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Unformatted text preview: quence will be cut to pieces. My DNA computer did not use restriction enzymes, but they have been used in subsequent experiments by many other research groups. 5. Gel electrophoresis. This is not stolen from the cell. A solution of heterogeneous DNA molecules is placed in one end of a slab of gel, and a current is applied. The negatively charged DNA molecules move toward the anode, with shorter strands moving more quickly than longer ones. Hence, this process separates DNA by length. With special chemicals and ultraviolet light, it is possible to see bands in the gel where the DNA molecules of various lengths have come to rest. 6. DNA synthesis. It is now possible to write a DNA sequence on a piece of paper, send it to a commercial synthesis facility and in a few days receive a test tube containing approximately 1018 molecules of DNA, all (or at least most) of which have the described sequence. Currently sequences of length approximately 100 can be reliably handled in this manner. For a sequence of length 20, the cost is about $25. The molecules are delivered dry in a small tube and appear as a small, white, amorphous lump...
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- Fall '08