What Is DNA
DNA (deoxyribonucleic acid) is made up of nucleic acids which determine many of your unique characteristics, ranging from facial structure to eye or hair color. Unless you have an identical twin, everyone's DNA is different, and uniquely yours.
Hair is a common way to get a DNA sample due to the low invasiveness that is needed to obtain the sample and because hair can provide a full sample of an individual's unique DNA. Hair samples are commonly found at crime scenes, and can be used as evidence.
Other Sample Types
Other mediums in which a DNA sample can be obtained include blood, semen, skin tissue, amniotic fluid and buccal cheek swabs.
Once a hair or other sample has been obtained, one of the first ways it can be tested is through restriction fragment length polymorphism (RFLP). RFLP examines two samples of DNA and looks for similar base pairs between the two samples to determine a match.
When not enough DNA can be obtained from a sample, polymerase chain reaction (PCR) tests are used. PCR tests take small segments of DNA and copy them over and over again until enough DNA is present to looks at specific genes and make a match. This method is not as accurate as RFLP testing, but can still determine a DNA match.
- Image by Flickr.com, courtesy of Michael Knowles