BIOL239 Lecture Notes - Electrophoresis, Globin, Cella
13 Sep 2014
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Short single-stranded stretches of dna of known composition. From 25 to several thousand nucleotides in length. To visualize them, the probes are labelled, usually with 32p or fluorescent dyes. Used in the identification of clones that contain complementary dna sequences: screening libraries by hybridization. Transfer colonies to a nylon membrane that fits right on top of the plate. Kill bacteria, make it single stranded, fix it to nylon so it doesn"t wash off and then probe with. It lyses the cells in situ (stay stuck). Dna goes from single to double stranded in naoh. Dry it and the dna will stay fixed to the filter in the same position it was on the original plate so now you can compare them. Put nylon filter into glad sandwich bag, add buffer as well as dna probe (red dots) and incubate overnight and the probe will hybridize to complementary sequences it finds.
