Normalisation; genomic DNA Targeting genomic DNA has also been suggested for normalisation.10 This appears to be an ideal method as it does not require reverse transcription for detection by real-time PCR. Cells that are proliferating are replicating their DNA, so contain more sets of genetic information when compared to nonproliferating cells. However, in eukaryotic organisms, this difference will usually be p2fold and so unless very fine measurements are required would not cause a problem. However, tumor cells often have a variable haplotype and actively replicating bacteria can contain up to 8 more copies of certain loci than nonreplicating cells.11 Another major problem with using this strategy is that RNA extraction proce
dures are usually not designed to purify DNA, so the extraction rate may vary between different samples, with DNA yields often being low.