The bands of dna electrophoresis can only be seen under ultraviolet light. The principle of dna electrophoresis is that dna fragments with different lengths migrate in agarose gel under the same electric field force, and the shorter the length, the faster the migration distance, that is to say, the smaller the fragment, the lower the gel.

Generally, dna electrophoresis should be run with marker in addition to the sample, which is composed of several dna fragments with known fragment sizes. With dna electrophoresis bands as reference, the size of DNA fragments in the sample can be roughly judged. And because the dan fragment in marker is also quantitative.

Extended data:

Precautions:

In general, a comb with a width of 0.5cm can add 0.5g of DNA, and the amount of sample added depends on the size of the sample adding hole and the number and size of DNA fragments. When the loading hole is large, the loading amount of the sample should be increased accordingly, otherwise the band will be shallow or even unclear, otherwise the loading amount should be reduced appropriately, but too much loading amount will cause the loading hole to be overloaded, which will lead to tailing and dispersion, especially for larger DNA.

The salt concentration in DNA samples will affect the mobility of DNA, and the same buffer conditions should be used for parallel control samples to eliminate this influence. The mobility of DNA depends on the concentration of agarose gel, the shape and size of migrating molecules.

It is possible to distinguish a wide range of DNA molecules by using gels with different concentrations. The concentration of gel can be determined according to the range of DNA molecules when preparing agarose gel. Polyacrylamide gel electrophoresis should be used for DNA electrophoresis of small fragments to improve the resolution.

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