True about PCR is
**Core Concept**
Polymerase Chain Reaction (PCR) is a molecular biology technique used for amplifying specific DNA sequences. It involves the use of heat-stable DNA polymerase, primers, and nucleotides to generate millions of copies of the target DNA sequence.
**Why the Correct Answer is Right**
The correct answer is based on the principle of PCR, which relies on the ability of DNA polymerase to synthesize new DNA strands by adding nucleotides to a template strand. The reaction involves three main steps: denaturation, annealing, and extension. In the denaturation step, the double-stranded DNA is heated to separate the strands. In the annealing step, the primers bind to the target DNA sequence. In the extension step, the DNA polymerase synthesizes new DNA strands by adding nucleotides to the primers. This process is repeated multiple times, resulting in exponential amplification of the target DNA sequence.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because PCR is not a technique used for sequencing DNA, but rather for amplifying specific DNA sequences.
**Option B:** This option is incorrect because PCR does not involve the use of restriction enzymes to cleave DNA, but rather the use of primers and DNA polymerase to amplify DNA.
**Option C:** This option is incorrect because PCR is not a technique used for DNA cloning, but rather for amplifying specific DNA sequences.
**Clinical Pearl / High-Yield Fact**
One key feature of PCR is its ability to amplify specific DNA sequences with high specificity, making it a powerful tool for diagnosing genetic disorders and detecting infectious agents.
**Correct Answer:** D.