lecture 3, evolution fall 2011

lecture 3, evolution fall 2011 - Hopanoids (membrane...

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Unformatted text preview: Hopanoids (membrane components of some bacteria) found in sedimentary rock are an example of a Microfossil Biosignature Stromatolite Banded iron formation Prebiotic metabolite The geological record shows evidence of microbial life on earth about how many billion years ago? 0.1 1.0 3.0 500 1000 Microbial evolution Evolution is the emergence of new species as a consequence of natural selecton The universal ancestor What characteristics did the universal ancestor have? Shared properties of all three domains of life Genetic code, fueling pathways, protein synthesis, cell structure, . Simple or sophisticated Sudden evolution Universal ancestor The first living entity must have been simple, possibly too simple to be called an organism, some use the term progenote. All hypotheses of the origin of life share the supposition that Molecular components of living things must have accumulated: purines, pyrimidines, amino acids, etc. Guessed wrong on early earth gas composition Similar to Darwins warm little pond Progenotes likely carried out essential processes inefficiently by current standards but little competition. High rate of mutation, rapid evolution Explosive evolution Punctuated equilibrium proposes that stasis is broken by rare events of large change, characterised by rapid events of branching speciation Charles Darwin On the Origin of Species by Means of Natural Selection Darwin Days on campus Darwin proposed that evolution proceeds by natural selection, which, by acting on naturally occurring variation within populations, favors advantageous characteristics. Two weeks before his death, Darwin published a paper on a tiny clam associated with the leg of a water beetle. The beetle was sent to him by Walter Crick, an amateur naturalist. Walters grandson was Francis Crick who in 1953 with James Watson discerned the structure of DNA vindication of Darwins beliefs regarding evolution. Modern Darwins To understand the story of evolution- both its narrative and its mechanism- modern Darwins dont have to guess. They consult genetic scripture. National Geographic, Feb. 2009 In the beak of the finch and the fur of the mouse,...
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This note was uploaded on 11/30/2011 for the course MICROBIO 303 taught by Professor Kaspar/escalnte/downs during the Fall '09 term at Wisconsin.

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lecture 3, evolution fall 2011 - Hopanoids (membrane...

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