Biology

DNA fingerprinting is a technique that involves use of DNA to identify individuals. Before it was discovered, it was difficult to solve some of the crimes in which little or no evidence had been left. Disputes such as paternity disputes were almost impossible to solve. But with the discovery of this technique, many cases have been solved and disputes settled through its help. This paper is going to look at the principles behind this technique and benefits it has brought with it.

Deoxyribonucleic acid (DNA)
Deoxyribonucleic acid (DNA) is a thread of molecules that are part of the cell structure which are commonly found in the nucleus of the cell. It is referred to as genetic fingerprint simply because each and every individual has different DNA except for identical twins who have the same set of DNA patterns. Each individual has a unique DNA profile just like in the case of finger prints. DNA can be extracted from the body tissues by taking samples such as body fluids, hair, saliva, tears and other body fluids or other things that contain DNA. Therefore, DNA finger printing is the process by which a subject is identified through the use of DNA (Christopher, 1991).

It is believed that each person has got a DNA profile that is unique just like finger prints. Over 99 of the 3 billion nucleotides contained in human DNA are said to be identical in all individuals. However, in every 1000 nucleotides inherited, there is a site that varies within the population which is referred to as polymorphism. Polymorphism is the one responsible in changing the length of DNA fragments that result from digestion of restriction enzymes. These fragments which result after digestion are referred to as restriction fragments length polymorphisms (Lorne, 1993). The techniques used in DNA finger printing were first discovered in 1984 by Alec J. Jeffreys, a geneticist of the University of Leicester in Britain while studying a myoglobin gene which is responsible for storage of oxygen in the muscles. He discovered that the gene is comprised of many segments which vary in composition and size from one individual to the other and that they had not particular function. He referred them as minisatelites which were found to form less than 1  of the total DNA in human beings. He went ahead to separate several of this minisatelite genes and inserted them in bacterias producing huge amounts of DNA segments (Terry, 1991).

There have been numerous researches which have been conducted in the human genetic engineering field since the first one which was conducted by Sir Alec Jeffreys.

The first step in undertaking DNA fingerprinting is to collect DNA samples from subjects. DNA sequences have been found to be in a paired helix strand form. These strands are then separated by use of different techniques such as the use of electrophoresis gel. Electrophoresis gel works on the principle of separation of DNA sequences through the use of charges. Once separation of sequences has been achieved, their images are further analyzed by the use of radio enzymes that stick to the isolated DNA strands or through the use of chemiluminescence technique. In cases where the images cannot be clearly seen, the process is repeated severally until a clearer image is obtained.    

Uses of DNA testing
According to Michael, Schmidtke  Jrg (1998), DNA finger printing has widely been used in forensic science for provision of evidence and identification. Through the use of the unique DNA composition of individuals which is found in materials belonging to them, it has been possible to generate DNA profiles for every individual. It is because of this that shocking crimes have been solved not forgetting the role that it has played in providing an insight into the history of human beings (Lorne, 1993).
 
This technique was first used to solve a criminal case in 1987. Since then, DNA evidence has been used in a variety of other court cases because evidence gotten from this technique has been considered as reliable because of the level of accuracy of the DNA results. Although it has been accepted as a source of evidence and a basis for convictions in courts, other individuals are opposed to its use. They query the accuracy of this technique because of the use of segments of DNA in contrast to the whole DNA strand. Despite the opposition, DNA fingerprinting has helped investigators and police to solve a lot of crimes that previously could be difficult to solve. It is through the help of this technology that cold cases with minimal evidence have been solved. This has been made possible because of the DNA data base with blood samples from offenders which have been established allowing investigators to look for DNA matches for materials that have been retrieved from crime scenes. (Christopher, 1991)
DNA finger printing has also helped solve paternity disputes and identify bodies in cases involving fatal accidents in which victims cannot be physically identified or in cases where there is mass fatality. This technique can also be of help in cases involving switching of infants during birth or when an adopted child requires hisher family medical history. Although there are usually challenges in cases involving mass fatalities, scientists have been able to extract and analyze samples regardless of the level of fragmentation and deterioration of remains (Terry, 1991).

DNA profiling has also been used in geological studies. The study of DNA structures together with differences in gene traits has made it possible to re-examine the different aspects of the history of human beings such as migration patterns making it possible to test the modern believes concerning genealogy and race. Its though this studies that scientist have been able to determine genealogical lines of ethnic groups which are considered not to be having any relationship shading light on past interaction and migration among different groups of people (Marina, 2006).

DNA change which have taken place for the last 20 years
Since its discovery, DNA finger printing has had an effect on thousands of peoples lives the world over. It continues to advance as there are numerous powerful technologies that have been discovered and continue to be discovered which have had a great impact on genetic studies. In 1978, this technology was used in studying inherent differences in Human DNA which led to the discovery of RFLP type of variation which results from altering single bases in DNA. It is through that discovery that it was discovered that there are approximately 10,000,000 different areas in which individual DNA can vary in sequence. It was again discovered that some regions in the DNA are more variable than single base regions known as minisatellites (Sergio, 1993).

It led to accidental development of DNA fingerprinting in 1984 by Sir Alec who demonstrated that a single test was capable of distinguishing every individual on earth. Sir Alec has also been able to come up with an approach to solve crossover and mutation problems among families by coming up with alternative ways of solving the problem through screening sperms. He has been able to reveal the way in which minisatellites mutate by use of abnormal recombination which has come to regulate the basic rules on how crossovers happen across human DNA and the effects it has on genetic diversity among the population (Sergio, 1993).