Question 1 of 9 Fundamentals Concept
What does a no-template control tell you in PCR?
Short answer
A no-template control tests whether your PCR reaction produces signal without intentionally added target material. A positive signal suggests contamination, primer-dimer formation or another unwanted amplification process. It does not by itself reveal which explanation is correct.
Why
PCR amplifies nucleic acid so effectively that tiny contamination can mimic a real positive. An NTC contains the PCR reagents and water or other appropriate substitute instead of the sample template. It helps detect contamination introduced through reagents, pipetting or carryover.
In dye-based qPCR, primer-dimers can also generate fluorescent signal. Inspect when the NTC amplifies, compare its amplification and melting curves with true samples, and assess the chemistry used. Controls should be repeated and investigated when positive.
A no-RT control answers a different question for RNA work: whether DNA remained in the RNA preparation. A clean NTC supports confidence in the run, but does not prove that the intended product is specific or that sample extraction was free from cross-contamination.
A strong answer covers
- Identify what the control can and cannot establish