Practice question

Polymerase chain reaction demands rapid, precise transitions between denaturation near 94°C, annealing at 50-65°C, and extension at 72°C for 30-40 cycles. Thermal cycler uses Peltier elements and engineered aluminum blocks to achieve ramp rates of several degrees per second, ensuring uniform heating and cooling of microliter volumes in tubes. This automation eliminates manual water bath transfers, improves reproducibility, and enables hot-lid technology to prevent evaporation. It does not perform electrophoresis or single-step incubation, but orchestrates complete temperature profile required for exponential DNA amplification.