#Id: 2536

#Unit 13. Methods in Biology

At the second cycle of PCR, primers will anneal to the 'long product' at sites where sequences complementary· to them are located, which will be much before the actual 3'-end of the long product.

#Id: 2537

#Unit 13. Methods in Biology

Extension step in the second cycle will produce a product that will be much shorter than the 'long product'; this is the 'correct' PCR product and represents the target sequence

#Id: 2538

#Unit 13. Methods in Biology

The original template sequence will also be copied during the second and all subsequent cycles to generate the 'long product'. Therefore, the long product continues to increase linearly, while the 'correct PCR' product will multiply exponentially. 

#Id: 2539

#Unit 13. Methods in Biology

In PCR, the length of primers is of great importance in ensuring that only the target sequence is amplified. 

#Id: 2540

#Unit 13. Methods in Biology

In PCR, the primer length influences the rate at which primer molecules pair with template DNA; this rate decreases as the primer length increases.

#Id: 2541

#Unit 13. Methods in Biology

The PCR primers must not have self complementary regions as this would lead to hairpin formation within primer molecules and make then unsuitable for PCR.