What is the basic purpose of polymerase chain reaction (PCR) in molecular biology?

What is the basic purpose of polymerase chain reaction (PCR) in molecular biology?

• A. Sequence entire genome
• B. Polymerase chain reaction amplifies a specific DNA sequence for analysis or testing.
• C. Denature proteins
• D. Transcribe RNA into DNA

Answer: (B)

PCR's basic purpose is to amplify a specific DNA sequence so it can be analyzed or tested. It uses short DNA primers that flank the target region, a DNA polymerase that builds new DNA, nucleotides, and repeated temperature cycles. In each cycle, the DNA is heated to separate the strands, cooled so the primers can bind, and then extended by the polymerase to copy the target region. After many cycles, the amount of that particular DNA fragment grows exponentially, making it easy to detect or study even very small samples.

This isn’t about sequencing an entire genome—PCR targets a defined segment rather than trying to copy every part of the genome. It doesn’t denature or modify proteins. And while there is a technique that converts RNA into DNA before amplification (RT-PCR), standard PCR itself is about amplifying DNA, not transcribing RNA.