Question

what are the main steps of pcr? 1. primer annealing at 55 to 65 oc 2. after one cycle, dna molecules are doubled 3. denaturation of the dna at 94 to 98 oc 4. primer extension at 72 oc

Explanation:

PCR (Polymerase Chain Reaction) is a technique used to amplify DNA. The main steps are:

• Denaturation: DNA is heated to 94 - 98°C to separate the double - stranded DNA into single strands.
• Primer annealing: Primers bind to the single - stranded DNA at 55 - 65°C.
• Primer extension: DNA polymerase extends the primers at 72°C to synthesize new DNA strands.

Answer:

The correct order of the main steps of PCR is 3 (Denaturation of the DNA at 94 to 98°C), 1 (Primer annealing at 55 to 65°C), 4 (Primer extension at 72°C). Step 2 (After one cycle, DNA molecules are doubled) is a result of the PCR cycle rather than a main step in the process.