Transcript Origin of Life

• 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
• Atmosphere contents:
– 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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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
2. Meteorite Hypothesis
Hypothesis: Amino acids arrived on earth by a meteorite.
• Lipid membrane hypothesis
• Liposomes
– Spheres of lipids
– Can form around
organic molecules
– Hypothesis: 1st cell
membranes?
• 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.
• Endosymbiosis is a relationship in which
one organism lives within the body of
another.
• Mitochondria and chloroplasts may have
developed through endosymbiosis.
• Evolution of sexual reproduction led to
increased diversity/variation.
• Sexual reproduction may have led to
multicellular life.
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?