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The origins of Life. Origin of the Solar System. Earth is estimated to be ~4.6 bill. yr old Evidence: Radiometric dating of rocks & meteors Nebula Hypothesis: Nebula: cloud of gas & dust in space Gravity pulled much material together (forming the Sun)

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The origins of Life


Origin of the Solar System

  • Earth is estimated to be ~4.6 bill. yr old

    • Evidence: Radiometric dating of rocks & meteors

  • Nebula Hypothesis:

    • Nebula: cloud of gas & dust in space

    • Gravity pulled much material together (forming the Sun)

    • Planets formed from remaining materials


Ancient Earth

What was it like?

  • Atmosphere contents:

    • Ammonia, H2O vapor, Methane (CH4), CO2

  • Climate:

    • Extreme heat due to meteor impacts & volcanic activity

  • Eventually Cooling: Water vapor condensed (oceans formed)

Click on picture to play video clip


Organic Molecules

1. Miller - Urey Experiment

  • Hypothesis: Energy from lightning created organic materials from inorganic ingredients

  • Experimental Set-Up:

    • Ammonia, H2O vapor, Methane, CO gases added

    • Electricity added (simulate lightning)

  • Result: Amino Acids & later nucleotides were created


2 meteorite hypothesis
2. Meteorite Hypothesis

  • Hypothesis: Amino acids may have arrived on Earth through meteorite or asteroid impacts.

    • Fun Fact! 90 amino acids were found from this meteorite, only 19 of them can be found on Earth.

Murchison Meteorite


Early Cell Formation

  • Lipid membrane hypothesis

    • Liposomes

      • Spheres of lipids

      • Can form around

        organic molecules

      • Hypothesis: 1st cell membranes??????


Early Genetic Material

  • A hypothesis proposes that RNA was the first genetic material.

  • Ribozymes are RNA molecules that catalyze their own replication.

  • DNA needs enzymes to replicate itself.

  • Because of this, scientists think that DNA evolved from RNA


Eukaryotic Cell Formation

  • Endosymbiosis is a relationship in which one organism lives within the body of another.

  • Mitochondria and chloroplasts may have developed through endosymbiosis.


Multicellular Life & Biodiversity

  • Evolution of sexual reproduction led to increased diversity/variation.

  • Sexual reproduction may have led to multicellular life.


ReviewThese are questions that I would ask you on the test, so you should do your best at answering them accurately and completely.

  • What is a nebula?

  • What does the nebula hypothesis try to explain?

  • What materials/ingredients did Miller & Urey use in their experiment? Why these and not other ingredients?

  • Why was Miller and Urey’s experiment of great importance?

  • How did eukaryotic cells form?

  • How would sexual reproduction lead to diversity and multicellular life?


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