Practice question

Primer concentration critically influences PCR success and background formation. Working range of 0.1 to 1.0 micromolar, most commonly 0.2-0.5 micromolar, provides sufficient oligonucleotide to efficiently anneal to template during each cycle without driving non-specific annealing or primer-dimer formation. Excessively high concentrations ranging from 10 micromolar to millimolar sequester magnesium ions, promote mispriming, dimerization, and smeared gels, while inhibiting polymerase processivity. Too low concentration exhausts early and reduces final amplicon yield. Optimized concentration maintains exponential amplification and is standard in NCERT and molecular biology laboratory protocols.