DNAAnalysis: A Critical Overview
DNAAnalysis: A Critical Overview
Forensicscience primarily entails the application of scientific methodologiesin criminal investigations with the aim of establishing standardizedadmissible pieces of evidence [ CITATION Pan03 l 2057 ].DNA analysis is one of the main forensic techniques used by lawenforcement bodies today. Analystsuse the technique to identify suspects since each individual hastheir own unique DNA profile. As detailed by Paneerchelvam andNorazmi, the technique is highly reliable but only if it is performedin accordance with the standard guidelines [ CITATION Pan03
l 2057 ].All in all, DNA analysis has over the decades revolutionized thescience behind detection of crime.
Thehuman body is designed in such a way that each and every cellcontains DNA (Deoxyribonucleic Acid) which in turn accommodates theindividual’s entire genetic program [ CITATION LiR08 l 2057 ].In each genetic program lies four subunits. These include Thymine,Cytosine, Guanine, and Adenine. Normally, the four are arranged insequences that are extensively long. The 20 amino acids are coded bycodons, which are made up of three bases. It is these amino acidsthat link up to form proteins. On the other hand, bases that cometogether to signal the termination of amino acid sequences arecommonly referred to as stop codons. Li details that there areapproximately 3 million base pairs which make up the human genome [ CITATION LiR08
l 2057 ].These base pairs harborinformation that is genetically relevant and necessary for individualcharacterization through the process of DNA analysis.
Therehave been varying methods used in the creation of DNA profiles overthe years. The earliest was RFPL, an acronym for restriction fragmentlength polymorphism. However, the method is irrelevant today since itrequires extremely large DNA samples and takes months to becompleted. Currently, analysts use polymerase chain reaction (PCR) asthe first step in creating DNA profiles. PCR’s sole purpose is toreplicate little amounts of DNA so as to create bigger analysissamples. The repetitive process involves heating DNA polymerase to 93degrees celsius. Heating the enzyme facilitate its binding to the DNAwhich in turn separates it into threads [ CITATION Pan03 l 2057 ].The end-result is STRs, and acronym for short tandem repeats. Theyaid in accurate DNA analysis since they are tiny hence making it easyto tell them apart. As alleles, STRs are arranged in what scientistspopularly refer to as VNTR (variable number tandem repeat sequence).On the other hand, alleles are alternately occurring gene pairs foundat specific loci on chromosomes. The Y chromosome is more prevalentin this case. Another common technique used in the replicating of DNAis AmpFLP (Amplified Fragment Length Polymorphism). It entails theuse of a restriction enzyme whereby PCR is used to amplify fragmentsand gel electrophoresis to sort them out.
DNAanalysts are one of the most popular forensic scientists today. Theirjob descriptions involve isolating DNA for various body fluids ortissues, after which they compare the acquired DNA to others in thedatabase so as to ascertain the individual`s identity. Typically, forone to qualify as a DNA analyst, they at least have to pursue aforensic science associate’s degree. However, those that preferworking in crime labs are required to pursue a graduate (bachelor’s)degree in biochemistry, genetics, or molecular biology. Courseworkspecifics include population genetics, molecular genetics, andstatistics. The three units are a must if one is to qualify as a DNAanalyst. In addition to this, one is required to complete acertification program overseen by the American Board ofCriminalistics. The prerequisites for the ABC certification include abachelor’s degree, passing their exam and at least two yearsworking as a professional forensic analyst [ CITATION Ame17 l 2057 ].Certificate exams specific to DNA analysts include the comprehensivecriminalistic test or/and molecular biology test.
Advantagesof DNA Profiling
WideRange of Samples
DNAprofiling does not require specific samples during processing. It canuse a wide range of samples from blood, saliva, urine, tears, semenand fingerprints. The samples are only required to have cells for theprofiling to take place. This is because genetic material is eitherfound in the nucleus and the extrachromosomal organelles such as theplasmids` transposons and insertion sequences. All these materialscontain genetic materials that are useful in the profilingprocess.The genetic material in these organelles is the same as thosein the nucleus of the cell.
Onecan also extract DNA samples from tissue cells. This can first bedone by processing tissue samples either manually or through a tissueprocessor. The tissues are processed into a monolayer of cells fromwhich DNA is extracted from each cell or one of the cells. Throughthis, they can carry out processes such as organ matching in theorgan donation process to make sure that the recipient`s body doesnot reject the organ. By the help of DNA profiling, there are moresuccessful transplants in the medical field ranging from heart,liver, cornea and kidney transplants among others[ CITATION fut16 l 1033 ].
DNAprofiling can detect the lowest number of DNA copies even among largeamounts of sample. This indicates that this method of analysis hasone of the lowest detection thresholds in the world of molecularbiology. It only requires one or two copies of DNA for it to profileand group an organism. High sensitivity is a useful tool in today`smedical world as it helps in the success of many experiments andtests. There is the need to have accurate results for each experimentthat is carried out especially in the research area because theresearch will be useful when it is applied.
Theresults of the tests are the determinant whether the procedure or themedicine will be applied. Sensitivity is mostly used in thepharmaceutical industry to test if certain medicines such asantiretroviral have been effective. Some of the medicines aremicrobial DNA inhibitors which means that they inhibit thereplication of the microbe DNA, and thus it cannot multiply eitherthrough the lytic or lysogenic cycle. DNA profiling can helpestablish the effectiveness of the medicine and if it is trulyinhibiting the replication of DNA. If it is inhibiting replicationthe number of DNA strands of that specific microbe will be the sameor lower than the original values before the patient began takingmedicine[ CITATION Ref17 l 1033 ].
Highspecificity refers to the ability of a test to detect the specificgene or sequence and profile it even in the presence of otherdifferent genes. DNA tests have a high specificity because eachorganism has a specific genomic sequence. There is the need for highspecificity tests in the medical field. They can be useful in theidentification of specific microbes for investigation. The test mustmaintain its integrity.DNA profiling has so far been one of the bestmethods to test for specificity. For instance, the results of thetests are the determinant whether the procedure or the medicine willbe applied. Specificity is mostly used in the pharmaceutical industryto test if certain medicines such as antiretroviral have beeneffective.
Someof the medicines are microbial DNA inhibitors which means that theyinhibit the replication of the microbe DNA, and thus it cannotmultiply either through the lytic or lysogenic cycle. DNA profilingcan help establish the effectiveness of the medicine and if it istruly inhibiting the replication of DNA [ CITATION Eas90 l 2057 ].If it is inhibitingreplication the number of DNA strands of that specific microbe willbe the same or lower than the original values before the patientbegan taking medicine. And thus the medicine will be targeting thespecific viral infected cells. This is important for testing theeffectiveness of various types of medicines against various diseasesor testing which is the most effective drug against a specificcondition or disease[ CITATION Wee17 l 1033 ].
DNA,also known as deoxyribonucleic acid, is the genetic substance foundin all organisms considered to be live. The genetic materialdetermines the functioning and the makeup of the organism. It is madeup of two complementary strands. It contains thiamine, adenine,guanine and cytosine which are stable organic chemicals. DNA is foundin two areas of the cell, in the nucleus and the extrachromosomalmaterials. In the nucleus it is found in the nucleolus and issurrounded by the nuclear membrane, it is highly coiled so that itcan fit in the nuclear space. DNA is also found in extrachromosomalmaterials such as plasmids which are found in the cytoplasm of cells.These materials can either be plasmids, transposons or insertionsequences. They are found in the cytoplasm of cells and DNA can bederived from them.
DNAhas several characteristics such as, it is supercoiled, it is doublestranded and it is hardy. This implies that cannot be easilydestroyed by other chemicals or organisms. It can withstand a lot ofpressure be it physical or chemical pressure. Physical and chemicalpressure is responsible for the breaking of the double strands intosingle strands. This requires a lot of effort and is normally doneusing machines which exert pressure or use chemicals to degrade thebonds between the sequences. It is quite hard to mutate a DNAsequence or erase it, and this is why DNA methods are most preferredby in laboratory [ CITATION fut16 l 1033 ].
TheDNA profiling process is computerized and thus is fast. The procedureonly requires that the sample is loaded into the machine and the restof the processes such as annulling or separation of the strands, thereading and the comparing of the strands are all computerizedprocesses that go on smoothly as long as there is no contamination.The results are given in real time once the sample processing isover. The computerized process is free of contamination and humaninterference, and thus it saves on time. The results one they areout, can either be printed or saved in the computer [ CITATION Wee17 l 1033 ].
Disadvantagesof DNA Profiling
Themost recent technologies are prone to errors caused bycross-contamination and thus they require a control or running thetests more than once to get the result that is accurate. Mostscientific procedures require accurate results for analysis. Theolder methods of DNA profiling are also prone to errors such asincorrect setting of controls and thus giving possible false positiveor false negative results. These errors are mostly brought about bycontamination it is, therefore, important to make sure that thesamples are not contaminated by either a similar DNA or any othermicrobe[ CITATION bet17 l 1033 ].
DNAprofiling can be easily manipulated by placing of evidence on thecrime scenes. Violation of privacy is also a disadvantage of thetest. DNA tests are a private matter to most individuals, therefore,one cannot have DNA profiling tests without permission/consent fromthe individual. There is a need for the consent to be in written formto avoid any possible lawsuits that may be filed by the individual.The possible instances that violation of privacy might occur includeduring crime investigation and paternity tests among others. Inpaternity tests, consent is required from both parties, but an ordermight be issued by the courts and the paternity test might not be adebatable issue. In criminal cases, the DNA profiling and matchingtests are important so as to find a solution and thus they are notdebatable once an order is issued. If they are taken without consentfrom the relevant authorities’ one faces the charges of violationof privacy[ CITATION bet17 l 1033 ].
DNAprofiling is one of the complex processes as it requires a fullyaseptic environment as the slightest form of contamination can causewrong results. There is a need for attention while following theprocedure. The chemicals that are to be used should be measuredcorrectly to avoid damaging of the sequences. The procedure is quiteeasy but operating and setting the machine might prove as a challengeto many individuals. Another area that might be a challenge might bethe calibration of the machine. Each sample has a different type ofcalibration, and thus it is important to set the machine to match thesample that will be processed to avoid damaging the sample and theDNA. The reading of the results can also prove a challenge tointerpret. Most DNA profiling machines print results as bar graphs oras statistical charts indicating the number of DNA copies that werefound in the sample [ CITATION fut16 l 1033 ].
DNAprofiling is quite an expensive process as the machinery and thechemicals used are quite expensive. The materials used in thisprocess are quite expensive. The machines also require special careand training which also requires money. The machine can only beplaced and managed by an institution which has a constant supply offunds for servicing and repairs in the case of breakdowns [ CITATION bet17 l 1033 ].
Needfor Special Training and Expertise
Thesemachines cannot be operated without special expertise. One is trainedon how the samples are prepared and fed into the machine. One is alsotrained on how to operate the machine and how to connect the machineto the internet for calibration and how to go about minor repairs onthe machine. One is also taught how to clean the machine if need beand the duration for which each type of sample is processed. Thesetraining can be conducted either weekly, monthly depending on theproblems that are encountered by the users[ CITATION fut16 l 1033 ].
DNAevidence was first used as evidence in a courtroom in 1985. However,it was not until the year 1988 that DNA evidence helped send acriminal to prison. Back then, all kinds of mathematical formulaswere posed against DNA evidence. All in all, some advancements havebeen made since then which have in turn made DNA analysis a morereliable means of providing evidence. Among them are the new testingmethodologies. Unlike RFLP, more recent procedures tend to be moreaccurate, faster and require small samples.
Moreover,new techniques have been introduced with the sole purpose of helpingDNA analysis fit all sorts of scenarios. Kinship and familialmatching are among the newly introduced profiling techniques. Theyaid in identifying bodies using DNA samples from family members. Thistechnique is especially effective in cases where multiple fatalitiesare recorded, such as airplane crashes. Y-STR DNA profiling isanother recent technique [ CITATION Rom13 l 2057 ].The Y chromosome is unique in that not only does it determine one’ssex, but is also inherited paternally. This technique aids indistinguishing between female and male DNA. More importantly, Y-STRprofiling isused in sexual assault cases whereby creating an accurate suspectprofile becomes difficult since sample acquired from thecomplainant/victim tend to be mixed up [ CITATION Smi15 l 2057 ].Anotheradvancement worth noting includes the ever-expanding DNA database.Before the year 2006, the DNA database comprised only of convictedfelons profiles. However, the 2006 law allowed for the addition offederal arrestees and suspected immigrants. To date, it is estimatedthat close to 1.1 million profiles are added to the database annually[ CITATION Smi15 l 2057 ].Therehave also been improvements with regards to training and handling ofDNA evidence. Personnel have been trained using more recent methods.Consequently, crime labs have come up with more efficient processingand evidence handling protocols. More so, prosecutors have turned tosavvier means of presenting all sorts of DNA-related evidence.
Inconclusion, it is safe to state that the DNA analysis industry issteadily progressing. It has come so far, so fast. As things stand,it is impossible to overlook the role this technique plays in thecriminal justice department. Many more advancements are still on thehorizon, which will make the method even more reliable. Undoubtedly,the future of forensic DNA methodologies is bright.
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