What is DNA?
"DNA is called 'blue print of life'."
DNA is large complex protein that carries the genetic information or genetic "code" of an organism. It is made of two parallel strands of protein arranged in a helix, like a spiral staircase. The two twisting strands of protein are referrered to as a 'double helix'. DNA is often called the "blue print of life" because it carries the "instructions" on how to build every part of a specific organism. All common forms of life, such as viruses, bacteria, plants, and animals carry a copy of their own genetic code in each of their cells. Organisms that are closely related genetically have very similar DNA patterns, which organisms that are quite different share little DNA in common. For example, the DNA of a cat is very similar to that of a lion, but it is quite different from the DNA of the dog or horse. However, regardless of how similar two organisms might be, there are differences in their DNA that makes each organism unique.
What is the DNA-PCR test?
The letters PCR stand for polymerase chain reaction. The word 'polymerase' refers to DNA-polymerase, which is an enzyme that plays an essential role in building DNA. The DNA-polymerase to detect the presence of specific fragments of DNA in a sample.
How is DNA-PCR used in veterinary medicine?
DNA-PCR is most commonly used in veterinary medicine to detect the presence of infectious organisms, such as viruses, bacteria, and some types of parasites. Less commonly, DNA testing is used in breeding animals to determine parentage, to detect genes responsible for heritable disease, and to look for genes that control specific characteristics such as coat color.
How does DNA-PCR work to find infectious organisms?
"...each organism has a unique section
of DNA that is just like a fingerprint"
The principle behind DNA-PCR is that each organism has a unique section of DNA that is just like a fingerprint. When the unique DNA sequence of a particular organism is known, a diagnostic "probe" can be created. Then, using DNA-PCR, the probe can 'search' the sample to determine if the organism concern is present; if the probe find the "fingerprint" DNA sequence, it means the organism is present.
Is DNA-PCR a good test?
The DNA-PCR is excellent test for many reasons. It is especially useful for detecting extremely small numbers of infectious organisms, and for detecting infectious organisms such as viruses and some bacteria that are difficult to diagnose by other methods. It is often more economical than traditional methods of diagnosing infectious disease, and results are usually available in just a few days.
Can the DNA-PCR test be wrong?
No, any diagnostic test can be wrong - including DNA-PCR. Success with DNA-PCR depends on submitting the proper sample and collecting the sample before treatment is started. The DNA-PCR is a techincally demanding procedure, and laboratory error may occur due to contamination of the sample or poor technique. However, the error rate is extremely small especially if the sample is sent to a qualified laboratory where the potential for error is minimized through the use of strict safeguards and highly trained professionals. The enormous diagnostic power of DNA-PCR greatly outweighs its weakness, and provides veterinarians with a valuable tool in the battle against infectious disease.
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