How many primers are used in standard PCR?

How many primers are used in standard PCR?

• A. 1
• B. 2
• C. 3
• D. 4

Answer: (B)

Two primers are used. In standard PCR, a pair of short DNA sequences, called forward and reverse primers, bind to opposite ends of the target region. They define the start and end points for DNA synthesis. DNA polymerase extends from the 3′ ends of both primers, creating new strands and copying the segment between them. Each cycle doubles the amount of target DNA, yielding exponential amplification of the defined region. If only one primer were used, amplification would be limited to linear rather than exponential growth because a single primer can only initiate synthesis on one strand. Using a pair of primers ensures precise, defined amplification of the desired DNA fragment.

Two primers are used. In standard PCR, a pair of short DNA sequences, called forward and reverse primers, bind to opposite ends of the target region. They define the start and end points for DNA synthesis. DNA polymerase extends from the 3′ ends of both primers, creating new strands and copying the segment between them. Each cycle doubles the amount of target DNA, yielding exponential amplification of the defined region. If only one primer were used, amplification would be limited to linear rather than exponential growth because a single primer can only initiate synthesis on one strand. Using a pair of primers ensures precise, defined amplification of the desired DNA fragment.