Question

Explain at least one possible reason why you might have the following results in an agarose gel electrophoresis of your PCR products. In addition to your DNA PCR sample, you also ran a Hi-Lo Marker, a positive PCR control, and a negative PCR control. 16. Scenario C: Your Hi-Lo marker showed up but there were no bands in the lanes for your PCR positive control, DNA PCR sample or negative PCR control.

Answer 1

Ans;- Hi-lo marker contains different size of DNA so it is meant to be showed up. it will produce ladder of band. each band has different base pair and size. Hi-lo can be use to detect size of sample DNA which is being tested in PCR. positive control is design in a way that it produce band so it is normal that we will get band in positive control. negative control designed to produce no band on gel electrophoresis. so above three results are normal feature of PCR gel electrophoresis. now problem is that we do not have any band in our DNA sample lane, reason could be template DNA has degraded, Primers have degraded, PCR inhibitors and polymerase enzyme has not worked properly. lets discuss what happens if template DNA has degraded. DNA template is fragment of DNA where polymerase enzyme bind and produce another fragment of DNA. as this reaction happens in repetitive it produce large amount DNA in relatively short period of time (DNA amplification). these DNA fragment we can detect by running our sample on gel electrophoresis if reaction has completed properly. here we have no band in DNA sample lane it could be because of template DNA degradation.