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PCR and DNA Testing

PCR stands for polymerase chain reaction, a critical component of DNA paternity testing. Developed in 1985 by Kary Mullis and others at Cetus Corporation, PCR is a technique used for making millions of copies of short DNA sequences. It takes specific sequences of DNA from very small samples and amplifies them for use in genetic testing. The creation of this technique makes it possible to do DNA paternity testing both quickly and using the painless buccal swabbing sample collection method.

PCR copies specific sequences of DNA through multiple cycles of heating and cooling in a thermocycler (pictured above). But before the heating and cooling begin, the DNA sample is placed in a solution that contains an enzyme called DNA polymerase; free nucleotide bases (the building blocks of DNA); and primers, which are short, specific sequences of DNA in single-stranded form.

Once the solution is prepared, it is heated to about 94ºC, which causes the double-stranded DNA sample to unwind and split into two individual strands. These two strands are the foundations for the new copies of the DNA. When the solution is cooled to 60ºC, the primers bind to the complementary portions of the separated DNA strands. Then, at 72ºC, the enzyme extends the primers by joining the free nucleotide bases to them.

This heating and cooling process is repeated 30-40 times to create millions of copies of the targeted DNA sequence. (Each cycle unwinds the double-stranded DNA molecules in the solution and forms new DNA from the separated pieces.) It takes only hours to produce millions of copies, which are examined in paternity and other family relationship DNA tests

Read more about other technologies used by Prophase Genetics:

Biomek® Robotics Systems

ABI Prism® 3100s