DNA
DNA, as you may know, is the human genetic material. It is different in each and every human, with the exception of identical twins. Science and many other fields have taken advantage of its unique properties in many ways, from medical advancements and research to criminal identification. DNA fingerprinting uses an impression or “fingerprint” of a strand of a person’s DNA. The impression can be compared to other impressions of DNA from a crime scene to determine guilt, from a child or parent to determine biological parentage, or can be examined for unusual properties that may indicate some medical condition.
Creating a Fingerprint
DNA fingerprinting is a laboratory procedure that requires six basic steps in all cases. First, the DNA must be isolated. This can be done by taking cells from body tissues such as hair, skin, or blood. Only a little bit is needed, such as the amount at the root of one hair.
Second, the DNA must be cut, sized, and sorted. Special enzymes are used to cut the DNA in specific places, and then the pieces are sorted according to size by being passed through a gel made from seaweed. This is similar to passing sand through progressively smaller screens to separate individual piece sizes. Third, the DNA is transferred to a sheet of nylon. This is done by placing the nylon on the gel and soaking it overnight.
The next step is to add radioactive or colored probes to the nylon sheet, which will produce a pattern known as the fingerprint. Each probe will typically stick in only one or two places on the entire nylon sheet. The final step is to create a whole fingerprint by using multiple probes at the same time. The print generally will resemble a bar code like one used by a grocery store scanner.
Uses of Fingerprinting
DNA fingerprinting can be used in many different beneficial ways. One of the most useful and common ways this procedure can be used is to diagnose inherited disorders in both unborn and newborn babies. Disorders that are commonly looked for may include cystic fibrosis, hemophilia, Huntington’s disease, familial Alzheimer’s, sickle cell anemia, and many others. This information can be used to prepare parents for the risk of having an affected child, or to help prospective parents make decisions about pregnancy.
Fingerprinting can also be used in the development of cures for inherited disorders. Studying the fingerprints of relatives or comparing those of large groups of people can identify patterns associated with the disease in question, which is the first step in finding an eventual cure.
Identification is another major use of this type of fingerprinting. DNA can be used to identify biological parents of children, and also to indicate the presence of a criminal at a crime scene. It can also be used in some cases to identify casualties of major disasters or missing persons.
DNA fingerprinting is a scientific advancement that has made many things much easier in research and identification, and its usefulness is continuing to increase.
By Kristin Cleveland