RNA world hypothesis：RNA世界假说.ppt

Objectives: Be able to Summarize the Miller-Urey Experiment Relate the structure of Clay beds to the polymerization of nucleotides Understand the role of meteorite impacts in polymerization of Proteins Relate the structure of phospho-lipids to the formation of cell membranes. Two Characteristics of a Living Thing Must be able to store information (RNA or DNA) Express that information (proteins) Keratin: A hard durable protein found in Hair and Nails/Claws Proteases: Protiens that help digest proteins (meat) Actin /Mysosin: Proteins that are used in muscle fibers. Collagen: Found in connective tissue PSD-95: Protein that builds connections between synapses What came firstThe protein that makes up our body, or the RNA/DNA that codes for the protein? Conditions of the Early Earth Little oxygen in the atmosphere: Atmosphere is composed of CN, NH4, CH4, H2 Violent electrical storms Heavy Bombardment: A time when the earth is constantly hit with meteorites. Miller-Urey Experiment Adds early atmospheric gases to a flask connected to another flask with water (simulating the early oceans). Shot electrodes (simulate lightning) through the gases. Produced amino acids (building blocks of Proteins) from the gases. The Murchinson Meteorite In 1969 a meorite hit earth in Australia The meteorite was covered in thousands of amino acids, the building block of proteins. Panspermian hypothesis: that life actually originated in space and was brought to this planet. Experiments with Amino Acids under large impact pressures Scientist hypothesized that if amino acids were placed under meteorite impact pressure, then they would vaporize. The hypothesis was proved wrong: Amino acids Polymerized into long chains of protein. Dr. Jennifer Blank The Formation of Nucleotides Each of the 4 Nucleotides found in DNA: Adenine, Thymine, Cytosine, and Guanine have been synthesized in the laboratory using early atmospheric gases and an electrical discharge. Polymerization of Nucleo