A researcher wants PCR to amplify one specific region of a large genome. Which reaction component provides the sequence specificity that restricts amplification to that region?

Core Concept

Taq polymerase cannot start a chain by itself and extends only from an existing paired 3' end. The two synthetic primers define where the enzyme attaches on opposite strands, so only DNA between the primer sites gets copied. Their base sequence determines which genomic locus amplifies. Redesigning the primers retargets the reaction elsewhere in the genome.