So in a laboratory, because we know what the flanking sequence is, we can basically build the DNA primers that will bind onto the three end of our DNA strands. So that is shown in the following diagram. So step two is annealing of the DNA primers, the heated DNA solution. Now it's cooled to a temperature of about 54 degrees Celsius. And that's just the right temperature for those DNA primers to actually anneal and hybridize with the three ends of those DNA strands that are now single strands. And notice these two strands of DNA will not form the hydrogen bonds because now we're going to have many of these DNA primers floating around and in between our two DNA strands.