PCR Guide for beginners series: Electrophoresis bands analysis of PCR products

Agarose gel electrophoresis was usually performed after PCR amplification, and the following bands were usually found after electrophoresis:
1. Primer band. When the concentration of primers is over or the amplification efficiency is not special, the primers do not show thin bands, but diverge. If the target amplification product band and primer band are very bright, it can be considered to reduce the primer amount appropriately.
2. Primer polymer band. But if the amplified product is less than 100bp, the product and the primer polymer can not be separated, it is recommended to use DNA polyacrylamide electrophoresis (not protein SDS polyacrylamide electrophoresis); If the primer polymer still seriously affects the amplification of the target product after the renaturation temperature, consider replacing the primer design first (because the cost of primer synthesis is lower than that of the refolding condition).
3. Objective To amplify product bands. Its size is the same as the design size with clear strips.
4. Non-specific amplified product bands. Its size is not the same as the design size, the strip is clear. Generally, the renaturation temperature can be reduced or eliminated by the renaturation temperature (the renaturation temperature can also be found by the temperature gradient function, such as dongshenglong 811 PCR apparatus). If its fragment size is much larger than the target fragment, it can be reduced or eliminated by reducing the extension time (that is, not giving it enough extension time). Another non-specific amplification product band is the contamination of genomic DNA from reverse transcription PCR experiments. If the target amplification product contains introns, the target amplification product is likely to be larger than the target gene. Such bands cannot be eliminated by the renaturation temperature and can be sampled with RNase-free DNase prior to reverse transcription.
5. Template DNA band.