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Unformatted text preview: tube. Warm conditions encourage the DNA polymerase to begin duplicating; a hotter environment causes the resulting annealed strands to split from their double-helix structure, enabling subsequent replication of the individual pieces.
60 Scientific American August 1998 The result was that molecules with both the right start and end cities were reproduced at an exponential rate. In contrast, molecules that encoded the right start city but an incorrect end city, or vice versa, were duplicated in a much slower, linear fashion. DNA sequences that had neither the right start nor end were not duplicated at all. Thus, by taking a small amount of the mixture after the PCR was completed, I obtained a solution containing many copies of the molecules that had both the right start and end cities, but few if any molecules that did not meet this criterion. Thus, step 2a of the algorithm was complete. Next, I used gel electrophoresis to identify those molecules that had the right length (in the example on page 56, a length of 24). All other molecules were dis...
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- Fall '08