Which temperature is used for denaturation in PCR?

Which temperature is used for denaturation in PCR?

• A. 95°C
• B. 60°C
• C. 72°C
• D. 37°C

Answer: (A)

The denaturation step uses a high heat to separate the two DNA strands. At around 95°C, the hydrogen bonds between complementary bases break, turning the double helix into single strands that the primers can later bind to. This high temperature is chosen because it reliably melts most DNA duplexes quickly and without damaging the template, allowing the next steps to proceed efficiently. Other temperatures in the cycle serve different roles: one lower temperature is used for primer annealing, where primers attach to their matching sequences, and another around 72°C is used for extension, where the polymerase adds nucleotides to build new DNA. A temperature like 60°C wouldn’t fully denature the strands, and 37°C is too low for standard denaturation in PCR.

The denaturation step uses a high heat to separate the two DNA strands. At around 95°C, the hydrogen bonds between complementary bases break, turning the double helix into single strands that the primers can later bind to. This high temperature is chosen because it reliably melts most DNA duplexes quickly and without damaging the template, allowing the next steps to proceed efficiently. Other temperatures in the cycle serve different roles: one lower temperature is used for primer annealing, where primers attach to their matching sequences, and another around 72°C is used for extension, where the polymerase adds nucleotides to build new DNA. A temperature like 60°C wouldn’t fully denature the strands, and 37°C is too low for standard denaturation in PCR.