PCR relies on which principle and what are the core steps in a cycle?

PCR relies on which principle and what are the core steps in a cycle?

• A. Amplification via random duplication; product remains constant.
• B. Denaturation, annealing, and extension using DNA polymerase and primers; exponential replication of target DNA.
• C. Digestion with nucleases followed by ligation; no amplification.
• D. Sequence-specific degradation in cycles.

Answer: (B)

PCR relies on exponential amplification of a specific DNA segment by cycling through denaturation, primer annealing, and DNA synthesis using a DNA polymerase and primers. In denaturation, the double-stranded DNA melts into single strands. In annealing, short primers bind to complementary sequences flanking the target region. In extension, DNA polymerase extends from the primers, copy­ing the target sequence and creating new DNA strands. Because the newly synthesized DNA contains primers for the next round, each cycle produces more templates for subsequent cycles, leading to exponential amplification of the target region. Primers define the start and end points of the segment being amplified, ensuring specificity. The other descriptions don’t describe this targeted, cycle-based copying process.

PCR relies on exponential amplification of a specific DNA segment by cycling through denaturation, primer annealing, and DNA synthesis using a DNA polymerase and primers. In denaturation, the double-stranded DNA melts into single strands. In annealing, short primers bind to complementary sequences flanking the target region. In extension, DNA polymerase extends from the primers, copy­ing the target sequence and creating new DNA strands. Because the newly synthesized DNA contains primers for the next round, each cycle produces more templates for subsequent cycles, leading to exponential amplification of the target region. Primers define the start and end points of the segment being amplified, ensuring specificity. The other descriptions don’t describe this targeted, cycle-based copying process.