Question

PCR amplified DNA on agarose.

Will DNA with no mutation in codon (wild-type) show up on gel electrophoresis? How can I predict bp?

Thanks

Answer 1

Assuming that you have performed PCR to find the mutants or the SNPs and wish to know if wild type DNA would occur or not.

The primers we use in such PCR reactions are called mismatch primers that are complementary to the template strand except for one nucleotide which serves as the SNP giving the mutant form of DNA.

However, some wild type sequences can still be amplified when exonuclease activity of taq enzyme allows the extension. So, yes the wild type DNA can show up in gel electrophoresis.

To detect such wild type DNA products, one needs to compare it with the ladder DNA and check the amplicon size. This would be different from the mutant one. Now, the primers have to be checked and theoretical product size has to be estimated. If two concur, then the amplified DNA is of wild type.