01:119:115 Study Guide - Final Guide: Gram-Negative Bacteria, Vertebrate, Gram-Positive Bacteria
30 Oct 2014
School
Department
Course
Professor
Document Summary
Conditions on early earth: earth is about 4. 6 billion years old atmosphere had little free o2 no photosynthesis! Life can"t evolve in oxidizing atmosphere; must be reducing atmosphere. Instead the atmosphere had co2, h2o, h2, n2. Requirements for chemical evolution: absence of o2 energy chemical building blocks organic molecules sufficient time. Molecules formed near earth"s surface; sugars, nucleotides, amino acids formed spontaneously in the sea. Oparin and haldane hypothesis: abiotic synthesis of biological organic compounds. Miller and urey experimentally demonstrated that you can make amino acids abiotically 13 amino acids, glycine most abundant; nothing happened when o2 was added. Later stdies proved add hcn and you get adenine and other bases. Organic molecules formed abiotically at hydrothermal vents on the ocean floor. Rna world hypothesis: rna self-replicates, rna functions as both an enzyme and a substrate for replication. Ribozyme is enzymatic rna first step in evolution of dna/rna. Heterotrophs came first: they fed on organic molecules.
