Transcript Origin of Life - Cloudfront.net

Origin of Life
Origin of the Solar System
• Earth is estimated
to be ~4.6byo
– Radiometric dating
of rocks & meteors
• Nebula: cloud of
gas & dust in space
• Nebula Hypothesis:
– Gravity pulled much
material together
(Sun formed)
– Planets: remaining
materials
Ancient Earth
• Atmosphere contents:
– Ammonia, H2O vapor,
Methane, H2,
• Climate:
– Extreme heat due to
meteor impacts &
volcanic activity
• Eventually Cooling:
Water vapor
condensed (oceans
formed)
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Where did organic molecules
come from?
• 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
Murchison Meteorite
Cell Formation?
• Lipid membrane hypothesis
• Liposomes
– Spheres of lipids
– Can form around
organic molecules
– Hypothesis: 1st cell
membranes?
RNA as 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.
What about eukaryotic cells?
How did they form?
Eukaryotic cells may have evolved
through endosymbiosis.
• Endosymbiosis is a relationship in which one
organism lives within the body of another.
• Mitochondria and chloroplasts may have
developed through endosymbiosis.