Final answer:
The elongation step of the PCR process involves raising the temperature to approximately 72°C to enable Taq polymerase to synthesize new DNA strands by adding nucleotides to the annealed primers. This is part of a cycle including denaturation and annealing, and the steps are repeated to exponentially amplify the DNA.
Step-by-step explanation:
Elongation Step of PCR
During the elongation step of the Polymerase Chain Reaction (PCR), the temperature is raised to approximately 72°C. This is the optimal temperature for the activity of Taq polymerase, a heat-stable DNA polymerase.
At this stage, Taq polymerase adds nucleotides to the primer using the single-stranded target DNA as a template, thus creating new DNA fragments.
The PCR process involves initial denaturation of the target DNA at a temperature ranging from 92 to 97°C, then annealing of primers at a lower temperature (typically around 55°C), and finally, the elongation phase at around 72°C.
These steps are performed in a cyclical fashion, typically 20-40 cycles, resulting in an exponential increase in the specific target DNA fragment. The elongation process is vital as it is the actual synthesis phase where the DNA is replicated.