Fridell (2005, p.8) defines Polymerase Chain Reaction (PCR) as a scientific technique that is applied in molecular biology to amplify a single or specified number of DeoxyRiboNucleic acids. In addition, Park (2004, p.587) claims the PCR technique is used to produce a large number of copies of a particular specific DeoxyRiboNucleic Acid sequence. The DNA sequences are utilized in studies that involve DNA cloning, to conduct DeoxyRiboNucleic Acid-based Phylogeny or when there is a need to carry out functional analysis of genes as documented by Pierce and Wangh (2007, p.75). PCR technique finds application in studies concerned with diagnostic of hereditary disease and conducting genetic fingerprint identification which results in gene matching to identify paternity.
This essay provides different reasons that have made the PCR technique a significant invention in molecular biology to date.
Rainbow (1996, p.2) claims Polymerase Chain Reaction (PCR) technique to be the “single most important methodological invention in molecular biology” citing PCR as an applied “routine procedure in molecular biology” (p.4). Fridell (2005, p.88) argues that the PCR technique is applied in the identification and classification of genetic material. Some of the processes whose success depends on PCR technique include cloning, gene sequencing, mutagenesis studies, molecular diagnostic research and genetic analysis (Lawyer et al, 1993, p.23). Khan et al (2008) document that every emerging application of PCR technique has continued to demonstrate competencies in transforming molecular biology.
Ochman et al (1990, pp.623-5) argument claims that the PCR technique has gained wide application in the cloning of genes. The capability to adopt the PCR technique in gene cloning has contributed to the capability to attain a diverse range of genes through mutagenesis and gene recombination which has continued to find application in genetic engineering and the development of drugs through the use of microbes like bacteria. PCR technique has provided foundation for conducting analytical and descriptive studies on functionality of genome. PCR technique has been adapted in mutagenesis studies with aim of identifying gene expression and functional relationships of different protein structure (Rychlik et al, 1990, pp.6410-11). PCR technique has been documented by Pierce and Wangh (2007, pp.66-70) to provide basis for understanding protein-protein interaction, protein engineering and mechanism through which molecular evolution has occured
Khan et al (2008) studies reported that PCR technique is dependent on three cyclical steps namely denaturation phase, annealing phase and extension phase. Denaturation results into conversion of Double helix into a single helix, immediately DNA primers are annealed into complementary single helix DNA. The extension phase of DNA is dependent on support synthetic processes that are dependent on DNA polymerase. The three phases are temperature sensitive and ought to be carried out at specific phase temperature. PCR techniques utilize heat stable DNA polymerase for instance Taq polymerase1 hence themocycling property of the PCR technique. Pierce and Wangh (2007, pp.72-77) claims DNA polymerase has capability to assemble new copies of DNA from its building units. This process involves use of nucleotides for instance a single stranded DNA as template and a DNA primer for instance DNA oligonucleotides. The elements form basis for initiation process for DNA biosynthesis in vivo or in vitro.
Mueller and Wold (1988, pp.780-86) proposed that PCR technique could be used to carry out early diagnosis of malignant tumors for instance leukemia and Lymphomas. This makes it possible to start early cancer management care hence capability to enhance patient quality of life. This reduces hospital length of stay and forms foundation for early home care for cancer patient. In addition, Sharkey et al (1994, pp.506-9) claims PCR technique could be adopted in PCR assay in order to identify translocation specific malignant cell. When conducting PCR assays, PCR technique provides basis for determination of genomic DNA samples. Zietkiewicz et al (1994, pp.176-83) noted that PCR technique could be adopted towards identification of DNA samples that cannot be cultivated hence saving time and costs. PCR can be applied in DNA samples that demonstrate characteristic feature of slow growths. Examples of slow growing micro-organisms include mycobacterium and anaerobic bacteria. This makes PCR an important tool towards diagnostic applications. As a result, it is PCR has made it possible to detect, isolate, identify and classify nature of infectious microbes (Naber, 1994, pp.1508-10). Similarly, Arnheim et al (1990, pp.177-9) claims PCR technique provides backbone for classification of organisms.
According to Mueller and Wold (1988), PCR technique provides basis for early determination of viral DNA post infection. In addition, Naber (1994a, pp.1508-10) studies determined that Viral DNA detection could occur before observation of clinical signs of the disease which provides physician an early strategic management of the disease. This is carried out through determination of viral load through use of PCR-based DNA quantification processes. Other documented application of PCR technique includes capabilities to determine or estimate population size of specified species (Khan et al, 2008; Ochman et al, 1988). PCR has been applied in determination of dispersal of seeds. This forms basis for determination of reproductive efficiencies of plants hence capability to determine natural factors that affect fertility (Arnheim et al, 1990).
Pierce and Wangh (2007, pp.78-81) studies proposed that PCR technique could be used in selective isolation of DNA molecules. The isolation of DNA occurs through selective amplification of specified portions of DNA. This process results into generation of hybridization probes for example Southern hybridization or Northern Hybridization as documented by Fridell (2005, pp.102-109). Lawyer et al (1993, pp.46-9) claims PCR technique finds application in DNA cloning that relies on DNA isolation technology. Isolation of DNA for instance genomic DNA requires larger quantities of DNA. Thus, PCR amplifies DNA which makes it possible to conduct DNA isolation hence providing required support for Northern hybridization, Southern Hybridization and cloning of DNA. PCR technique is therefore important towards amplification and provision of pure forms of DNA that can later be separated by Thin Layer Chromatography. Enhanced solid phase PCR could also be applied in separation of DNA as documented by Korf (1995, p.1502).
Khan et al (2008, pp.392-3) proposed PCR has been applied in determination of DNA sequence of unknown DNA through use of unknown PCR-amplified sequencing. This forms basis for genetic engineering and capabilities to expendite recombinant DNA. This involves insertion of DNA into DNA plasmids hence PCR application in screening of DNA vector. PCR technique based on Korf (1995, pp.1499-50) doesn’t depend on invasive techniques to get samples for DNA typing and amplification. This implies the studies on an organism DNA doesn’t need to disrupt lifestyle of the organism or to seek ethical issues with regard to use of human as subjects of research because PCR technique is independent of behavioral perspectives. Samples for PCR technique could be derived from variant sources for instance urine or faecal matter (Khan et al, 2008, p.391-3).
PCR technique finds application in tiny samples of DNA. This is achieved due to capacity of PCR to contribute into DNA amplification. Fridell (2005) advanced argument that PCR technique works with minute samples for instance feces, scents, hair follicles; skin rubbed on trees or urine samples. This has been applied in forensic analysis and fingerprinting or DNA typing (Sharkey et al, 1993). This has resulted into capacity to utilize trace amounts of samples in order to determine DNA sequence through amplification of the DNA. This means PCR technique is instrumental in forensic analysis via DNA typing and fingerprinting. Other authors for instance Mueller and Wold (1988, pp.780-786) claim that in DNA typing (Cohen, 1995), only small sample of the victim is required from sources like the sweat of the victim extracted from cloths, sputum or saliva. PCR has revolutionized DNA fingerprinting. This has made DNA typing to be employed as strong evidence against a criminal.
Housman (1995, pp.318-20) advanced the argument that PCR technique could be used to determine the number of species that inhabited a given region. This knowledge is vital towards determination of evolutionary process of the organism. Through analysis of DNA sequences of the organisms that inhabited a given area and those that currently occupy the region, it could be possible to determine Genetic revolution that has occurred subject to phenotypic demand for survival.
The capability of PCR technique to be applied in determination of DNA sequence is independent of age of the DNA sample. PCR has been applied successfully in Ancient DNA genetic sequence analysis and determination of DNA sequence of damaged ancient DNA material. This implies PCR has profound application in archeology and evolutionary biology. Korf (1995, pp.1499-1502) claims that PCR has potential to be utilized in correcting errors that have previously been made when carrying out DNA analysis. This makes it possible to correctly classify animals and plants that have become extinct into their own species and families (Markham, 1993). As a result, PCR helps to distinguish species that demonstrate similar physiological relationships yet fall in different families for instance the extinct moas bird of New Zealand that resembled extant New Zealand Kiwi that are different though cannot fly (Arnheim et al, 1990, pp.174-182).
Service (1995, pp.26-7) claims PCR is envisioned to contribute into future capability of decreasing costs of biotechnology research and increasing accessibility to biotechnology and genetic engineering technology into other fields of study. PCR is envisioned to contribute into capabilities to reproduce genetic content and facilitate in genetic analysis of any genetic based material regardless of age hence PCR is envisioned to add value to the archeology through determination of genetic composition, DNA sequence of ancient organisms hence forming an important research tool for genetic evolution studies.
In conclusion, it is clear from evidence from different molecular biology studies and application that that PCR technique represents the most important invention in the history of molecular biology to-date.
References
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Footnotes
- Taq Polymerase is extracted from bacterium Thermus aquaticus