<P> 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 ( which are negatively charged due to their sugar - phosphate backbone ) to migrate toward the anode ( which is positively charged because this is an electrolytic rather than galvanic cell ) . 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 . </P>
<P> 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 ( which are negatively charged due to their sugar - phosphate backbone ) to migrate toward the anode ( which is positively charged because this is an electrolytic rather than galvanic cell ) . 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 . </P>
why do longer dna molecules move more slowly than shorter ones during electrophoresis
why do longer dna molecules move more slowly than shorter ones during electrophoresis
resistance
resistance