DNA electrophoresis 238301 207506560 2008-04-23T01:48:27Z Soxred93 3010110 Reverted 1 edit by [[Special:Contributions/71.112.248.237|71.112.248.237]] to last version by Bobo192 [[Image:DNA Agarose Gel Electrophor.jpg|200px|thumb|right|Digital printout of an agarose gel electrophoresis of ''cat''-insert plasmid DNA]] [[Image:Electropherogram trace.jpg|thumb|200px|DNA electropherogram trace]] '''DNA electrophoresis''' is an analytical technique used to separate [[DNA]] fragments by size. An [[electric field]] forces the fragments to migrate through a [[gel]]. DNA molecules normally migrate from negative to positive potential due to the net negative charge of the [[phosphate]] backbone of the DNA chain. At the scale of the length of DNA molecules, the gel looks much like a random, intricate network. Longer molecules migrate more slowly because they are more easily 'trapped' in the network. After the separation is completed, the fractions of DNA fragments of different length are often visualizing a [[fluorescent dye]] specific for DNA, such as [[ethidium bromide]]. The gel shows bands corresponding to different DNA molecules populations with different molecular weight. Fragment size is usually reported in "nucleotides", "base pairs" or "kb" (for 1000's of base pairs) depending upon whether single- or double-stranded DNA has been separated. Fragment size determination is typically done by comparison to commercially available [[DNA ladder]]s containing linear DNA fragments of known length. The types of gel most commonly used for DNA electrophoresis are [[agarose gel electrophoresis|agarose]] (for relatively long DNA molecules) and [[polyacrylamide gel electrophoresis|polyacrylamide]] (for high resolution of short DNA molecules, for example in [[DNA sequencing]]). Gels have conventionally been run in a "slab" format such as that shown in the figure, but [[capillary electrophoresis]] has become important for applications such as high-throughput DNA sequencing. Electrophoresis techniques used in the assessment of [[DNA damage]] include [[alkaline gel electrophoresis]] and [[pulsed field gel electrophoresis]]. The measurement and analysis are mostly done with a specialized [http://www.labimage.net gel analysis software]. Capillary electrophoresis results are typically displayed in a trace view called an [[electropherogram]]. The DNA strand is cut into smaller fragments using DNA endonuclease, then samples of the DNA solution (DNA sample and buffer) are placed in the wells of the gel and allowed to run for some time (the less the voltage of the electophoresis, the longer time for the DNA sample to run through the gel, and this results in a more accurate separation). ==External links== * [http://www.gel-electrophoresis.com/gels/articles/dna-gel-electrophoresis/ DNA Gel Electrophoresis] [[Category:Molecular biology]] [[Category:Electrophoresis]] [[Category:DNA]]