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• 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
Origin of the Solar System
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
Ancient Earth
Organic Molecules
Hypothesis: Energy from lightning created organic materials from inorganic ingredientsExperimental Set-Up:
Ammonia, H2O vapor, Methane, CO gases addedElectricity added (simulate lightning)Result: Amino Acids & later nucleotides were created
1. Miller - Urey Experiment
2. Meteorite Hypothesis
Murchison Meteorite
• 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.
• Lipid membrane hypothesis– Liposomes
• Spheres of lipids• Can form around
organic molecules• Hypothesis: 1st cell
membranes??????
Early Cell Formation
• 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.
EARLY GENETIC MATERIAL
– Because of this, scientists think that DNA evolved from RNA
• Endosymbiosis is a relationship in which one organism lives within the body of another.
• Mitochondria and chloroplasts may have developed through endosymbiosis.
Eukaryotic Cell Formation
• Evolution of sexual reproduction led to increased diversity/variation.
• Sexual reproduction may have led to multicellular life.
Multicellular Life & Biodiversity
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?