Unit 10: Origin and History of Life Hypothesis on the Origin of Life • The production of simple cells –Abiotic synthesis of small organic molecules –Macromolecules –Protocells –Self-replicating molecules Abiotic Synthesis of Organic Polymers • Oparin and Haldane – Early Earth • Reducing atmosphere • Energy • Miller and Urey – Primordial environment • Formed organic compounds Other Supporting Evidence • Abiotic synthesis of macromolecules – 2009 study • Protocells – Vesicles • Self-replicating RNA – Ribozymes – RNA world How Life May Have Emerged • Volcanoes released gases – Atmosphere formed • Gases condensed • Organic molecules – Energy – Joining of inorganic molecules • Polymers and self-replicating molecules – Dehydration reactions How Life May Have Emerged • Protobionts – Unable to reproduce – Can carry out chemical reactions • Heterotrophic prokaryotes – Limited recources – Anaerobic • Autotrophic prokaryotes – Mutations How Life May Have Emerged • Oxygen and ozone – Product of photosynthesis • Eukaryotes appeared – Symbiotic relationships • Life evolved – Natural selection Geologic Time Scale Endosymbiotic Theory Fossil Evidence for the History of Life • See textbook on page 511, Figure 25.4 Continental Drift Mass Extinctions • 5 major mass extinctions – Permian • Pangaea • 96% loss of marine animal species – Cretaceous • Volcanic eruptions in Siberia • Global warming and drop in oxygen • Loss of 50% marine and many terrestrial plant and animal families, including dinosaurs The 6th Mass Extinction • Human Impact – Habitat destruction – Industrialization • Recovery – 5 to 10 million years Phylogenic System of Classification • Previous Systems – 5 kingdom system – 6 Kingdom system • Current System – 3 domain system Three Domain System Three Domain System • Characteristics of the universal ancestor • Different conclusions • Evidence Adaptive Radiation Reproductive Barriers