Question

What are the drawbacks of the PCR?

Answer 1

The technique was discovered by Dr. Kary Mullis in 1983. It stands for polymerase chain reaction used for amplification and detection of specific sequences of DNA using fluorescent DNA binding dye, laying the foundation for future "real time'' or kinetic PCR.

Complete answer:
To answer this question you must know about PCR technique.
PCR stands for polymerase chain reaction, a molecular biochemical technology in which single molecules of the genetic material DNA get converted into 100 billions similar molecules within some time. In this technique we used heat -stable DNA polymerase which synthesized the new strand of DNA.
The PCR technique is a rapid technique that does the specific amplification and it is very sensitive as well. The most important is the closed system so it reduces the risk of contamination. Still there are certain drawbacks of PCR technique such as:
1. It has potentially lower specificity compared to culture and staining. trained people are required to perform these techniques.
2. It needs a narrow list of causative agents to use specific primers and there are a maximum of four reactions occurring simultaneously.
3. Variation increases with cycle number and product of PCR increases exponentially without monitoring amplicon size.
4. Increased risk of false negative results in pathogen detection particularly for new emerging or highly variable pathogens.
5. It becomes less cost effective when performed with a multi- organisms of PCR approach and it is expensive as well due to supply cost, machinery fees and training expenses.

Note:
This invention allowed scientists to amplify a single targeted strand of DNA. It is one of the most widely used laboratory methods for detecting the COVID -19 virus. Many countries used this technique to diagnose the Ebola virus, zika virus etc., many need support in adapting this method for COVID -19 virus, as well as in increasing their national testing capacities.