How Are DNA Tests Done?
Did you know that DNA was only discovered in 1953 by scientists James Watson and Francis Crick? Despite the discovery being barely half a century old, we’ve already made leaps and bounds in science since then.
For instance, we’ve got a good grasp of how DNA works and how to test it for links. Today, DNA tests are commonly carried out for a wide variety of reasons, including paternity cases.
Are you curious about how DNA tests are done? Then keep reading. We’ll explain them in detail here.
What Are DNA Tests Used For?
First off: what are DNA tests even used for?
If you’ve grown up in the late 1990s or 2000s, then you’re probably familiar with Jerry Springer and Maury. You’ll know that DNA tests were used to determine whether or not a man is the biological father of a child.
But there are many other ways to use DNA tests. They can determine:
As you can see, DNA is quite powerful, and you can test it to determine quite a range of things.
How Are DNA Tests Done?
To test for DNA, you must first have a sample that contains the DNA. There are many ways to get DNA, such as spit, blood, or semen.
You can bring in a sample with DNA on it (such as clothing that has traces of any of the above) or you can have a professional swab you on the spot.
This is usually done in a painless manner, as they’ll just stick what looks to be a long Q-tip into your mouth and rub it against the inside of your cheek a few times. You’d have what’s known as an oral or buccal swab done.
Once the lab receives your DNA sample, then it’s time to get to work. In most cases, the DNA sample is divided up (usually in 2) so several tests can be done by different scientists. This ensures that the results are consistent.
Next, they’ll extract the DNA strands from the sample and purify it. That way, the scientists will work with just the DNA and no other “background noise,” such as other biological material from the cell. This is done by lysing the cells; the scientists will add an enzyme, which will break down the outer membranes of the individual cells.
At this point, there’s no enough DNA to work with. To get enough material, they’ll perform polymerase chain reaction (PCR).
What PCR does is take around 16 to 21 areas in DNA called loci, and multiply them by billions. This is done by adding a chemical mix to the extracted and purified DNA, which includes primers that’ll tag the building blocks of DNA. These consist of 4 nucleobases:
- Adenine (A)
- Guanine (G)
- Thymine (T)
- Cytosine (C)
The solution is then put through a thermal cycler (or a PCR machine). As the name suggests, this machine puts the DNA sample through multiple heat cycles. With each one, it doubles the amount of DNA you want to amplify.
Once PCR is done, the scientists have enough DNA to work with. But how exactly do they take a look at what’s in there?
Typically, the scientists will perform what’s called electrophoresis. While there are multiple types out there, gel electrophoresis is used for DNA profiling.
The scientists will load different DNA samples into separate slots or wells on the gel; they will load a DNA ladder into the first well, which are markers to compare the samples to.
They’ll then turn on an electrical current, which will cause the DNA samples to run from one end of the gel to the other.
On the gel itself, the different DNA fragments will separate, based on size. This is because the smaller the molecule, the faster and further it’ll travel. This allows scientists to get a closer look at the components found in DNA.
Once the gel electrophoresis is done, the gel will look as if nothing happened on it. This is because the DNA fragments are currently invisible to your eye.
To see the separation bands, scientists apply a dye, usually ethidium bromide. Once the gel’s soaked in this dye for a little bit, it’s put under a UV transilluminator. This allows scientists to clearly see where the DNA separation bands are.
Usually, these transilluminators are hooked up to a computer so the scientists can take pictures of these DNA profiles. These images are then sent to the appropriate parties to show whether or not there’s a DNA link between the parties.
DNA Tests at Home
You may have heard about DNA test kits for at-home use. Because you still send in DNA samples to a lab, these can work just as well as going to a DNA testing facility.
However, the main drawback is you can’t use these for legal reasons. So while it’s possible to, say, establish paternity with an at-home DNA test, you can’t use that evidence in court.
For that reason, if you’re trying to pursue a legal matter with DNA testing, it’s always a good idea to choose a DNA testing facility rather than do at-home testing. This can ensure you take legal action in the right way.
Get a DNA Test Done Today
Now that you know how DNA tests are done, maybe you’d like to order one for yourself. It can be especially helpful in getting answers for family questions or settling court cases.
If you’re pursuing legal action, then it’s highly recommended you seek out a DNA testing facility, as at-home tests will not be admissible in court. Make sure you start your case off on the right foot by choosing Health-Link DNA.
Do you have any more questions regarding DNA tests? Get in touch with us now and ask about our free consultations.
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