This illustration shows the process of reverse transcription polymerase chain reaction (RT-PCR). a double stranded DNA is transcribed via tRNA that binds to the PB site on the mRNA strand. As the first DNA strand is formed the mRNA strand degrades. Once the second complementary strand of DNA is formed from the last remaining PP site of the mRNA, the double stranded DNA is formed. This is the reverse transcription (RT) phase. Then the polymerase chain reaction (PCR) portion starts. In the Initiation and denaturation phase, the double stranded DNA is seperated by heat which degrades the hydrogen bonds attaching the two strands. With subsequent cooling, the primers and polymerase are able to bind to the single strands of DNA which allow the complementary DNA strand to form during the Annealing and Elongation phase. The result is two complete DNA strand clones from the original DNA template. The PCR process is repeated causing an exponential amplification chain reaction resulting in multiple copies of the original double stranded DNA.