2005_campbl26

2005_campbl26 - Origin of Life (overview) An overview of...

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1 Chapter 26: The Tree of Life: An Introduction to Biological Diversity Origin of Life (overview) ± We will concentrate in this lecture on three things: ± An overview of the logic of the origin of life Where did the earth of Earth/what is the history of life’s origins? How is it possible that life could form? Why doesn’t life arise de novo today? ± Fossilization How do fossils form? What can go wrong? How do we date them? ± An overview of the diversity of life Problems with the the Five-Kingdom system The three-domained universal tree The n -Kingdom “system” of organismal classification Origin of Earth (overview) ± Singularity: Pre-Big Bang ± Inflation: Energization of Big Bang ± Universal expansion: Energy provided by Inflation ± Sub-atomic particles: Energy Æ Mass conversion as universe cooled ± Atoms: mostly Hydrogen ± Gas-cloud inhomogeneities: provided gravity wells ± Stars: gas-cloud gravitational collapse ± ± Metals: Atoms other than H and He ± Molecules: More complex than H 2 ± Accretion: Formation of planets ± Planets: gravity wells (like stars but smaller) ± Planets: solid substrate upon which life can evolve ± Chemical evolution: Formation of more-complex chemicals, in space or on planets ± Replicators: Chemicals capable of templating their own replicaiton ± Separate phenotype: Molecules responsible for some phenotype are other than those carrying genotype ± Individuality: Protocells then cells (more complex phenotypes can evolve if not shared between replictors) ± Prokaryotes: Earliest true cells (~3.5 bya) ± Endomembrane system: Increase in cellular morphological complexity Æ eukaryotes ± Endosymbiosis: Further increase in eukaryote complex and expansion of biochemistry ± Multicellularity: Cooperative grouping of differentiated cells ± Etc.: Plants, Fungi, Animals Logic of Origin of Life ± Large volumes Æ quantitatively lots of (large numbers of) experiments ± Diverse environment Æ qualitatively lots of (high diversity of) experiments ± Lots of Time Æ perhaps hundreds of millions of years Diverse, numerous experiments plus potential for experiments to build upon each other (evolution) ± Not-oxidizing atmosphere
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2005_campbl26 - Origin of Life (overview) An overview of...

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