Essay What is the Polymerase Chain Reaction (PCR)
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The polymerase chain reaction or PCR for short can be used to create many copies of DNA. This allows the DNA to then be visualized using a dye like ethidium bromide after gel electrophoresis. The process has been refined over the years, however the basic steps are similar.
The first is to denature dsDNA through heating to ~96 °C. This separates the two strands of DNA. The exact temperature to be used can be calculated with Tm = 4oC x (no. of G & C) + 2oC x (no. of A & T). Tm is the melting point of the strands and to supply the number of G, C, A, & T ‘s the primer is used.
Annealing of primers is then possible when the temperature cools down to 37-65 °C.
Extension from these primers can be done through the use of heat stable (has to…show more content…
However it is a known carcinogen and therefore alternatives have been developed. These, for instance gelred, can be used without the use of UV lighting. However they are often a lot more expensive.
A general issue is that PCR techniques can be very sensitive; any contamination can be amplified. This in combination with the improvements in technique seen over the last few years can mean that for instance in forensics, extensive care needs to be taken when handling samples to prevent contamination. The interpretation of results can also prove tricky for levels of contamination (or DNA that was there due to circumstances unrelated to the crime) that may not have been noticeable with earlier techniques can point the blame to someone who was in fact innocent.
However forensics is not the only area that has been advanced by PCR techniques. Diseases diagnosis can be made much more accurately and quickly. The diagnosis however is not just limited to infectious diseases caused by bacteria, tumours can also be analysed. Therefore it may become apparent if it is the result of a general genetic abnormality or simply an untimely mutation. Viruses similarly can be detected if someone is infected, along with the viral load; this allows disease progression to be monitored.
Genetic mutations are important for tracking disease abnormalities and if there are any causal links between unsuspecting genes and diseases. Not
Polymerase Chain Reaction Essay
1003 Words5 Pages
One may view cloning as copying a living thing and producing multiple copies. People may think of cloning rabbits, sheep or humans. In the field of molecular biology, however cloning is viewed at a genetic molecular level, where a piece of DNA is copied on a large-scale by genetically copying tens to hundreds of thousands of identical DNA fragments. Researchers are developing new methods of cloning by using polymerase chain reaction (PCR). PCR was introduced in the 1980s and in recent years Kary Mullis won the Nobel Prize in Chemistry for his invention of PCR. Today, Scientists today are researching the various sub-fields of cloning, using PCR, in new ways using terminators, enzyme insertion, and types of cloning to produce high…show more content…
This article also explain how polymerase chain reaction (PCR) is the most powerful amplification technology available for producing large quantities of DNA from a sample (Mullis et al. 2006). The scientists also tested thermo stable DNA polymerase and found Thermus aquaticus Polymerase (Taq) is the best for polymerase chain reaction. PCR is composes of three steps; denaturation, primer annealing, and polymerization. In the denaturation step, the target DNA is separated into two stands through heating, the hydrogen bonds between complementary bases, yielding single stands of DNA. In the annealing step, the temperature is decreased to anneal the primers. In the polymerization step, the template DNA is used by Taq polymerase to produce a complementary copy by extending the primers from their 3’ ends of the DNA. The development of thermo stable polymerases based on Taq, T4 DNA, and pfu polymerase, revolutionized PCR and converted it to a technique that can be used routinely in any lab.
In respect to molecular biology, cloning has been the center for branching out new technologies in the topic to cloning. In Cloning and analysis of PCR-generated DNA fragments (Coasta et al. 1994), had explored the five main methods for cloning. They include, restriction enzyme site incorporation, T/A cloning, Uracil-DNA-gylcosylase cloning (UDG), ligase independent cloning, and blunt ended cloning.
Each of the five many cloning