ACCT 2001 Chapter : Chap004
Document Summary
1/30/2013: earth is about 4. 6 billion years old, radiometric dating of meteorites and moon rocks. Life arose about 3. 8 billion years ago: chemical traces in rocks 3. 8 billion years, fossil bacteria 3. 5 billion years, no spontaneous generation now, but must have happened then. Concerns on early earth: atmosphere, co2; ch4; nh3; h2s; h2o, no free oxygen, abundant energy to drive reactions, frequent storms with much lightning, frequent volcanic eruptions, frequent meteor impacts, uv light from the sun. Joining these molecules into polymers: abiotic synthesis of small organic molecules, packaging these molecules into protobionts , the origin of self-replicating molecules. Miller and urey experiments: used an apparatus filled with simple gases (like those in early atmosphere, had electrodes shock the apparatus, organic molecules (amino acids) appear after only a few days. Alternative hypothesis: first organic compounds may have been synthesized near hydrothermal vents, extraterrestrial origins, meteorites and comets hit the earth and bring with them organic material.
