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Diversity Part 1

Diversity Part 1 - Diversity(Chapters 11 Early Life Planet...

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Diversity (Chapters 11) Early Life 1. Planet Earth is at least 4 billion years old 2. First evidence for microbial life can be found in rocks about 3.86 billion years old 3. Stromatolites are fossilized microbial mats consisting of layers of filamentous prokaryotes and trapped sediment. o The phototrophic green nonsulfur bacterium Chloroflexus is similar to the filamentous prokaryotes that form the primitive microbial mats. 4. Early Earth was o anoxic o Much hotter than the present Earth o Abiotic synthesis of first biochemical molecules 5. Early Earth conditions suggest that primitive metabolism was o Anaerobic o Chemolithotropic (FeS and H 2 S) o Autotrophic 6. 2.8 billion years ago there was a shift from anoxic to oxic environment. (11-8) o Oxygenic phototrophic cyanobacteria were the first microorganisms capable of generating oxygen. o As oxygen accumulated in the atmosphere, an oxic environment like the present was created. o O 2 reacts with short wavelength UV radiation to form ozone (O 3 ) which acts like a shield to protect the Earth from intense UV radiation emitted by the sun. Phylogeny & Taxonomy 7. Phylogeny - evolutionary relationships of organisms. 8. Phylogeny is measured by evolutionary chronometers that are typically housekeeping genes essential for a cell such as ribosomal RNAs or ATPase proteins and others o Sequence comparison used to determine the evolutionary distance between organisms o By comparing a gene’s sequence amongst many organisms, scientists can determine how
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