So this allows us to basically study how gene expression takes place and how we synthesize and which proteins we actually synthesize. Now this also leads us into factor number three. So now that we know what the specific nucleotide sequence of that DNA molecule is we can now synthesize that DNA molecule from scratch in the laboratory by using a method known as solid state method. Now, once we synthesize that DNA molecule of interest, what do we do next? Well, that leads us into factor number four. We have a process known as the polymerase chain reaction or simply PCR that allows us to amplify a single DNA molecule.