Final answer:
Nested PCR uses two successive rounds of PCR with two different sets of primers to amplify a specific DNA region with high specificity, while multiplex PCR amplifies multiple targets in one PCR reaction using multiple primer sets. QuickChange PCR is used for site-directed mutagenesis, not for amplifying DNA.
Step-by-step explanation:
Nested PCR and multiplex PCR are variations of the polymerase chain reaction (PCR), which is a common method in molecular biology to amplify DNA. Nested PCR involves two sets of primers used in two successive runs of PCR to increase specificity of the amplified product. The first set of primers amplifies a target sequence, and the second set, which binds within the first PCR product, amplifies a smaller region within that target. This increases the specificity and sensitivity of the PCR. In contrast, multiplex PCR allows for the simultaneous amplification of multiple targets in a single PCR reaction by using more than one pair of primers. This is particularly useful when analyzing samples with limited amounts of DNA.
QuickChange PCR, mentioned in the context provided, is a site-directed mutagenesis technique that allows for the introduction of mutations at specific sites within a DNA sequence. It uses primers that contain the desired mutation and does not emphasize amplification like standard PCR; rather, it prioritizes introducing specific base changes into a DNA sequence. Consequently, QuickChange PCR yields less amplification compared to standard PCR but is ideal for introducing precise mutations.