In TaqMan PCR, the is different from ordinary PCR.
a. DNA template
b. Primers
c. Nucleotides
d. Probe
The correct answer and explanation is:
The correct answer is d. Probe.
In TaqMan PCR, the key difference from ordinary PCR lies in the use of a probe in addition to the standard primers. In a typical PCR reaction, the amplification process is tracked by monitoring the increase in the DNA product over successive cycles. However, TaqMan PCR employs a more specific method of detection using a fluorescently labeled probe.
Here’s how it works: The TaqMan probe is a short, single-stranded DNA sequence that is complementary to a region of the DNA target between the two primers. The probe is labeled with a fluorescent reporter dye at one end and a quencher dye at the other. During PCR amplification, the DNA polymerase (usually Taq polymerase) moves along the template strand, extending the primers. As the polymerase encounters the TaqMan probe, it cleaves the probe, separating the reporter and quencher dyes. This separation causes the reporter dye to emit fluorescence, which can be detected in real time. The increase in fluorescence intensity is directly proportional to the amount of PCR product being produced, allowing for precise quantification of the DNA target.
In contrast, traditional PCR does not use a probe. It typically relies on gel electrophoresis or other post-PCR methods to analyze the amplification product. The TaqMan system is more sensitive and specific, allowing for real-time PCR to quantify DNA while the reaction is occurring, making it highly suitable for applications like gene expression analysis, pathogen detection, and genotyping.