What Is Dna Fingerprinting?

What is DNA Fingerprinting?

The chemical structure of everyone's deoxyribonucleic acid ,DNA, is the same. The only difference between people, is the order of their base pairs. There are millions of base pairs in each person's DNA, that every person has a different sequence. Every person could be identified solely by the sequence of their base pairs, but because there are so many base pairs, the task would be very time- consuming. Instead, scientists are able to use a shorter method because of repeating patterns in DNA. These patterns do not, however, give an individual "fingerprint" but they are able to determine whether two DNA samples are from the same person, related people, or non-related people. Scientists use a small number of sequences of DNA that are known to vary among individuals a great deal, and analyze these to get a certain probability of a match.

Discovering DNA Fingerprinting

DNA fingerprinting has become an important part of society. It has helped to prove innocence or guilt in criminal cases. Also, it helps resolve immigration arguments and clarifying paternity. Its inventor, Professor Sir Alec Jefferys, University of Leicester, looks back at how it began. With highly automated and sophisticated equipment, the modern- day DNA fingerprints can process hundreds of samples a day. They had gotten to the point where they could detect single copies of human genes. This led to one of the first observations of introns, non-coding sections of DNA that split up genes. When Professor Jefferys came to Leicester in 1977, he wanted to move away from the study of split genes, and to use the new techniques of molecular biology with human genetics.

Types of Fingerprints

Human fingerprint patterns fall into three main groups: whorls, loops, and arches. Loops are the most common type, accounting for about 65 percent of all fingerprints. Whorls account for 30 percent of fingerprints, and arches for 5 percent. Each of the three pattern types have focal points which are used for classification. In the loop pattern there are two focal points: the core, or the center of the loop, and the delta. The Delta is the area of the pattern where there is a triangulation or a dividing of the ridges. When recording fingerprints, the delta and the area between the delta and the core must be completely recorded. A whorl pattern will have two or more deltas. For a whorl pattern, all deltas and the areas between them must be recorded. The arch pattern has no delta or core; but, it too, must be fully recorded so that its individual characteristics can be readily distinguished. Despite these broad patterns, each individual has a unique set of fingerprints, which can be used as a means of personal identification.

Fingerprinting Identification

For over 100 years, police agencies have had a powerful tool in combating crime. The use of fingerprinting allows crime fighters an extremely accurate means of identification. Other means of identification, such as hair color or style, weight or eye color, may change, but fingerprints do not. In earlier civilizations, branding, tattooing, or even maiming was used to mark and identify criminals. Although man had been aware of the fact that each person possessed a unique set of ridges on the fingers and hands, the use of these prints for criminal identification was not accepted until the early 1900s. The FBI Identification Division was born in 1924, with the receipt of 810,188 fingerprint