PCR stands for "Polymerase Chain Reaction" which is a biochemical process used to amplify target DNA sequences. Since its invention in 1983, PCR has become a bedrock technology in molecular biology and biomedical science. DNA consists of two strands of nucleic acid units bound together by pairs of matching bases. When DNA is heated to a temperature (approximately 90°C), the two strands come apart, exposing the bases (these are known as the parent strands). Through cooling and heating at specific temperatures in repeating cycles, the exposed bases on both strands will be matched to new bases, creating new strands that are complementary to the parent strand. Done over and over, this process will exponentially increase the number of DNA copies that are present.
PCR like a targeted copy machine for DNA or RNA. If there’s just one copy of the target DNA or RNA in your sample, the PCR process makes billions of copies, which can then be detected. PCR offers superior accuracy, speed, and ease-of-use when compared to other detection methods, like standard culture methods.
EXAMPLE:
| # of Cycles | 1 | 2 | 4 | 10 | 20 | 30 | 35 | 40 |
| # of DNA Strands | 2 | 4 | 16 | 1,024 | 1,048,576 | 1,073,741,824 | 3.43 x 10^10 | 1.09 x 10^12 |
Applications of a PCR machine are truly infinite. Some common uses are for diagnostic testing and quantitation (viral or bacterial), forensics (amplifying DNA from an extremely small blood sample to use for analysis), DNA-sequencing, cloning, etc.
Real-time PCR is an updated PCR method that allows results to be available as the reaction proceeds. Instead of waiting for the entire reaction of over 25 cycles to finish, you can watch the reaction proceed in “real-time”. Biomeme's Franklin Thermocycler provides both “quantitative” results through qPCR amplification graphs and qualitative results.