PCR is considered to be a very sensitive technique because it can detect trace amounts of DNA in a sample. Which of the following aspects of PCR generates this sensitivity?

Question

The high fidelity of the DNA polymerase
The numerous rounds of melting, annealing, and extension
The proper use of control DNA
The thermostability of the DNA polymerase
The use of RNA primers

Suppose that you worked in a laboratory designing a PCR test to detect the presence of West Nile Virus in a patient's sample. Your supervisor says that you need to include a control that verifies that the reactions have not been contaminated with DNA from the environment or from another sample. Which of the following would best serve to test for contamination?
A reaction that contains all of the reaction components except template DNA
A reaction that contains DNA of the West Nile VIrus
A reaction that contains extra enzyme
A reaction that contains primers that are specific for human DNA
A reaction that contains the patient's DNA

Answer 1

1. The aspect of PCR that generates its sensitivity is the numerous rounds of melting, annealing, and extension. This is because PCR amplifies a specific target DNA sequence exponentially through repeated cycles, allowing for the detection of very small amounts of starting material.

2. To test for contamination in the PCR reactions when designing a test for West Nile Virus, the best control would be a reaction that contains all of the reaction components except template DNA. This negative control allows you to verify that no contamination has occurred, as any amplification in this control would indicate contamination in the reagents or environment.