1. Polymerase Chain Reactions
Revised May 2010

2. What is PCR?
Technique which takes a small DNA sequence and makes it usable for further testing
Faster way of cloning specific DNA
Developed in the 1980s by Kary Mullis, who won a Nobel Prize for her research
PCR targets segments at the end of each sequence it wants to amplify
Number of targets can vary

3. Primers
Primers are strands of DNA 15 to 30 nucleotides long used as the complimentary building blocks of the target sequence
Primers for each target sequence is needed for DNA to be copied properly
Primers should be added in excess to prevent DNA strands from binding back on each other

4. Taq Polymerase
Produces an enzyme called DNA polymerase which, in the presence of magnesium, amplifies the DNA between the primers
Named for the Thermus aquaticus microbe found in Yellowstone National Park

5. PCR Process Denaturation Annealing Elongation of the strand at 72o
Separate DNA strands by heating them to 95o
Annealing
Allowing DNA to form hydrogen bonds by cooling to 55o
Elongation of the strand at 72o
There are many cycles in the process, usually between 25 and 40.
Takes place in a thermal cooler

6. Why Use PCR?
Diagnose Chlamydia trachomatis and Neisseria gonorrhea, two sexually transmitted diseases
Part of the HIV-1 test to check the severity of the disease
Test for mutations in Factor V Leiden, which can cause blood clots
Forensic testing