Answering the Question: What is DNA testing?

11 Aug 2017

DNA is our hereditary material and encodes all our genetic information. Answering the question ‘What is DNA testing’ is not easy and defies being explained in layman’s terms. The structure of our DNA has been studied for many decades but has only recently become part of the syllabus for young students studying biology. Many are still not sure what DNA actually is or does and understanding our DNA means understanding better how we are made.

A DNA Test vs DNA analysis

We could perhaps split hairs and say testing is related to the procedure involved in something and an analysis involves actually analyzing the individual components of a given substance. So essentially, doing a DNA Paternity test refers to the procedure involved which would include taking saliva samples. A Blood test would involve the medical blood draw. Both the blood and the DNA in these two tests would then be sent for laboratory analysis. However, for this article we are overlooking the difference between these two interdependent processes. Having a test without an analysis is just nonsensical.

DNA: What is it?

DNA is a long, long, convoluted molecule. It consists of two parallel strands that are intertwined together (try to picture a twisted ladder). Along the parallel strands there are bases simply referred to by letter A, T, G and C (adenine, thymine, guanine and cytosine). These base pairs pair together with the corresponding base pair on the opposite strand. The sequences of these base pairs form much of the basis of DNA testing and their order from individual to individual may sometimes be different or the same, depending on the location of the DNA analyzed.

Our existence, the formation and the functions of our body depend on our DNA; your hair colour, your height and your overall development, your sex; these all depend on your DNA. Even hereditary illnesses you may have heard of, such as diabetes and some cancers, are linked to your genes which are found in your DNA (genes are genetic segments of the DNA).

Chromosomes are large parts of the DNA and are the structures into which DNA is organized. We all usually have 46 chromosomes. All our genetic material, therefore, our DNA is stored in the cell nucleus. Understanding ‘what is DNA testing’ necessitates the need of the very basic information above.

Now onto the Question What is DNA testing?

If you have thought of doing a paternity DNA test and an infidelity test, it should be of interest to understand what DNA analysis/ DNA testing involves. There are a number of procedures available but only the two most relevant ones shall here be discussed.

Polymerase Chain Reaction is one procedure or method for analyzing DNA. This procedure allows your DNA testing to happen since it enables laboratory DNA analysts to make thousands of copies of the DNA with which they can work. The facts that even a small DNA fragment can be used, perhaps just a couple of cells, in PCR means that even degraded sample can be tested. The name PCR is derived from an enzyme used in the reaction which helps to read the DNA sequence. Forensic testing relies on this type of procedure as often there is little DNA to work with, a single hair or a cigarette butt that may have been left in the open for a long time. PCR is often frequently used in paternity DNA testing.

STR Testing: This procedure is also known as Short Tandem Repeat testing. A short tandem repeat is essentially a repeated pattern of bases on the DNA molecule. The method is an adaptation of PCR analysis and its use is widespread. The variations in the number of repeats from one individual to another form the grounds for distinguishing how close or distant the relationship is. Human beings share a large bulk of their DNA; however, STR testing allows locating those tiny sections of DNA which differ between individuals. These tiny differing sections are used to create a profile which is unique.

There is so much more to answer the question ‘What is DNA testing’? However, the information given above should be enough to help you have a good idea of the basis of most DNA tests.