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Download Proving Spontaneous Generation Wrong
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How old is the earth? • Currently humans have dated the earth to 4.5 BILLION years old. • We arrive at this date using Radiometric Dating Radiometric Dating • The radioactive decay (break down) of Uranium into Lead is used to date rocks. • Uranium turns into Lead at a constant rate so it is like an internal clock for rocks. • Half-life is 4.5 b.y. Proving Spontaneous Generation Wrong • In the 1600s Francesco Redi showed that maggots were the offspring of flies and did not simply form out of raw materials. Spallanzani’s Experiment • In the 1700s Lazzaro Spallanzani showed that microorganisms did not spontaneously form. Spontaneous Origin Not Spontaneous Generation • Life Sprang from a “primordial soup” of raw materials. • Materials found on the early earth were… • Nitrogen (N2) • Carbon Dioxide (CO2) • Methane (CH4) • Hydrogen (H2) • Ammonia (NH3) Miller-Urey Experiment • In 1953 Miller and Urey created an apparatus to make organic molecules out of raw materials found on the early earth. • Did create Amino Acids out of H2, CH4, and NH3 Chemosynthesis • Most scientists believe that the first cells that formed needed to form deep in the ocean around vents since the ozone layer had not formed yet. • The use of chemicals and heat to create sugar is called Chemosynthesis Cell Like Structures • Since Miller-Urey scientists have been able to create two different cell like structures out of raw materials that are very similar to cell membranes of today. • Microspheres and Coacervates RNA is Self Replicating • Many scientists believe that RNA was the first genetic information formed and ultimately led to heredity. First Photosynthetic Cells • The first photosynthetic cells to form were cyanobacteria. • The modern version of these bacteria are called stromatolites • Fossils of these bacteria date to 3.5 bya. Eukaryotes form from Prokaryotes • The current hypothesis for the formation of complex Eukaryotic cells is called endosymbiosis • Chloroplasts and Mitochondria used to be free living bacteria.
