1. The origin of Life

2. Origin of the Solar System
Earth is estimated to be ~4.6byo
Radiometric dating of rocks & meteors
Nebula Hypothesis:
Nebula: cloud of gas & dust in space
Gravity pulled much material together (Sun formed)
Planets: remaining materials

3. Ancient Earth Atmosphere contents: Climate:
Ammonia, H2O vapor, Methane (CH4), CO2
Climate:
Extreme heat due to meteor impacts & volcanic activity
Eventually Cooling: Water vapor condensed (oceans formed)
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4. 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

5. Murchison Meteorite 2. Meteorite Hypothesis
Hypothesis: Amino acids arrived on earth by a meteorite.
Murchison Meteorite

6. Early Cell Formation Lipid membrane hypothesis Liposomes
Spheres of lipids
Can form around
organic molecules
Hypothesis: 1st cell membranes?

7. 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.

8. 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.

9. Multicellular Life & Biodiversity
Evolution of sexual reproduction led to increased diversity/variation.
Sexual reproduction may have led to multicellular life.

10. Review
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?