* Specificity: Each primer is designed to bind to a specific sequence on opposite strands of the DNA molecule. This ensures that only the desired target region is copied.
* Directionality: The two primers are complementary to opposite strands of the DNA and bind in opposite directions. This is crucial because DNA polymerase, the enzyme responsible for DNA replication, can only extend a DNA strand in one direction.
* Creating a defined region: The region between the two primers becomes the template for DNA synthesis. The polymerase starts copying from the 3' end of each primer, moving towards each other. This results in the amplification of the DNA fragment located between the two primers.
In short: The two primers act as "bookends" for the target DNA sequence, ensuring that only the desired region is amplified. This makes PCR a highly specific and versatile technique for identifying and studying particular DNA sequences.
