True about polymerase chain reaction (PCR) –
**Core Concept**
Polymerase chain reaction (PCR) is a laboratory technique used for amplifying specific DNA sequences in vitro. It relies on the thermal stability of DNA polymerase enzymes and the principle of exponential DNA replication.
**Why the Correct Answer is Right**
The PCR process involves denaturation of the target DNA at high temperatures, annealing of primers to the complementary DNA sequences, and extension of the primers by the DNA polymerase enzyme. This cycle of denaturation, annealing, and extension is repeated multiple times to exponentially amplify the target DNA sequence. The Taq polymerase enzyme, a thermostable DNA polymerase, is commonly used in PCR reactions due to its ability to withstand high temperatures.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because PCR is not primarily used for sequencing DNA. While PCR can be used to generate DNA templates for sequencing, it is not the primary purpose of the technique.
**Option B:** This option is incorrect because PCR is not a technique used for DNA repair. PCR is designed to amplify specific DNA sequences, not to repair damaged DNA.
**Option C:** This option is incorrect because PCR is not a technique used for protein synthesis. PCR is a DNA-based technique, not a protein-based technique.
**Clinical Pearl / High-Yield Fact**
A key consideration in PCR is the primer specificity, which is critical for amplifying the correct target DNA sequence. Non-specific primers can lead to amplification of non-target DNA sequences, resulting in false-positive results.
**Correct Answer: C. PCR is a technique used for amplifying specific DNA sequences in vitro.**