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Early Earth and the Origin of Life Logical Progression Possible Scenarios Supporting Data Problems Abiotic Synthesis of Monomers Reducing Atmosphere Deep Sea Outer Space Miller -Urey Experi ment Imbedded organic compounds found in vents Organics found in meteors and comets Abiotic Synthesis of Polymers Concentrated hot monomers form polymers as evaporation and cooling takes place Process fits all scenarios above but differs in location Minerals, clay, “pyrite” , iron & nickel sulfides could be used as catalysts Monomers form polymers when dripped on hot sand, rock, or clay Polymers have been found embedded in deep sea vents Origin of Genetic Informati on “It’s an RNA world” RNA was the first genetic molecule(genotype ) that functioned also as an enzyme (phenotype) Natural selection picked the best RNA molecules as it replicated and “metabolized” available monomers RNA-amino acid interaction by molecular cooperation Short sequences of RNA can replicate with zinc as catalyst RNA can act enzyme like (ribozyme) RNA types allow natural selection Formation of Protobiont s membrane bound “cells” with some properties of life Abioticly produced molecules interact to maintain a constant internal environment showing irritability and metabolism Protobionts called Liposomes form from lipid, COH, and protein that have: 1. Lipid bilayer that shows osmosis 2. Voltage across membrane (membrane potential) 3. Engulf and split 4. Simple metabolism A.A. Protein Sugar Starch NucleotidesDNA C+H+N+O Amino acids simple sugars lipids H20,H, CH4, NH3 + Energy amino acids. Nucleotides sugars Vents used iron and sulfur and hot water to build from CO2 and ammonia Comets, meteors, space dust showered earth with organic molecules 3.5 bya fossilized stromatolites (layered clay rock) formed by 1 st prokaryotes
