Bio 105 Chapter evolution reading

Bio 105 Chapter evolution reading - 448-466 Evolution Until...

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448-466: Evolution Until 1960s, was believed that earth formed from cosmic dust lying outside forming sun After Apollo, found that earth formed from accretion: gradual accumulation of material o Earth and other planets have been formed from accretion; the gradual accumulation of material Evolution: process in which existing life forms change in response to changes in their environment. In some cases, dramatic change leads to new species o 1. Organic molecules formed o 2. Cells evolved o 3. Multicellular organisms Chemical evolution: the formation of organic molecules from inorganic molecules is known as chemical evolution o Four billion years ago o Sunlight or other heat energized methane, ammonia, and hydrogen in seas—reacted w/ e/o, producing organic molecules (simple sugars & amino acids) o Chemical evolution: these organic molecules reacted with each other, forming polymers primitive RNA, DNA, proteins o Polymers combined to form first simple cells o Evidence:
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Miller: added methane, ammonia, & hydrogen to glass apparatus. Sparking device produced energy & steam. Days later, water turned brown & had in it many different compounds. Spontaneously assembled into long-chain molecules Panspermia hypothesis: chemical building blocks arrived from outer space o molecules essential to life arrived in meteorites & comets; however, chemical evolution still the main accepted explanation First cells: the earliest cells were probably aggregations of polymers that acquired nutrients directly from the environment. Aggregations of polymers & lipids in water o
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