Final answer:
During PCR, the temperature is set differently in each step. Denaturation step requires a high temperature to separate DNA strands, annealing step requires a lower temperature for primers to bind, and extension step requires an optimal temperature for Taq polymerase enzyme.
Step-by-step explanation:
The Polymerase Chain Reaction (PCR) is a technique used to amplify specific sections of DNA. PCR involves three steps: denaturation, annealing, and extension.
During denaturation, the temperature is set to around 94-96°C. This high temperature causes the double-stranded DNA template to separate into single strands, providing the starting point for the next steps.
Next, during the annealing step, the temperature is lowered to about 68°C. This allows the DNA primers to bind (anneal) to the complementary sequences on the single-stranded template DNA.
Finally, in the extension step, the temperature is set to around 72°C. At this temperature, the heat-stable Taq polymerase enzyme can extend the primers by adding nucleotides, synthesizing new DNA strands.
The temperature changes in each step are essential to achieve the specific tasks required for PCR, such as separating DNA strands, primers annealing, and DNA synthesis by the Taq polymerase enzyme.