Polymerase Chain Reaction (PCR)
Start with the big picture
PCR uses template DNA, two primers, a heat-stable DNA polymerase, dNTPs, magnesium ions, and buffer. Each cycle separates the DNA strands, allows primers to bind their target regions, and extends those primers to make new DNA. Repeating the cycle produces theoretical exponential amplification. Primer sequence and reaction conditions affect which regions are amplified, while polymerase choice influences copying fidelity. The topic also introduces variants such as RT-PCR, qPCR, multiplex, touchdown, nested, and hot-start PCR, each with a distinct approach or purpose. Applications include pathogen detection, mutation analysis, forensic DNA typing, and cloning. Because contamination can compromise results, careful laboratory practice matters; agarose gel electrophoresis can be used to check whether the product has the expected fragment size.
What you'll learn
- Identify the essential components required for PCR.
- Describe the three stages of a PCR cycle.
- Explain how primer design and magnesium ions affect amplification.
- Distinguish common PCR variants by their approaches.
- Recognize contamination-control practices and product verification methods.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
