- PCR is very sensitive – any impurities in the DNA sample can cause errors in the results. 

- Although the PCR primers are designed to be specific to the DNA fragment of interest, they can anneal to pieces of DNA which will cause the PCR to amplify wrong pieces of DNA. Thus, great care must be taken to not contaminate the samples.  


Grand Valley State University

Polymerase chain reaction (PCR) was discovered in 1985. It is technique usedin laboratories that allows for the synthesis of a lot of a specific fragment of DNA 

Polyermase Chain Reaction (PCR)

Garibyan, L., & Avashia, N. (2013). Polymerase chain reaction. The Journal of investigative dermatology, 133(3), 1–4. 

Polymerase Chain Reaction

PCR has been used to diagnose diseases, identify a perpetrator in a crime scene by matching the DNA at a crime scene with suspects, clone genes, and sequence genes. 

Applications of PCR

Disadvantages of PCR

There are three broad steps of PCR
- Denaturation 
- Annealing
- Extension 

These steps are repeated as many times as desired to keep synthesizing the DNA fragment desired. 

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