*Polymerase Chain Reaction DOI: http://dx.doi.org/10.5772/intechopen.81924*

*Genetic Engineering - A Glimpse of Techniques and Applications*

community members

population genetics

and new species

proteins

Site-directed mutagenesis

Personalized medicine

Forensics sciences

Gene expression profiling

Identifying medicinal plants

**Table 2.**

**Application Description Reference**

PCR-based approaches are commonly used to insert mutations (deletions, additions, and substitutions) at specific locations in a gene to study role of specific amino acids in the structure and function of

PCR technologies are employed in pharmacogenomics and

samples from crime scenes and make them reliably analyzable.

the polymorphic nature of DNA (SNPs, DNA repeats, etc.) to study the structure and diversity ecological communities, phylogeny, and

Reverse-transcriptase PCR and qPCR are routinely employed to profile the expression of genes and to validate transcriptome profiles generated

genetically modified organism in food and feed to ensure their regulation

PCR-based DNA barcoding is a tool that utilizes specific DNA sequences to rapidly and accurately identify medicinal plants species from other morphologically similar plants. This approach is also used by ecologists and conservation biologists to identifying endangered

identify rarest members of a sampled community and rare genes in the

pharmacogenetics to track genetic markers that determine the response of individuals to treatments and are used to design tailor-made drugs and

The power of PCR is employed to amplify poor quality and quantity DNA

[85, 86]

[87, 88]

[74, 89]

[67, 68, 90]

[90]

[91–93]

[94]

[95, 96]

[97–99]

Metagenomics Gene-targeted metagenomics combines PCR with metagenomics to

to prescribe drugs in effective doses

DNA profiling DNA profiling methods utilize PCR-based approaches to exploit

through techniques like microarray and RNA-seq

Detecting GMO PCR techniques are used to quickly and reliably track the presence of

Meat traceability PCR methods are used to identifying and quantifying adulteration of

and protection of consumer rights

meat in raw and processed food.

the scientific research and diagnostic medicine. Over the years, it has become a vital of clinical and diagnostic research. It has a wide range of applications in almost every field of science, for example, clinicians widely use the technique for disease diagnosis. Biologists, including agriculturists, clone and sequence genes using PCR and rapidly carry out sophisticated quantitative and genomic studies. Now for criminal identification, PCR assays are commonly employed. DNA fingerprinting is also used in paternity testing, where the DNA from an individual is matched with that of his possible children, siblings, or parents [67, 68]. Besides, PCR has enormous role in diagnosing genetic disease, whether inherited genetic changes or as a result of spontaneous genetic mutations, is becoming more common. Diseases can be diagnosed even before birth. Even PCR can also be employed with significant precision to predict cure of diseases

[73]. The most important applications of PCR are summarized in **Table 2**.

Since it discovery in 1980s, the PCR technique has brought about significant changes in biological sciences. Huge scientific undertakings like the Human Genome Project have been possible due to PCR-based approaches [5, 6]. It is a very sensitive

**24**

**10. Limitations of PCR**

*The most important applications of PCR.*

and flexible technique to amplify DNA of interest. A very small amount of the target DNA can be used as a starting material. Even old or degraded DNA samples may yield successful amplification. However, there is also a long list of PCR limitations. High-quality DNA amplification needs information about target DNA sequence. The sensitivity of PCR is also its major disadvantage since the very end result of a PCR is highly susceptible to contamination or false amplification. Therefore, amplification of DNA by PCR may not be 100% specific. Moreover, the specificity of amplification is dependent on physicochemical parameter, such as temperature and Mg++ concentration. The PCR is also inhibited by the presence of certain chemicals such as ethanol, phenol, isopropanol, detergent compounds like sodium dodecyl sulfate (SDS), high salt concentration, chelators, etc. There is an upper limit to the size of DNA that can be synthesized by PCR. Additionally, analysis and product detection usually take much longer time than the PCR reaction itself.
