PCR method: basics

In short: The polymerase chain reaction (PCR) is a laboratory method used to multiply the smallest amounts of DNA millions of times over. It forms the basis for numerous applications in medicine, forensics, and research.

In more detail: The method uses the natural principle of DNA duplication, which also occurs during cell division, and artificially replicates it in the laboratory.

In detail

• Denaturation: Heating to about 95 degrees separates the two DNA strands so they exist individually.
• Primer binding: On cooling, short, specific DNA fragments called primers attach to the target sequence, marking the starting point for amplification.
• Elongation: A heat-stable enzyme called DNA polymerase extends the primers, building new, complementary DNA strands.
• Cyclic repetition: These three steps are repeated 20 to 40 times, exponentially multiplying the amount of target sequence.
• Thermocyclers: Specialised devices automatically control the precise temperature changes needed for the individual PCR steps.
• Diagnostic application: PCR tests are used to detect the genetic material of pathogens like viruses or bacteria with high sensitivity.
• Other applications: The method is also used in paternity testing, forensic trace analysis, and basic research (dna-und-rna-unterschiede, proteinbiosynthese-einfach-erklaert).