What is the annealing temperature range for PCR?

The annealing temperature range for PCR (Polymerase Chain Reaction) is typically between 50°C and 70°C. This temperature range is crucial for the binding of the primers to the DNA template during the annealing phase of PCR. At these temperatures, the specificity of primer binding is optimized—high enough to allow for stable interactions between complementary sequences but low enough to prevent non-specific binding.

If the annealing temperature is too low, primers may bind non-specifically to regions of the template DNA, leading to non-specific amplification and reduced yield of the desired product. Conversely, if the temperature is too high, the likelihood of primer binding diminishes, which can significantly decrease the efficiency of the reaction.

Therefore, the temperature range of 50°C to 70°C is scientifically determined based on the melting temperatures (Tm) of the primers being used, and it balances specificity and efficiency, allowing for reliable amplification of the target DNA sequence in PCR.