2009 (1) - Chapter 26: The Tree of Life: An Introduction to...

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Chapter 26: The Tree of Life: An Introduction to Biological Diversity
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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
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Origin of Earth (overview) Singularity: Pre-Big Bang Inflation: Energization of Big Bang Universal expansion: Energy provided by Inflation Sub-atomic particles: Energy 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)
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Origin of Life (overview) 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 replication 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 eukaryotes Endosymbiosis: Further increase in eukaryote complexity and expansion of biochemistry Multicellularity: Cooperative grouping of differentiated, clonally related cells
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Logic of Origin of Life Large volumes quantitatively lots of (large numbers of) experiments Diverse environment qualitatively lots of (high diversity of) experiments Lots of Time 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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2009 (1) - Chapter 26: The Tree of Life: An Introduction to...

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