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The importance of dna profiling criminal investigation
Fingerprint in criminal investigation
About dna fingerprinting
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DNA Fingerprinting
It is widely known that each individual has a DNA profile as unique as a fingerprint. Actually, over 99% of all 3 billion nucleotides in human DNA which we inherit from each parent are identical among all individuals. However, for every 1000 nucleotides that we inherit there is 1 site of variation or polymorphism, in the population. These DNA polymorphisms change the length of the DNA fragments produced by the digestion of restriction enzymes . The resulting fragments are called restriction fragments length polymorphisms. Gel electrophoresis can be used to separate and determine the size of the RFLPs. The exact number and size of fragments produced by a specific restriction enzyme digestion varies from individual to individual.
DNA fingerprinting has proved valuable, not only for convicting felons and exonerating the innocent, but also for establishing maternity or paternity and proving family relationships. More exotic uses include the identification of missing children in Argentina, soldiers killed in war, and even the body of Nazi physician Joseph Mengele, the so-called "Angel of Death."
The way it started:
The fundamental techniques involved in genetic fingerprinting were discovered serendipitously in 1984 by geneticist Alec J. Jeffreys of the University of Leicester in Great Britain while he was studying the gene for myoglobin, a protein that stores oxygen in muscle cells. He found that the myoglobin gene contains many segments that vary in size and composition from individual to individual and that have no apparent function. Jeffrey called these segments minisatellites because they were small and they surround the part of the gene that actually serves as a genetic bluprint.
We concluded that it is possible to examine small amounts of DNA by first replicating the sample using Polymerase Chain Reactions then using gel electrophoresis to. determine the genotype of the DNA. The main goal for our experiment was to learn how to examine DNA when there is only a small sample present. We examined the samples of DNA obtained from student hair using the replication method of Polymerase Chain Reaction and the inspection method of gel. electrophoresis.
DNA is the blueprint of life. It stores our genetic information which is what is in charge of how our physical appearance will look like. 99.9% of human DNA is the same in every person yet the remaining .1% is what distinguishes each person (Noble Prize). This small percentage is enough to make each person different and it makes identifying people a lot easier when its necessary. DNA not only serves to test relationships between people it also helps in criminal cases. DNA testing in criminal cases has not been around for many years if fact it was not until the early 1990s when the use of DNA testing for criminal cases was approved and made available. By comparing the DNA of a suspect and that found in the crime scene a person can either be convicted of a crime or they can be exonerated. This method of testing gained more publicity in the 1984 case of Kirk Noble Bloodsworth a man who had been convicted of the rape and first degree murder of a nine year old girl in Maryland. His case was a milestone in the criminal justice system since it involved the use of new technology and it also raised the question of how many people had been wrongly incarcerated for a crime they did not commit.
In our genes, multiple different alleles determine whether one person will have a certain trait or not. Alleles are what make-up our genotypes and in this lab, we wanted to determine the genotypes of our class in the two loci: TAS2R38 and PV92. The TAS2R38 locus codes for a protein that involves the bitter taste of PTC; the gene determines whether or not a person will taste the PTC paper as very bitter or no taste at all. People with the “T” allele are tasters while those that are homozygous recessive (tt) are non-tasters. The taster locus can be found chromosome 7.3 The two different alleles present in the could be due to the effect of evolution and natural selection because the same can be found in chimps.4 The PV92 locus does not code for any protein but rather involves an Alu element that is 300-bp long. A person with the “+” allele would have the Alu element making that sequence longer while those with the “-“ allele don’t have the element and would have a shorter sequence. This locus can be found on chromosome 16.3 There are multiple Alu sequences found among primate genomes but there are human specific sequences such as the one found on the PV92 locus.1 In the experiment, student DNA was collected from cheek cells and PCR was used to target the loci and amplify the region of DNA. In the taster gene, after amplification, a restriction digest was performed to differentiate between the two alleles. The digest was able to show differentiation because those with the “T” allele would have two bands from gel electrophoresis and those with “t” will have one band because the restriction enzyme doesn’t cut it. For the PV92, we were able to distinguish between the alleles due to the added length of the Alu element. Those...
. DNA can be left or collected from the hair, saliva, blood, mucus, semen, urine, fecal matter, and even the bones. DNA analysis has been the most recent technique employed by the forensic science community to identify a suspect or victim since the use of fingerprinting. Moreover, since the introduction of this new technique, there has been a large number of individuals released or convicted of crimes based on DNA left at the crime scene. DNA is the abbreviation for deoxyribonucleic acid.
Keiper L. More states use familial DNA as powerful forensic search tool. Reuters [Internet]. 2011 [cited May 16 2012]; N. page. Available from: http://www.reuters.com/article/2011/03/30/us-crime-dna-familial-idUSTRE72T2QS20110330.
Easteal, McCleod, and Reed. DNA Profiling: Principles, Pitfalls and Potential. Switzerland: Harwood Academic Publishers, 1991.
States. The FBI performs testing for free to all police agencies to help keep costs down
It was in 1984 when Alec Jeffreys, a British geneticist, discovered that specific sequences of DNA did not add to the function of a gene but were still constant throughout it. (Britannica). Jeffreys called these minisatellites and determined that each individual organism had a unique arrangement of minisatellites (Britannica). In the early uses of DNA fingerprinting, it was only used for identifying genetic diseases and disorders but people quickly realized that it could be used in many different areas of science (hubpages). Years after the discovery of DNA fingerprinting, it had been used to solve the first immigration case, the first paternity case, and even helped identify the first identical twins (le.ac.uk). The first methods of DNA fingerprinting were accurate, but you would have had needed to acquire a large amount of DNA. Over time, the advancement of science has led to major advances that formed the basis of DNA profiling techniques. These newer methods are still used today and allow scientist to use skin, blood, semen, and hair to gather DNA (le.ac.uk). In 1988 DNA fingerprinting was used for the first time in a criminal investigation. Timothy Spe...
DNA in forensic science has been around for a long time. DNA has had help in solving almost every crime committed. There have been a lot of crimes where people are raped or murdered and the person who did it runs free. Scientists can collect the littlest item they see at the scene, such as a cigarette butt or coffee cup and check it for DNA. People have spent years in jail for a crime they didn’t commit till DNA testing came into effect. People are getting out of jail after 20 years for a crime they didn’t commit, cause of the DNA testing. DNA has helped medical researchers develop vaccines for disease causing microbe. DNA has become a standard tool of forensics in many murders and rapes.
Tsou, J. A., Hagen, J. A., Carpenter, C. L., & Laird-Offringa, I. A. (2002, August 05). DNA
Once a crime has been committed the most important item to recover is any type of evidence left at the scene. If the suspect left any Deoxyribonucleic acid (DNA) at the crime scene, he could then be linked to the crime and eventually charged. A suspect’s DNA can be recovered if the suspect leaves a sample of his or her DNA at the crime scene. However, this method was not always used to track down a suspect. Not too long ago, detectives used to use bite marks, blood stain detection, blood grouping as the primary tool to identify a suspect. DNA can be left or collected from the hair, saliva, blood, mucus, semen, urine, fecal matter, and even the bones. DNA analysis has been the most recent technique employed by the forensic science community to identify a suspect or victim since the use of fingerprinting. Moreover, since the introduction of this new technique it has been a la...
Deoxyribonucleic acid (DNA) is an acclaimed extraordinary discovery that has contributed great benefits in several fields throughout the world. DNA evidence is accounted for in the majority of cases presented in the criminal justice system. It is known as our very own unique genetic fingerprint; “a chromosome molecule which carries genetic coding unique to each person with the only exception of identical twins (that is why it is also called 'DNA fingerprinting ')” (Duhaime, n.d.). DNA is found in the nuclei of cells of nearly all living things.
"Using DNA to Solve Crimes." U.S. Department of Justice: National Institute of Justice. (September 9, 2014). Web. 29 May 2015.
Fingerprint usage dates back to the 1800s. Sir William Herschel used the prints as signatures on civil contracts, before they were found useful towards crimes (History of Fingerprints Timeline, 2012). A British surgeon, Dr. Henry Faulds, wrote about using fingerprints for personal identification. He first looked at prints on clay pottery and studied the ridges and patterns that they had made in the clay. In 1891, Juan Vucetich suggested to start fingerprinting criminals to keep the prints on record. The following year, Vucetich identified a print from a woman who killed her two sons. Investigators found her print and were able to correctly match her identity. Charles Darwin’s cousin, Sir Francis Galton, wrote and published the first book about fingerprints. He wrote about how every individual has a unique print by the certain traits of each fingerprint (History of Fingerprints, 2012). The popularity of fingerprints grew greatly in the United States in the early 1900s. Police departments and the FBI began to use the...
...ary part in genotypes of potential interest that human geneticists breeders, as well as evolutionary geneticists are investigating. However, although we have the capability to unravel experiments that the founders of quantitative genetics would have never imagined, but their basic, un-computational machinery that they developed is most easily adaptable to the latest analyses that will be needed. We are far from ‘letting-go’ molecular biologists from the mathematical techniques/systems, because this age in respect to genomics has been forced into accepting gratitude due to the major importance of quantitative methods as opposed to the new molecular genetics. As geneticists tend to map molecular variation as well as genomic data, quantitative genetics will be moving to the front position because of its relevance in this age of rapid advancement in molecular genetics.