1 - 1.2.3 Statistical impossibility of proteins? What about...

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1.2.3 Statistical impossibility of proteins? What about the argument concerning the statistical improbability of obtaining a specific 141 amino acid sequence by looking for the correct sequence among randomly generated sequences? Certainly this mechanism could not explain the origin of protein sequences, but the creationist suggestion that this mechanism is part of evolutionary theory is false; it is a "straw-man" -- a false creationist caricature of evolution -- used repeatedly by creationists to mislead naive audiences into thinking that evolution is illogical. It is false because it demands a specific sequence in a SINGLE selection step from a pool of random sequences, whereas the real evolutionary model for the origin of protein sequences involves MULTIPLE ROUNDS OF RANDOM MUTATION followed by MULTIPLE selection steps as outlined above. In a beautiful discussion of the distinction between these two models, British biologist Richard Dawkins (The Blind Watchmaker New York, 1986) simulated the creationists' straw-man caricature on a computer. He programmed the computer to generate random sequences to see if it would ever generate a line from Hamlet: "Methinks it is a weasel." This line has 28 characters (including spaces), so the computer was programmed to make 28 selections from the 27 possible characters (26 letters plus space). A typical output was MWR SWTNUXMLCDLEUBXTQHNZVJQF Since there are 27 28 different possible ways of choosing from 27 alternatives 28 times, one can calculate the probability of picking the correct sequence and, based on the speed of the computer, estimate how long on average one would have to wait for the correct sequence to be printed. Dawkins figured a million million million million million years. If this were the best way protein
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This note was uploaded on 11/14/2011 for the course BIO BSC1010 taught by Professor Gwenhauner during the Fall '10 term at Broward College.

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1 - 1.2.3 Statistical impossibility of proteins? What about...

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