How to Troubleshoot DNA Gel Electrophoresis
Gel electrophoresis is used in biology and can be used to separate DNA molecules according to size. A tray of gel with buffering solution is connected to an electric current which attracts the nucleic acid molecules of DNA. Shorter molecules travel more quickly than longer ones in the gel. Once the electrophoresis is complete, you should be able to view a pattern of bands on the gel which can be analyzed and used as data. However, there are instances when the results don't turn out as expected, but luckily, there are easy solutions for each type of problem.
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Instructions
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Complete the DNA gel electrophoresis process. If after 30 to 45 minutes there are no usable results, prepare to troubleshoot your experiment.
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If the bands are very faint or nonexistent, it's likely that there is a problem with the DNA sample. Try to increase the amount of DNA used while avoiding nuclease contamination, and be sure to use the correct buffer to prevent the DNA from becoming denatured. There is also a chance that the DNA was run off of the gel, so try to electrophorese for a shorter amount of time or lower the voltage.
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Smeared DNA bands may also indicate problems with the DNA. Be aware of nuclease contamination, correct buffering conditions, amount of salt present and the presence of excess proteins to prevent the DNA from being degraded or denatured. Too much DNA on the gel may also create smeared bands, so try to decrease the amount used.
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Sometimes you may notice that certain bands are missing from the results. If smaller bands are missing, they may have been pushed off of the gel. Try to use a lower voltage or decrease the time. If larger bands are missing, there is a chance that the components have not separated completely yet. This can easily be resolved by increasing the electrophoresis time.
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Inconsistent readings indicate problems with the electrophoresis process. Check to make sure the temperature of the gel and voltage are appropriate. Also, always use a sufficient amount of buffering solution.
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Tips & Warnings
Be patient even if you have to run the electrophoresis a few times. Keep in mind that different types of gel have different properties. Check for detailed information on your gel type prior to the experiment.
Be sure to use the electric source with caution.
