Biotechnology - MCQ Practice Questions

Inverse PCR amplifies unknown DNA sequences flanking a known region by using outward-facing primers on a circularized DNA template, useful for genome walking and transposon mapping.

ddPCR partitions samples into independent reactions, allowing Poisson distribution analysis for absolute quantification without reference standards.

NGS and allele-specific digital PCR can detect rare mutations (ctDNA) with high sensitivity; RFLP/DGGE are less sensitive for point mutation detection.

Universal primers (e.g., 16S rRNA) must accommodate sequence variations across taxa while maintaining specificity, creating a design dilemma.

Long-range PCR requires thermostable polymerases with 3'→5' exonuclease activity (e.g., Pfu, Phusion) and extended elongation times for processivity.

Allele-specific qPCR can rapidly detect known resistance mutations (e.g., rpoB in rifampicin resistance) in clinical TB samples for faster diagnosis.

GC-rich regions form hairpins; additives (DMSO/betaine) destabilize secondary structures, while higher denaturation temperatures and specialized polymerases enhance amplification.

Digital PCR partitions samples into thousands of individual reactions, enabling absolute quantification without standard curves. This is crucial for detecting rare mutations where ctDNA comprises only 0.01-1% of total circulating DNA, making it superior for cancer diagnostics.