Observe DNA bands, determine relative molecular mass, analyze band intensity and clarity, etc.

1. Observe DNA bands: In agarose gel electrophoresis, the size and number of DNA bands depend on the separation conditions and the characteristics of the DNA to be tested. By observing the size and number of DNA bands, the size, purity and quantity of the PCR product can be preliminarily judged.

2. Determine the relative molecular mass: Almost all agarose gel electrophoresis patterns contain molecular weight standards. By comparing the size and position of the standard band, the relative molecular mass of the DNA fragment to be tested can be determined.

3. Analyze the intensity and clarity of the band: The intensity and clarity of the DNA band reflect the content, purity and staining efficiency of the PCR product. If the band intensity is low and blurred, it is due to low PCR reaction efficiency or low DNA purity, and the PCR conditions need to be further checked and optimized.