The final step is the extending stage, where Taq polymerase enzyme starts from the primers and uses the deoxynucleotide triphosphates, also known as dNTPs or DNA nucleotides, to build the complementary strand of the single-stranded DNA. Taq polymerase, named after Thermus aquaticus, is a thermostable DNA polymerase that works best at higher temperatures compared to other polymerases . The optimal temperature for the enzymes is 72°, but the extending stage may be between 30°C to 90°C for less timing dedicated towards change in temperature from the previous stage. All the three steps, denaturation, annealing, and extension, make up one cycle, and PCR usually runs for 25-35 times for the best output. However, according to Thermo Fisher Scientific (n.d.), it may be required to run more than 40 times if the DNA copy is fewer than 10 copies but less than 45 cycles due to the appearance of nonspecific products. To synthesize cDNA from RNA, either the non-sequence specific primers or sequence-specific primers is used . After the reverse-transcription, the cDNA will be used as a template for PCR.