Direct evidence :. Fossilised chains of bacteria-like cells found in Marble Bar W.A. Occur in rocks dated at 3500 M yr ago. HOW DID LIFE GET HERE?. Still being debated as possible these structures were produced by geological action NOT biological. First signs of life?.
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Nitrogen, carbon dioxide, methane, ammonia, sulphur dioxide and hydrogen sulphide
Extreme UV radiation:
Extreme weather conditions:
Extreme geological activity:
Provides medium for reactions to occur and
an essential solvent.
Usable energy source:
Needed for all life’s functions.
The chemicals that make up all life
1. Organic molecules produced on early Earth
Aleksandr Oparin and J.B.S. Haldane suggested that the organic molecules needed for life were produced under the conditions on early Earth. (1920’s)
In the 1950’s Stanley Miller and Harold Urey set up a MODEL of early Earth to test Oparin and Haldane’s hypothesis.
Lightning in storms
Gases, CH4, NH3, H2O, H2
Gases found in Early Earth atmosphere
Water vapour due to water cycle
Water in newly formed oceans
1 week later:
Organic molecules found in the water
Showed that organic matter can be produced from inorganic material.
1969 – meteorite found in Victoria contained amino acids
Confirms organic molecules can be formed outside Earth
Early Earth was constantly bombarded with meteorites due to developing Solar System
Supports the idea that organic molecules arrived from space.
2001 – NASA replicated in the laboratory conditions that exist in interstellar clouds in space
Water mixed with inorganic chemicals, NH3, CO, CO2, CH3OH
Freeze to absolute zero in a vacuum
Expose to shortwave UV radiation
Complex organic molecules