What is DNA Testing?

07 Jul 2017

There is probably too much to say regarding the question ‘what is DNA testing?’ especially if you are thinking of doing a paternity DNA test or another DNA test. Over the years these two words (DNA testing) have featured all over the place, in forensic criminal investigation, celebrity paternity disputes and archaeological excavations of ancient human or animal remains. The list of course continues, but it is best to begin with the basics.

 What is DNA?

DNA is an acronym for deoxyribonucleic acid. DNA is where our genes are encoded and genes are the building blocks of life which make us who we are what we look like and predispose us to certain illnesses. To get an idea of what DNA looks like think of a ladder that has been just a tad twisted. DNA is a polymer (that is, it is made of many smaller molecules put together). It is extremely long and if seen under a microscope would like much like a ball of tangled string. Certain sequences of what are known as bases pair, which form part of the polymer, encode all the information we need. DNA is found in our cells and thus it can be found in our hair, bones, skin, and muscles to just mention a few. DNA makes us male or female, encodes our physical characteristics, can be the cause of genetic illnesses, tells our body which muscles to build, how to fight diseases – the list goes on ad nausea.

 Where does DNA come from?

DNA is something we inherited from our mother and father. In fact we inherit half our genetic material from our mother and half from our father. Our DNA is essentially unique and the chances of finding someone with our same DNA are minute and in fact even disregarded.

 So what is DNA testing?

DNA testing involves analyzing a person DNA profile which is much like a blueprint. DNA is far too complex to be thoroughly analyzed (although of course it can be done) but analyzing specific sections of the DNA molecule enable investigations to be carried out between relatives in for example a paternity DNA test or investigations involving criminals. Testing is normally done using a mouth swab which is rubbed inside the individual’s mouth to collect cheek cells (if you remember we said DNA is found in every cell with the exclusion of red blood cells). If the person is not available to give a cheek swab, there are many other samples one can use as long as there are human cells on it, even a chewing gum and a razor blade.

There are many ways in which DNA can be analyzed for your DNA test and the following are two of the main techniques used:

• PCR analysis: PCR or polymerase chain reaction allows analysts to make thousands of copies of your DNA and the procedure makes it possible for scientists to be able to work with these many copies. However, the first step would be isolating the cell nucleus from the other cells components by using a centrifuge and then bursting the cell nucleus in which the DNA is contained. PCR makes it possible to work with very small or even degraded DNA samples. DNA polymerase is an enzyme used in the analysis process and enable the amplification of the DNA sample and analyzing the specific loci of genetic markers needed in for example, a paternity DNA test.
• STR Testing: Short Tandem Repeat testing is another procedure for analyzing DNA and is commonly used in DNA testing. The procedure involves analyzing short sections of the DNA molecule; normally these sections would consist of 4 base pairs. Base pairs are found along both DNA strands and have bonds joining base pairs that are opposite each other (remember the ladder?). The repeated units vary between individuals that are unrelated which means STR can be very reliable to confirm whether related individuals share the same repeats to confirm a biological relationship.

There is more to fully answer the question ‘What is DNA testing’ but this should suffice as a general and basic description of what your relationship DNA test will involve.