16.3 - In vitro gene cloning - the polymerase chain reaction

The process is carried out in 3 stages:

1. separation of the DNA strand. The DNA fragments, primers and DNA polymerase are placed in a vessel in the thermocycler. The temperature is increased to 95oC, causing the two strands of the DNA fragments to separate.
2. addition (annealing) of the primers. The mixture is cooled to 55oC, causing the primers to join (anneal) to their complementary bases at the end of the DNA fragment. The primers provide the starting sequences for DNA polymerase to begin DNA copying because…