24 25 Oct 2010

24 25 Oct 2010 - Purified DNA forms a viscous slurry that...

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Purified DNA forms a viscous slurry that can be drawn in fibers The viscosity of DNA decreases when temperature is increased DNA duplexes denature (melt) near the boiling temperature of water As temperature is lowered, the DNA duplex anneals in a biphasic process The slow phase is alignment of complementary segments, the fast phase is annealing of adjacent sequence The melting process can be followed using absorption spectroscopy Hypochromicity = base stacking in duplex lowers extinction coefficient
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The melting temperature is the half way point in the transition GC base pairs, with three H-bonds, adds stability AT rich genomes have lower melting temperatures
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Partial denaturation has been visualized using electron microscopy Bubbles of single stranded DNA were trapped by fixatives Single stranded regions are fragile and avoided by interaction with single-stranded DNA binding proteins
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Before genomes could be compared using sequence databases, a technique known as hybridization was used Two different denatured genomes were allowed to anneal together and overlap measured The technique is still useful in “fishing” for mRNA
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Accumulation of errors results in corruption of gene sequences
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24 25 Oct 2010 - Purified DNA forms a viscous slurry that...

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