Question

One typical PCR cycle lasts ______ minutes.
a) 1-2
b) 3-5
c) 5-10
d) 10-15

Answer 1

A typical PCR cycle, including ramping time and the three temperature stages, lasts about 3.75 minutes, so the correct answer is b) 3-5 minutes.

Step-by-step explanation:

One typical PCR cycle lasts for a total of about 3.75 minutes, which includes the time needed to reach each temperature during the steps of denaturation, annealing, and extension, as well as the time spent at each temperature. To break it down, the process goes through a denaturation phase at 92-97°C for 20 seconds, an annealing phase at 40-60°C for 20 seconds, and an extension phase at 65-80°C for 30 seconds. Therefore, the correct answer to the student's question would be b) 3-5 minutes. This efficiency is facilitated by the use of DNA thermal cyclers that can change temperatures quickly and precisely.