Gel electrophoresis of nucleic acids

Digital printout of an agarose gel electrophoresis of cat-insert plasmid DNA

Gels of plasmid preparations usually show a major band of supercoiled DNA with other fainter bands in the same lane. Note that by convention DNA gel is displayed with smaller DNA fragments near the bottom of the gel. This is because historically DNA gel were run vertically and the smaller DNA fragments move downwards faster.

Nucleic acid electrophoresis is an analytical technique used to separate DNA or RNA fragments by size and reactivity. Nucleic acid molecules which are to be analyzed are set upon a viscous medium, the gel, where an electric field induces the nucleic acids to migrate toward the anode, due to the net negative charge of the sugar-phosphate backbone of the nucleic acid chain. The separation of these fragments is accomplished by exploiting the mobilities with which different sized molecules are able to pass through the gel. Longer molecules migrate more slowly because they experience more resistance within the gel. Because the size of the molecule affects its mobility, smaller fragments end up nearer to the anode than longer ones in a given period. After some time, the voltage is removed and the fragmentation gradient is analyzed. For larger separations between similar sized fragments, either the voltage or run time can be increased. Extended runs across a low voltage gel yield the most accurate resolution. Voltage is, however, not the sole factor in determining electrophoresis of nucleic acids.

单词	DNA electrophoresis
释义	DNA electrophoresis 英语百科 Gel electrophoresis of nucleic acids Nucleic acid electrophoresis is an analytical technique used to separate DNA or RNA fragments by size and reactivity. Nucleic acid molecules which are to be analyzed are set upon a viscous medium, the gel, where an electric field induces the nucleic acids to migrate toward the anode, due to the net negative charge of the sugar-phosphate backbone of the nucleic acid chain. The separation of these fragments is accomplished by exploiting the mobilities with which different sized molecules are able to pass through the gel. Longer molecules migrate more slowly because they experience more resistance within the gel. Because the size of the molecule affects its mobility, smaller fragments end up nearer to the anode than longer ones in a given period. After some time, the voltage is removed and the fragmentation gradient is analyzed. For larger separations between similar sized fragments, either the voltage or run time can be increased. Extended runs across a low voltage gel yield the most accurate resolution. Voltage is, however, not the sole factor in determining electrophoresis of nucleic acids.
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DNA electrophoresis

Gel electrophoresis of nucleic acids