Final answer:
The three main steps of PCR are denaturation, annealing, and extension, which occur at different temperatures. The denaturation step separates the DNA strands, the annealing step allows primers to bind to the template, and the extension step synthesizes new DNA strands at the primers.
Step-by-step explanation:
The polymerase chain reaction (PCR) involves three main steps: denaturation, annealing, and extension. Each step occurs at a different temperature. The denaturation step occurs at a high temperature, typically around 94-96°C, where the double-stranded DNA template is separated into single strands. The annealing step occurs at a lower temperature, usually around 55°C, where the DNA primers bind to their complementary sequences on the single-stranded template. Finally, the extension step occurs at an intermediate temperature, typically around 72°C, where the heat-stable enzyme Taq polymerase adds nucleotides to the primers, resulting in the synthesis of new DNA strands.