolites • Oxygen accumulation~ 2.7 bya photosynthetic cyanobacteria • Eukaryotic life~ 2.1 bya • Muticelluar eukaryotes~ 1.2 bya • Animal diversity~ 543 mya • Land colonization~ 500 mya

  5. The Origin of Life • Spontaneous generation vs. biogenesis (Pasteur) • The 4-stage Origin of life Hypothesis: • 1- Abiotic synthesis of organic monomers • 2- Polymer formation • 3- Origin of Self-replicating molecules • 4- Molecule packaging (“protobionts”)

  6. Organic monomers/polymer synthesis • Oparin (Rus.)/Haldane (G.B.) hypothesis (primitive earth): volcanic vapors (reducing atmosphere) with lightning & UV radiation enhances complex molecule formation (no O2) • Miller/Urey experiment: • water, hydrogen, methane, ammonia • all 20 amino acids, nitrogen bases, & ATP formed • Fox proteinoid formation (abiotic polypeptides) from organic monomers dripped on hot sand, clay or rock • Oparin (coacervates) protobionts (aggregate macromolecules; abiotic) surrounded by a shell of H2O molecules coated by a protein membrane

  7. Abiotic genetic replication • First genetic material • Abiotic production of ribonucleotides • Ribozymes (RNA catalysts) • RNA “cooperation” • Formation of short polypeptides (replication enzyme?) • RNA~ DNA template?

  8. The Major Lineages of Life

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