Primordial Earth

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Primordial Earth

• Theories on the Origin of Life

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Early Earth and Evolution

• A THEORY of the origins of the universe

• Big Bang
• When?
• Approx. 13.5 Billion years ago expansion from
  singularity
• MASSIVE AMOUNTS OF ENERGY!
• Energy eventually converted to fundamental
  building blocks of matter.
• Evidence?
• Expanding universe
• Background radiation
• Abundance of Hydrogen

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After Big Bang.

• Stars!
• Need hydrogen gas? fusion
• Form heavier elements
• Really big stars go out with a bang ? supernova!
• Planets!
• Leftover mess from supernova start to accrete
  into larger objects. (NEWTONS LAW!)
• Typically these objects will orbit around a star
• SOLAR SYSTEMS!

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LIFE!!!!

• Spontaneous Generation.
• Theory (hypothesis actually) that life can
  randomly emerge from non-living thing
• Biogenesis
• Theory that life only comes from pre-existing
  life.
• Common Ancestor
• Theory that every living organism on the planet
  is a descendent of an original cell
• Question Where did first life come from???

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Oparin-Haldane Hypothesis

• All the elements were already present on Earth.
• Early atmosphere contained mostly ammonia NH3,
  hydrogen gas H2, water H2O, and methane CH4.
• High temperatures might cause gases to form
  simple organic compounds.

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Prebiotic Soup

• As Earth cooled simple organic compounds
  collected in the lakes and seas.
• Energy from lightning and UV radiation caused
  chemical reactions to build macromolecules.

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Key Experiments

• Francisco Redis Flies
• Where do maggots come from
• Bottom Line no spontaneous generation

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Key Experiments

• Spallanzani
• Bacteria in broth come from air? Or other
  microbes?
• Bottom Line no spontaneous generation

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Key Experiments

• Louis Pasteur
• Bacteria in broth come from air? Or other
  microbes?
• Key difference from spallanzani?
• Bottom Line no spontaneous generation

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1953 Miller- Urey

• Stanley Miller and Harold Urey set up an
  apparatus to simulate the proposed primordial
  Earth conditions.

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1953 Miller- Urey

• Stanley Miller and Harold Urey set up an
  apparatus to simulate the proposed primordial
  Earth conditions.
• Found organic compounds.

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Debatable points

• Atmosphere probably contained CO, CO2, and N2
• Presence of O2, and CO2 interfere with production
  of organic compounds.
• Organic compounds produced in undersea volcanoes.
• Organic compounds came from outer space.

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Pre-Cell Structures

• Organic molecules aggregate spontaneously.
• Microsphere Protein membrane structure
• Coacervates Droplets of lipids amino acids, and
  sugars.

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Microspheres
Coacervates
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First Cells Prokaryotic

• Environment Little or no oxygen
• ? Cells were anaerobic.
• Environment Organic food molecules
• ? Cells were heterotrophs.
• Oldest fossils look like prokaryotes.
• ? Cells were prokaryotes.

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Archaea

• Present day cells, thought to be similar to
  earliest cells.
• Unicellular organisms that thrive in harsh
  environmental conditions.
• Anaerobic metabolism.
• Inorganic energy sources.

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Endosymbiotic Theory

• Creating the first eukaryotes
• Large prokaryotes engulfed smaller prokaryotes.
• Mutually beneficial relationship small cells are
  protected and large cell gets energy.

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• Small aerobic cells evolved into
• Small photosynthetic cells evolve into
• Mitochondria and chloroplast have their own DNA.
• DNA is circular, like prokaryotes.
• Replicate independently of cell.
• http//www.youtube.com/watch?vdSjg_uYS_QYfeature
  related

mitochondria
chloroplast.
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Summary

1. Small organic molecules were synthesized.
2. Small organic molecules (monomers) joined to form
   polymers, like protein and nucleic acids.
3. Molecules could self-replicate.
4. Molecules were packaged into membrane structures-
   resembling the first prokaryotic cell.