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5 BYA (solar system formed)
Gas and dust come together to create the sun, and the remaining debris revolved around it. planets were formed by collisions of the debris -
Period: to
timeline
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4.6 BYA (earth begins to form)
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4 BYA (rocks)
oldest known rocks and crystals form. scientists are able to determine the approxiamte time of formation through radioactive decay -
4 BYA (archaea)
the first life on earth appears in the form of archaeabacteria -
3.5 BYA (cyanobacteria)
Lynbgya, a genus of cyanobacteria, first begins to grow in colonies called stromatolites -
3 BYA (development of plants)
some life forms begin to become photosynthetic -
2.2 BYA (earthlooks like it looks today)
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2 BYA (oxygen)
oxygen levels reach where they are today -
1.5 BYA (prokaryote)
a small, aerobic prokaryote was engulfed by and began to live and reproduce inside of a larger anaerobic prokaryote. this is called endosymbiosis -
1 BYA (ozone)
the ozone layer is formed, allowing orgamnisms to be protected against UV rays -
Spallanzani's experiments
Lazzaro Spallanzani conducted and experiment with broth to see how long it would take for microorganisms to form depending on whether the flask was sealed or not. he found that the broth became cloudy (filled with microorganisms) quickly when the flask was open but the broth remained clear for several days when the flask was sealed, proving that microorganisms are carried in the air -
Redi's experiments
in the 1650s, a scientist named Fransesco Redi conducted an experiment with meat to see if maggots would formed if the container was sealed. he found that no maggots formed on the meat that was sealed, proving that spontaneous generation does not exist -
microscope
in 1665, Robert Hook created the light microscope to look at nature -
Pasteur's experiments
in the mid-1800s, Louis Pasteur conducted an experiment similar to Spallanzani's, except instead of sealing the flask he made a curved neckl flask and left it open and compared it to a regular open flask. the broth in the curved neck flask never became cloudy, but microorganisms built up at the bottom of the curve. this proved that microorganisms come from the air. -
Oparin and Haldane
Alexander Oparin and John B.S. Haldne both hypothesized (in the 1920s) that early air contained ammonia, hydrogen, water vapor, and methane. when these compounds were shocked with lightening, they created proteins -
Urey and Miller
Stanley Miller and Harold Urey conducted multiple experiments in 1953 based on the hypothesis of Oparin, They created many different organic compounds including amino acids -
Fox
Sydney Fox formed cells spontaneously from organic chemicals. these include microspheres and coacervates -
Cech
Thomas Cech found that some unicellular eukaryotes can use RNA as a catalyst, and that it acts similar to an enzyme. he coind the term ribozyme to describe this type of RNA molecule -
Radiometric Dating
Radiometric dating measures the age of an organism based on carbon-12 and carbon-14 amounts. carbon dating can be used for samples up to 60,000 years old. after that, an isotope with a longer half life (such as uranium) is needed
