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October 1,3 2013 Chemical Evolution.docx

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Natural Science
NATS 1610
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The Living Body- L7 Chemical Evolution Tuesday/Thursday October 1,3 2013 -458-459 -How did life/cells begin? • We can never know the ancient events that produced life? We Don’t Know o But by applying the scientific method we can develop hypothesis o That are at least partly testable through experiments o The hypothesis proposed to explain the origin of life  Are modified as new information is uncovered -Life is thought to begun between 3.5-4 billion years ago • Mostly an educated guess • Oldest fossils about 3.5 billion years old -some theories for the origin of life 1. Life was created by the action of one or more gods • Not testable, reliable on faith • Science seeks natural causes for natural phenomenon • Beyond scope of this class 2. Life originated from non-living matter on earth • Spontaneous generation • Chemical evolution • Hydrothermal vents 3. Life on earth came from some other place in the universe • This only moves problem to somewhere else -Spontaneous Generation Theory: that some life forms came out of nothing • Ex. Fleas from dust, maggots from dead fish, mice from stored grain or cheese wrapped in rags • This theory was made obsolete by the work of a Pasteur and others • Pasteur conducted a famous experiment in 1859 o To test if living matter can be created from non-living matter o He first showed that air is full of microorganisms o Passed air through cotton fibers  The cotton trapped tiny particles floating in the air o Dissolved the cotton using a mixture of ether and alcohol  Left the particles that settled to the bottom of the liquid o Upon microscopic examination  These particles reveals numerous microorganisms that resembled others o Pasteur Next showed that spontaneous generation does not occur o Two flasks that were sterilized, but one had a goose neck on it not allowing air to directly get to it o The one open directly open to the air become foggy or infected o The other container did not go foggy (stayed sterile) because microorganisms could not get into the flask o Proving that there is microorganisms in the air -Condition of Primitive Earth • Earth had cooled down, but still intense energy sources (lightening, volcanic activity, ultraviolet sunlight) o Enormous thunderstorms caused primordial oceans, lakes and lagoons • Atmospheric gases mainly from volcanic eruptions (outgassing) • Little or no atmospheric oxygen • Could a form of “molecular” spontaneously generation have occurred under all of these conditions? -Chemical Evolution Hypothesis: suggests life (and cells) evolved from chemicals…. As chemical com
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