What is a DNA test?

A DNA test compares DNA (deoxyribonucleic acid) samples from two people and allows family relationships to be proved or disproved to a very high level of accuracy.

One very common reason for a DNA test is to find out if someone is the biological father of a child (paternity test), but there are many other uses and tests. Click here to order your testing kit.

Since all our body cells contain DNA, skin cells from the lining of the cheek provide a simple and convenient source for collecting a testing sample.

Purified DNA from these cells is compared to parallel samples of DNA from a family member or potential family member, and the variations on different chromosomes are read out by a DNA analysis machine to yield an overall signature somewhat like a bar-code. When the net DNA ‘bar-codes’ from family members are lined up next to each other it is possible to spot a biological relationship between them. In the case of offspring from true biological parents half the bands (stripes) in the bar-code like signature will line up with those of the mother, and half will line up with those of the father.

If on the other hand, there is no biological relationship between the test subjects there will be less than a 50% match in the bands.

DNA testing is the most convenient and scientifically accurate method of determining biological relationships between people.

How Is DNA Analysed In The Laboratory?

Polymerase chain reaction (PCR) is a technological process in molecular biology used to amplify and reproduce one or more copies of a segment of DNA – a method that takes about two hours.

PCR is made possible thanks to the enzyme DNA polymerase to combine a new strand of DNA to the preexisting strand available. DNA polymerase needs a primer (a strand of nucleic acid that serves as a starting point for DNA synthesis) to which it can add the initial nucleotide (the building blocks of nucleic acids), seeing as DNA polymerase requires a template 3’-OH group onto which to attach the first nucleotide. This natural requirement enables the scientist to focus and amplify on one particular section of the template sequence.

The initial stage of PCR subjects the double-stranded DNA molecule to high temperature, so as to divide the DNA polymerase strands from each other. The polymerase starts doing its job in building up new DNA Nucleotides, made up of the building blocks of DNA – A (Adenine), T (Thymine), G (Guanine), and C (Cytosine). By repetition of the stages of PCR and the raising and lowering of temperatures, the desired DNA strand is replicated a number of times, making it possible for the scientist to study the particular strands.

In DNA testing, scientific advances are combined the body’s natural processes in a non-invasive manner. The fast pace with which scientific discoveries develop, furthering our knowledge on our genetic makeup has never been easier and more accurate, and will only increase in being so.

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