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Restriction Enzyme Analysis of DNA Report    In every person, there are millions of different combinations of four nucleotides- adenine, thymine, cytosine, and guanine- which make people different. This means that each person has their own specific “DNA Fingerprint”, just like your own fingerprint, it is completely unique to you. Restriction fragment length polymorphisms can be used in DNA fingerprinting because they are once again unique to each person. The DNA fragment can be amplified and, using processes like gel electrophoresis, can be compared to another sample of DNA. There is also DNA profiling, which is very similar to your DNA fingerprint in that it is unique to each person. It uses the number of short tandem repeats (STRs) within non-coding regions of the DNA to separate people from one another. The STRs will be placed in a polymerase chain reaction machine (PCR), in order to amplify the DNA for comparison. Inside of each PCR tube, there needs to be special primers for annealing, the sample of DNA, Taq polymerase and free nucleotides. First, the DNA is denatured through heat shock in order to break apart the hydrogen bonds. Then, the PCR machine cools down to allow special primers inside the tubes to anneal or attach to the strands of DNA. Next, the machine heats up again in order to extend the DNA with Taq polymerase enzyme. This process is repeated many times. Both of these methods of DNA fingerprinting and DNA profiling can be used in the criminal justice systems to either free innocent suspects or put guilty ones in jail.      After a PCR machine amplifies specific segments of DNA, using gel electrophoresis is the possible next step in comparing samples of DNA. Gel electrophoresis uses a sugar gel base, usually agarose, with pre-made wells to hold different DNA samples. A DNA marker is used to determine lengths of each individual DNA fragment in electrophoresis. It is put alongside the other samples of DNA, and each marker contains DNA molecules with known molecular measurements. The marker lengths are used In comparison to the collected samples of DNA to tell how long each fragment actually is. A graph-like structure is used, with the distance on the x-axis and the logarithm on the y-axis. DNA is negative, so the samples begin at the negative end and move towards the positive end once electricity is introduced. The shortest DNA fragments move the farthest down the gel.     In this criminal case, a man was brutally attacked while at an automated teller machine. He was beaten to death by his attacker. A witness saw the suspect and picks him out from a photo lineup. As it may be, the suspect chosen has a brother who looks exactly like him. Thankfully, the victim put up a fight during his attack and clawed at the perpetrator. Experts in forensics took samples of both skin and blood from underneath the fingernails. Blood samples were taken from each brother to be used for comparison. Each sample was labeled either X or Y and two separate PCR reactions were used. The first set of primers were labeled X-1 and Y-1 and the second set were labeled X-2 and Y-2. After the gel electrophoresis was completed, it was found that suspect Y committed the crime. The FBI itself has a total of 13 core loci for its Combined DNA Index System (CODIS). There are different loci such as US core locus, German core locus and European recommend locus (STRBase).

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