BIO 200 Lecture Notes - Lecture 2: Precambrian, Protoplanetary Disk, Cambrian Explosion
27 Jun 2015
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Lecture 2: time scales and the origin of life. Hadean eon: no oceans, no free oxygen (oxygen bound by hydrogen or other substances, no protective atmosphere or ozone layer, susceptible to ultraviolet radiation. Proterozoic era: first multicellular life on earth, hard-shelled animals, unknown animal types (mostly extinct, trace fossils indicate capability for movement. Cenozoic era: age of mammals, current era. Origin of life: divine power (god) created life, panspermia: idea that life on earth originated elsewhere in space and travelled to earth, spontaneously formed by specific combinations of chemicals, earth 3. 8 billion years ago: High energy: early life was aquatic, two characteristics of life, organized: has a repeatable form, replicates itself: reproduction. Four steps to life: abiotic synthesis of organic molecules, the miller-urey experiment. Atmosphere similar to earth"s when first life formed recreated in lab. Reducing atmosphere: h2o, n2, nh3, co2, co, ch4, and h2. Liposomal cell has aqueous cavity that can hold other materials.
