What result could you expect if you replaced human DNA for b

What result could you expect if you replaced human DNA for bacterial DNA in a PCR reaction?

Solution

Quality of PCR depends on what type of DNA is used as a template in PCR. If bacterial DNA is of plasmid type, then we need around 1 pg to 10 ng of DNA in a 50 uL reaction mixture. But if it is bacterial genomic DNA, then we need around 1 ng of DNA. Again, if it is human genomic DNA, we need around 100 ng to 1 ug of DNA as template.

Bacterial DNA comprises a much smaller genome compared to human DNA. So, if we compare two PCR, where in one, 100 ng of bacterial DNA and in the other 100 ng of human DNA is used, the former will have much more copies of a specific common gene, compared to the latter. One has to be careful regarding concentration of the template DNA, as oversaturation of template DNA may yield poor results.

One very important thing to keep in mind though. Unless the gene is highly conserved throughout evolution of all organisms, the higher oligomer primer used for human gene amplification won\'t amplify any bacterial DNA sequence. Again, if it\'s any random hexamer, octamer, etc as used in RAPD, then in both cases ther will be multiple amplified products.