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our solar system was a swirling mass of gas and dust and a few years later the sun started to form.
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earth began to form
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Earth probably appeared much as it does today.
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the oldest rocks and crystals are about 4 billion years old and
Volcanoes emitted gas, forming an atmosphere -
little or no oxygen gas existed in early earth, first cells might have developed in an environment with organic molecules for food
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some forms of life became photosynthetic
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ozone was made
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O2 levels reached today’s levels
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A type of small aerobic prokaryote was engulfed by and began to live and reproduce inside a larger, anaerobic prokaryote
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Ozone (O3) formed – protected organisms from harmful UV rays so they could exist on land
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First Microscopes- Robert Hooke used and early light microscope to study nature electron microscopes have also been used.
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Spallanzani’s experiment - he boiled broth in two flasks he kept one flask open and then sealed the other with melted glass. The broth within the sealed flask stayed clear but the broth within the open flask had turned cloudy. he inferred that microorganisms do not arise spontaneously, they are carried in the air.
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Radioactive dating-is used in methods of establishing the age of materials
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Urey and Miller- they tested Oparin’s hypothesis. They set up a chamber containing gases that Oparin believed to be in the atmosphere and as the gases circulated, electric sparks supplied energy to drive chemical reactions. The result of this experiment and others were a variety of organic compounds.
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Thomas Cech- showed that life could have started with RNA
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Oparin’s hypothesis was proposed in the 1920’s. They thought that early atmosphere contained ammonia, hydrogen gas, water vapor, and compounds made of hydrogen and carbon.
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Redi’s experiment- he took meat and put it in two beakers one sealed and one left open. The beaker left open had flies, but the sealed beaker would not let the flies enter. Redi concluded that the flies had something to do with the maggots that were shown with the sealed beaker.
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Pasteur’s experiment- he used a variation of Spallanzani’s experiment and used a cure-neck flask to heat the broth with and let it sit for one year. it was not sealed so the “spontaneous” force could get through but after one year the broth had stayed clear. Then when he broke the top off of the flask the broth became cloudy the next day.
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Lynn Margulis- a researcher that dealt with prokaryotic and eukaryotic cells.
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Fox-one of many who have done research on the physical structures that may have given rise to the first cells. Ex:Microspheres- which are composed of many protein molecules that are organized as a membrane, and Coacervates- which are collections of balls that are composed of molecules of different types.
