What Is The Polymerase Chain Reaction (Pcr)

1230 words - 5 pages

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 be able to withstand the denaturing process) DNA polymerase. Taq polymerase is often used for this.

The process is repeated for many cycles to create more copies. This occurs in theory at 2n rate, with n = number of cycles. This process is done in a thermal cycler, which can be set at different temperatures dependent on the organism used.

The choice of primer to select the genes of interest should at least be 18 nucleotides long, so they should be unique in the genome. Also they should work at a similar annealing temperature and be dissimilar (or they’ll anneal to each other).

The final step must be visualisation however. A DNA ladder is a set of DNA fragments with known molecular weights. This runs alongside the PCR process. When used on the gel, it then provides a comparison to determine the molecular weight of the target sequence after they have been run on an agarose gel. If possible a positive and negative control should be used. The first to see the PCR reaction actually worked, and secondly to exclude contamination of the reagents to rule out false positive results. Ethidium bromide can be used in combination with UV lighting to visualise the bands. 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...

Find Another Essay On What is the Polymerase Chain Reaction (PCR)

EVALUATION OF MULTIPLEX POLYMERASE CHAIN REACTION USING TWO PRIMERS AND ITS COMPARISON WITH CONVENTIONAL ISOLATION TECHNIQUES FOR THE DIAGNOSIS OF

602 words - 3 pages ´ and 5´-GTC CTC GCG AGT CTA GGC CA-3´respectively.11 The PCR assay contained 10pM of each primer, 10mM dNTPs, 10x buffer, 2.5 units of Taq polymerase and 5μl of extracted DNA. PCR tubes were subjected to 95˚C for 5 minutes and 35 cycles each of denaturation at 95˚C for 1 minute, annealing of primers at 68˚C for 1.5 minutes, primer extension at 72˚C and final extension at 72˚C for 10 minutes. Test results were compared with the results for one

What is Supply Chain Management? Essay

732 words - 3 pages . These organizations are referred to collectively as the supply chain. Rare productions understood, much less managed, the entire chain of activities that ultimately delivered products to the ending buyer. The effect was disorderly and often unproductive supply chains. The added indication is that while supply chains have happened for a long time, most formations have only paid attention to what was happening within their “four walls.” Supply

What is Supply Chain Management?

1478 words - 6 pages in supply chain management and its future prospects. RFID Technology: Identifying any object using radio frequency is termed as RFID. The major advantage of RFID over barcodes is that using RFID items can be scanned even if they are not in line of sight and that too without manual support. [4] RFID network consists of three major components: RFID tag or transponder, Antenna or receiver and reader. • RFID Tag or transponder: A RFID tag or a

What is a Commodity Chain

1734 words - 7 pages With the industrial revolution came a new era of trading goods and a redefined global market. It became easier and easier to form a network of interdependence between nations, and more importantly, cheaper to buy a pair of jeans. Using our connectedness, we are now exporting labor thousands of miles over seas, and reaping the benefits of these commodity chains. A commodity chain is the process in which resources needed are gathered, and

Write the summary, reaction and what you believe is the expansionist response to Roxanna Robertson's article- "Watching As The World Vanishes"

1005 words - 4 pages make it all go away.But, the thing is, that, if the humans continue with the consumption at this pace, by the end of this century one half of the species may be extinct. The current rate of extinctions is at least 1000 times higher that the natural level. What people need to understand is that these species are important to us. They are important to us because they provide us with oxygen, food, medicine; all of these species have a special purpose

"What is Democracy" This is an essay written about democracy. It a reaction of an average person as to what democracy means to them. This is not a step by step definition of the political system

1354 words - 5 pages ironies of these facts is that most citizens of democratic countries do not know what the word democracy means and what it represents. "A citizen of America will cross the ocean to fight for democracy, but wont cross the street to vote in a national election." Bill VaughanThe Oxford dictionary defines democracy as government by the people, direct or representative. In Canada we have a representative democracy that allows us to pick our political

What is the Internet?

559 words - 2 pages . The Internet itself does not contain information. It is a slight misstatement to say a "document was found on the Internet." It would be more correct to say it was found through or using the Internet. What it was found in (or on) is one of the computers linked to the Internet.Computers on the Internet may use one or all of the following Internet services:* Electronic mail (e-mail). Permits you to send and receive mail. Provides access to

What is the Truth?

1764 words - 8 pages Before I begin to pen ink on paper I want to ask you a question. “What is the truth?” I like any prolific author am trying to be concise about my whole contexts. Before long it suffices me to say you will know enough and be equipped well enough to understand the discontinuity of these passages. I want to make it clear that before your journey reaches its end you will come across many liars. Many books, characters, its plot holes and all its

What is the Gospel?

1389 words - 6 pages In the world, there exist 129,864,880 books. The chances of someone reading every single book is virtually impossible. One of these books holds information, beliefs, and truths that are pinnacle to Christianity. This is, of course, the Bible. In the Bible, namely the New Testament, there are many letters. Paul, who wrote many of these letters, proclaims the gospel, the “good news”. What is this good news and what are the so-called “gospels

What is the self?

790 words - 4 pages What is personal identity? Surely most people have some rough idea of what it is, but there is more to it than what people think. So often people in life assume for the sake of assuming not aware of how little they actually know. On the topic of person identity there were two great philosophers David Hume, and John Locke both of whom held very different views on the topic, but they both show just how deep this topic can be. Hume's "Of personal

What is the Cost?

1977 words - 8 pages What is the Cost? Everyone dreams to achieve something in life. Many people strive to be a better parent, better athlete, or just a better person all around. How do they achieve this though? Do they work harder, spend more time with one another, or strive for more money and nicer items? Some say this could be the American Dream, have a good job, family, and money to buy whatever they may wish, but what is the real cost of the American Dream

Similar Essays

Polymerase Chain Reaction (Pcr) Essay

3001 words - 12 pages molecule has become hundreds of thousands of molecules.When Dr. Mullis developed polymerase chain reaction, he thought of it as a concept and his words highlight the importance of his concept even today. For him, the thing about PCR wasn't just "putting those things together, the remarkable part is that you will pull out a little piece of DNA from its context and that's what you will get amplified. That was the thing that said 'you could use this to

Polymerase Chain Reaction Essay

1016 words - 4 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

Evaluation Of Multiplex Polymerase Chain Reaction Using Two Primers And Its Comparison With Conventional Isolation Techniques For The Diagnosis Of

798 words - 4 pages A total of 55 subjects were grouped into ‘confirmed’ TBM (n=9)’ and ‘suspected’ TBM (n=46) categories. The 60 control subjects included patients who presented with bacterial, viral, fungal or non infectious cause of CNS symptoms. The results of AFB smear, LJ and BACTEC culture and different PCR methods between cases and controls were compared (Table 3). Figure 1 shows the gel photograph of multiplex PCR (multiplex PCR is considered as positive

Evaluation Of Multiplex Polymerase Chain Reaction Using Two Primers And Its Comparison With Conventional Isolation Techniques For The Diagnosis Of

1036 words - 5 pages BACTEC have not only poor sensitivity but they also take longer time to give positive results making these tests less useful to the clinician in the diagnosis of TBM. Nucleic acid amplification tests (NAATs) have been found to be most sensitive and specific method among the available diagnostic techniques. In the literature, wide variability is seen with regard to the sensitivity of PCR. The reported sensitivity of the PCR technique in CSF varies