Question

In a typical microbiology laboratory, reasons for no bands from a gel of a polymerase chain reaction may be due to errors relating to omission of ingredients in the reaction mix and absence of the target sequence in the template DNA. Based on (i) primer problem and (ii) purity/potential contamination of the target sequence, explain the reasons for non-appearance on bands.

Answer 1

There are so many possible causes for no bands from PCR. No bands from a gel of a polymerase chain reaction may be due to following errors; i) primer problem and (ii) purity/potential contamination of the target sequence. Contaminant primer may inhibit PCR. Successful amplification depends on the quantity and quality of DNA template. Using insufficient template or excess template will cause no bands condition. The primer concentration was too low or unbalance / excessive concentration of primers also leads to no bands on gel. Contaminants in the dNTP mix can leads to no band formation by PCR inhibition.