Chapter 6 Book Notes

Miller urey experiment support the idea that organic

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Miller-Urey experiment: support the idea that organic compounds would have formed spontaneously and in vast quantities on early Earth covering our planet and filling at least the top layers of the oceans with a rich “organic soup” containing all building blocks of life Issue over atmosphere Chemical reactions near deep-sea vents Organic molecules may have been material from space Many impacts from bombardments could have brought additional organic material from asteroids and comets RNA is simpler than DNA because it has only one strand rather than two and its backbone structure requires fewer steps in its manufacture RNA cannot replicate without enzymes and enzymes cannot be made without RNA BUT RNA could have served as both genes and as chemical catalysts for copying and expressing those genes (RNA world) RNA assembly would require some sort of catalytic reaction to facilitate it Clay minerals contain layers of molecules to which other molecules can adhere Experiments suggest that clays in Earth’s early oceans could have served as natural chemical “factories” that could have produced self-replicating molecules of RNA
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Confining early molecules within pre-cells would help If we cool a warm-water solution of amino acids, they can form bonds among themselves to make an enclosed, spherical structure Conclusion: DNA evolved from RNA. Could life have migrated to Earth? Migrate to earth by meteorites (Panspermia) Venus, Mars, and Earth Conclusion: Life arose on Earth quite soon after conditions first allowed it, and even if life migrated here from another world, we have good reason to think that it evolved naturally, through chemical processes that favor the creation of complex, organic molecules and the subsequent molecular evolution of self-replicating molecules. What major events have marked evolutionary history? Life has been evolving throughout the 4 billion or so years during which it has existed on Earth Anaerobic: does not require molecular oxygen Aerobic: cannot survive without molecular oxygen Photosynthesis – 3.5 billion years ago
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