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Sun formed.
Our solar system was a swirling mass of gas and dust. Over time, most of this material was pulled together by gravity and formed the sun. Scientists believe that the plants formed through repeated collisions of the leftover space debris. -
Earth formed.
Earth grew larger as gravity pulled in more debris. The collisions between Earth and space debris also released a great deal of thermal energy. -
Organic molecules accumulate.
Scientists infer that organic molecules began to accumulate. -
First cellular life.
Archaea are thought to be similar to the types of cellular life that first populated Earth about 4 billion years ago. -
Prokaryotes begin to photosynthesize.
Unicellular prokaryotes called lynbgya grew in colonies and formed layered structures called stromatolites. -
Life becomes photosynthetic.
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Earth looks the same.
By this time, Earth probably appeared much as it does today. -
O2 levels reached today’s levels
O2 levels reached today’s levels. -
Eukaryotes are formed.
A type of small aerobic prokaryote was "eaten" by a larger anaerobic prokaryote. The smaller prokaryote began to live and reproduce inside of the larger prokaryote. This theory is called endosymbiosis. -
Ozone (O3) formed.
Ozone (O3) formed – protected organisms from harmful UV rays so they could exist on land -
Redi
- rotting meat kept away from flies wouldn’t produce more flies.
- maggots appeared only on meat exposed to flies.
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Spallanzani
- boiled broth in two flasks
- Spallanzani concluded that microorganims wouldn’t grow in broth when its container was heated and then sealed.
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Pasteur
- used a variation of Spallanzani’s design to support that microorganisms are carried in the air and DO NOT arise by spontaneous generation.
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Oparian and Haldane
- proposed this hypothesis: at high temperatures, gases might have formed simple organic compounds, such as amino acids. -When Earth cooled and water vapor condensed to form lakes and seas, these compounds would have collected in the water. -These compounds could have entered complex chemical reactions; these reactions ultimately would have resulted in the macromolecules essential to life.
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Cech
- won the Noble Peace Prize for his discovery of the catalytic properties of RNA.
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Urey and Miller
-tested Oparian’s hypothesis
-they were successful -
Fox
-did research on physical structures that may have led to the first cells -
Margulis
-proposed that early prokaryotes may have developed a mutual beneficial relationship
