Genetic Testing Dna Test Pcr Analysis

PCR analysis is one of the latest methods for DNA testing. Originating in the 1980s, it’s many times faster, and much less expensive, than earlier processes. Experts across many scientific fields are seeing possibilities for its uses. In addition to speedier results, PCR can provide reliable evaluations on very small, non-invasive tissue samples, even those that are decades or centuries old.

PCR Overview

PCR stands for polymerase chain reaction. “Polymerase” is an enzyme that effectively acts as a “duplicator.” These enzymes exist in every cell. When applied in PCR processing, they create a massive chain reaction, replicating, or amplifying, multiple generations of the original DNA segment, or segments. It’s a very precise process with effectiveness tied to programmed temperature fluctuations and the introduction of what experts refer to as a “cocktail” of ingredients. Each new replication is true to its original single-cell source, thanks to the ability of the enzymes’ oversight.

With the advent and rising popularity of DNA analysis, PCR is truly one of the most important genetic-based breakthroughs in the last few decades. Indeed, molecular biologist Kary Mullis received the Nobel Prize and Japan Prize (both in 1993) for inventing PCR.

The Benefits of PCR

PCR DNA analysis is a great improvement over earlier methods. By comparison, PCR is often complete in minutes or hours, compared to the earliest tests that could take weeks and months. It’s a powerful process and highly beneficial in genetic fingerprinting, paternity cases and much more.

Even better, through a series of careful monitoring and manipulation, it’s possible to alter the process. This can lead to enhanced genetic marker testing for a wider list of hereditary diseases. That means it will be easier to study the variations based on comparisons of normal DNA and molecules taken from carriers or those who have certain diseases.

Scientists are also discovering that PCR is especially useful in detecting certain variants, including cancer and fast-generating illnesses. New bacterial strains can be quickly typed to possibly prevent future epidemics.

How PCR Works

Like many other DNA testing methods, the process is also somewhat complex. It may help to remember that a single DNA molecule is comprised of a “double helix.” Four distinct “nucleotides” exist within these two strands comprising standard groupings. “Adenine” bonds with “thymine,” while “cytosine” bonds with “guanine.” When special enzymes break DNA into fragments, the pairs also group in specific patterns. With enough copies of these patterns, it ‘s possible to render results specific to each individual ‘s genetic markers. That’s an extremely simplified version of how DNA analysis begins.

In PCR testing, the double helix is heated to make the two strands break apart. Each is then paired with a “primer.” This primer is a single DNA strand complementing the structure of each base strand. Through a heating and cooling process, the two new strands bind together, which is known as “annealing.”

From here, the duplication process begins. The first strands, or templates, produce two new strands; the two new pieces then replicate as a third generation. The process continues until literally millions of DNA replications result from a single molecule. This is what makes PCR such an exciting tool in the scientific field. In the past, analysis required an original base of thousands of DNA molecules to be effective. With PCR, it ‘s possible to take smaller samples from almost any subject or site, including archeological digs or ancient human tissue.

Real-Time PCR

As new advances continue, “traditional” PCR has given way to “real-time” PCR. In a test-tube environment, immediate analysis can determine whether the DNA is viable from a single source. A single hair or a minute trace of blood is all that’s needed. In the traditional method, PCR undergoes a “gel electrophoresis.” This is similar to the process used in RFLP (restriction fragment length polymorphism), in which the fragments are electrified and then X-rayed. Currently, a heating unit about the size of a small microwave oven provides the temperature-controlled environment.

Contamination is one of the drawbacks of this method, however. It’s very easy to collect the wrong material or select samples from multiple sources. Under analysis PCR replication that is contaminated or degraded beyond use can lead to erroneous implications. Careful controls at the collection site and in the testing labs reduce or eliminate this issue.

Predictions and actual advancements in PCR are on a rapid increase. It may soon be possible to test on-site with almost instant results. Devices will continue to be miniaturized and researchers will strive to find ways to apply PCR in every environment from artifacts to plants and humans.

Resources (n.d.). The Polymerase Chain Reaction (PCR). Retrieved September 5, 2008, from the Rutgers University Department of Genetics, Department of Molecular Biology and Biochemistry, Division of Biological Sciences and the Waksman Institute Web site: (2007). DNA Testing Methods. Retrieved September 5, 2008, from the U.S. Department of Justice Web site: (n.d.). PCR and Thermocycler Basics. Retrieved September 5, 2008, from the Ward ‘s Natural Science Teacher Resources Web site: