BIOL 1202 Lecture Notes - Lecture 4: Ammonia, Absolute Dating, Radiometric Dating
Document Summary
Chapter 25 the history of life on earth. Early earth: earth is about 4. 6 billion years (by) old. Radiometric dating of meteorites and moon rocks: life arose about 3. 8 by ago. Fossil bacteria in rocks 3. 5 by: no spontaneous generation now, but must have happened then. No free oxygen: abundant energy to drive reactions. Testable hypothesis explaining the origin of life: abiotic synthesis of small organism molecules, joining these molecules into polymers, packaging these molecules into (cid:862)protobionts(cid:863, the origin of self-replicating molecules. Miller and urey experiments: figure 4. 2. Alternative hypotheses: first organic compounds may have been synthesized near hydrothermal vents, extraterrestrial origin. Abiotic synthesis of polymers: small organic molecules polymerize when they are concentrated on hot sane or clay. Protobionts: aggregates of abiotically produced molecules surrounded by a membrane, liposomes can form when lipids or other organic molecules are added to water. Need proteins to synthesize more dna: then. Earliest cells used rna to store info.
