DNA Fingerprinting - Research Paper Example

DNA Fingerprinting DNA fingerprinting is a laboratory procedure that has proved very useful in personal identification. With its wide applications, it is causing a revolution in the modern world. Typing of DNA presents unique profiles for each individual except identical twins. The high rate of variation results because DNA fingerprinting relies on non-coding hyper-variable sequences to produce a unique pattern of bands for each individual. DNA profiling relies on the discovery of a broad range of restriction enzymes and their specificity. DNA typing has a wide range of applications from paternity testing, criminal investigations, and population studies to identification of tragedy victims. Other applications are in conservation biology and evolution studies. However, DNA typing presents its challenges especially concerning the amount of sample and accuracy of the process. Introduction DNA fingerprinting has caused a revolution in the world since its description in 1985. Deoxyribonucleic acid is present in all body cells. DNA consists of a sugar, four nucleotides, and a phosphate group. The nucleotides commonly called bases differ in the frequency of occurrence and the order in which they occur. The general DNA structure is similar in all individuals. However, the order and frequency of bases brings a remarkable difference between individuals. DNA fingerprinting presents a profile of an individual’s DNA. The four bases namely adenine, cytosine, thymine, and guanine form unique sequences on the two DNA chromosomes. Studies reveal that there are sequences that encode for essential proteins that are necessary for all cell functions. Geneticists called these coding sequences exons. In addition, there are non-coding sequences, the introns. Studies have revealed that the coding sequences are present in every individual because they code for proteins that drive the life process. These sequences have great similarity in individuals and display limited variation. On the other hand, the non-coding sequences portray a high level of variation and form the basis of DNA profiling. Basis of Fingerprinting DNA profiling is currently the most powerful tool in individual identification. It utilizes the variation of the non-coding sequences to produce unique profiles for each individual (Starr et al 247). The variation in these sequences is too high and this minimizes the probability of two individuals having identical profiles to virtually zero. Due to their high level of variability, geneticists call them hyper- variable regions. These regions consist of about ten to fifteen core sequences that may repeat themselves severally at different locations in the chromosome. The non-coding regions appear in between the coding regions. The frequency of repetition of these highly variable regions results to the differences among individuals. Studies indicate that only identical twins produce similar DNA profiles. The reliability on DNA profiles overrides the traditional fingerprints. The environment contributes greatly to the patterns of the fingers of an individual and the method presented its challenges. DNA fingerprinting presents a great potential in providing accurate profiles that can differentiate two individuals. Closely related individuals display a level of similarity in the profiles depending on the level of correlation. Procedure of Running a DNA Fingerprint DNA fingerprinting is laboratory technology involving several procedures. The discovery of restriction enzymes, which cleave DNA at specific recognition sites, formed the stepping-stone to DNA fingerprinting. The initial step in DNA typing is the isolation of DNA from the sample. Samples may be blood, cells, saliva, urine, hair follicles, bones, teeth, and hair fragments (Read 21). Geneticists recognize the existence of both nuclear DNA found in the cell nucleus and mitochondrial DNA in the mitochondrion. The amount of sample available determines the type of DNA isolated. In cases where small samples are available such as hair fragments, bone, and teeth, mitochondrial DNA is isolated. Studies have revealed that mitochondrial DNA exhibits a higher variation and geneticists may prefer it in some cases. The second step involves cleaving the isolated DNA into fragments. Restriction enzymes have the capacity to recognize and cleave specific sites in the DNA. The sites recognized by restriction enzymes are the repetitive hyper-variable regions. Different enzymes cleave specific sequences and produce DNA fragments of varying sizes. These fragments undergo separation according to size by gel electrophoresis. Gel electrophoresis utilizes two properties to separate the fragments (Read 22). The process runs in an electric field that generates charge. Since the fragments are charged, they move towards the side with a charge opposite to the negative charge on the DNA fragment. The longer fragments move slowly across the gel, while shorter fragments move faster. In the next process, transfer of the DNA fragments to a nylon membrane occurs. The DNA fragments attach to specific positions on the membrane. After transfer of the fragments to a nylon membrane, probing follows. Probing involves the attachment of radioactive complementary short sequences to the DNA fragments on the nylon membrane (Read 23). These probes attach at the end of the fragment and enable visualization of the fragments under x-ray films. The probes have an Ethidium bromide stain, which is a radioactive component. Visualization is the last step and involves viewing of the fragments on the nylon membrane under x-ray film. Photography of the resulting bands produces unique patterns for each individual. An Ethidium bromide stain is responsible for the alternating dark and light shades of black that result. Applications of DNA Fingerprinting DNA fingerprinting presents an elaborate profile of bands that represent the fragments produced by restriction enzymes. An examination of two profiles of unrelated individuals presents a high level of variation. On the other hand, presence of similar bands on two profiles depicts a level of similarity and occurs in related individuals. The potential of DNA profiling to present such elaborate profiles is the cause for its wide application. One of the applications of DNA profiling occurs in paternity testing (Read 17). Cases that require identification of the parents of a child arise so often in society (Lau 31). DNA profiling provides the absolute truth when potential fathers deny their responsibility. In domestic cases whereby several fathers claim to be the real fathers of a child, DNA fingerprinting comes in to solve the mystery. An analysis of the DNA profiles of the potential fathers and the child determines the level of similarity. The real mother or father shares a close similarity of several bands with the child because of shared genes, and this acts as evidence of paternity. DNA fingerprinting has solved multiple paternity cases in the society. Criminal investigations are taking a different course in the modern society due to the availability of DNA profiling. The samples collected from crime scenes serve as DNA samples and provide a DNA profile of the suspect (Lau 32). Suspects of the crime donate samples of DNA for typing and comparison with the profile obtained from samples on the crime scene. The real culprit’s DNA profile must match that obtained from the crime scene. DNA profiling helps in proving some of the suspects innocent and serves as evidence for the criminal in court. However, there are challenges in its application in this field especially when it is a requirement for relatives to produce DNA samples. For some people, it implies interference to enjoyment of one’s rights. Cases of manipulation and human errors in the procedure are a cause of concern. Nevertheless, application of the process with integrity can help in determination of the real criminal. DNA fingerprinting has proved to be of potential use in frauds that involve impersonation. DNA fingerprinting identifies persons and solves the frauds. In other cases, DNA profiling helps families and doctors understand the susceptibility of some genetic diseases that run down some family trees. Profiling of DNA helps the family members understand the cause and make predictions of its occurrence in the future. Equipped with such information, such families can make the right choices in future (Dunphy 12). In addition, DNA profiling is a useful tool in mapping changes in populations (Read 17). Genetic markers identified in populations help in making DNA profiling helpful in determining migrations of people. Geneticists have described these markers as sequences at a specific position, possessing the ability to run down from a generation to the next without changes. DNA profiling traces these markers and their presence helps in the analysis of possible migrations. DNA profiling has helped in victim identification of recent tragedies. In fire, war, murder and any other accident or tragedy, victim identification presented major challenge before the invention of DNA profiling. However, currently, relatives of the victims of tragedies donate DNA samples that on typing present profiles for comparison with samples from the remains of the victims. In the September 2001 American attack, DNA typing identified a great number of the victims (Lau 32). Other projects utilizing DNA profiling include the Shoah project. DNA typing has wide applications in conservation biology, forensics, and evolutionary studies. In evolution, comparison of ancient samples of species with the current species presents useful information in understanding the evolution theory. Conservation biology deals with conservation of species. DNA profiling helps establish the profiles of species that are prone to extinction. Such profiles are useful to conservation biologists and help them establish the best conservation strategies. Challenges of DNA Fingerprinting DNA fingerprinting presents its challenges in running the procedure and application. In some cases, available cases do not present enough DNA to develop a viable profile. DNA is prone to easy degradation and this presents a great challenge. The use of short tandem repeats is a potential solution in cases that present minimal amounts of DNA. Human error occurs and produces unreliable profiles. In some countries, people are not willing to produce DNA samples and this limits the application. Conclusion DNA profiling is creating major impact in the world. It presents a unique profile for each individual and eases the process of personal identification. Improving the precision and accuracy of the procedure will reduce the challenges that drag its application down. However, the procedure deserves credit for its current applications. Improving the procedure will ensure that criminal investigation will be easier. DNA profiling is truly a scientific milestone in forensics. Work Cited Dunphy, Cherie. Molecular Pathology of Hematolymphoid Diseases. Chicago: Springer, 2010. Print. Lau, Terence. Singapore Law Gazzete. DNA Fingerprinting and Its Application in Forensic Science. Web 09, Mar. 2012. http://www.hkdnachips.com/publications/200511Singapore.pdf Read, Marina. Focus on DNA fingerprinting research. New York: Nova Publishers, 2006. Print. Starr, Cecie. et al. Biology: The Unity and Diversity of Life. New York: Cengage Learning, 2008. Print. Read More