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DNA and Forensics In my essay I will discuss the topic DNA and Forensics. This is an interesting topic because there have been great advances in the field of forensic science that have affected its credibility and usage in solving crimes that would otherwise go unsolved. DNA can be found in almost any bodily fluid (semen, saliva, blood, etc. ) and in less obvious places such as a strand of hair. It has become a crucial part of investigating crimes, and will continue to develop this way.
DNA first came into use for forensic science in 1986. It was used by a scientist by the name of Alec Jeffreys and his colleagues from Leicester University. He was contacted by authorities to verify the confessions by a seventeen year old porter regarding a double rape-murder case. As it turns out, this boy proved to be the first murderer to be cleared as a result of DNA fingerprinting. (Joe Mickel and John F. Fischer, 1998) DNA can be found in such things as blood and semen. It can also be found in such things as tissue found beneath the fingernails of a victim after a struggle, it can even be found in saliva cells left on a mouthpiece of a telephone after a conversation.
DNA is everywhere in a persons body, and can not be replicated. It is unique to every person, but all blood relatives have similar qualities that make them identifiable. (Joe Mickel and John F. Fischer, 1998) DNA stands for deoxyribonucleic acid, and it basically looks like a twisted ladder, or a double helix with rungs or base pairs. Guanine (G), Adenine (A), Thymine (T), and Cytosine (C) are the four bases that make up the base pairs. The bases dont just pair with any other bases, there are certain predictable combinations: A with T and G with C, and these are true to any DNA. The human body contains in excess of three billion base pairs, only a few of these are what attract forensic attention. (Joe Mickel and John F.
Fischer, 1998) The first of the two procedures I will discuss is restriction fragment length polymorphism (RFLP). It is used most in forensic science, but one of the few draw-backs are that it requires a larger quantity of the DNA and it also is more labor intensive, takes up more time, and requires radioactive reagents that require special procedures in the lab. Among its many advantages are the ability to narrow down a specimen to a narrow part of the population, maybe one in billions. In contrast to RFLP, PCR (polymerase chain reaction) is easier to use and doesnt require a large sample of the DNA involved.
PCR can be applied to samples as small as a billionth of a gram. During PCR an enzyme known as DNA polymerase can be directed to duplicate a strand of DNA to duplicate several million times. This is the reason that this procedure can be applied to such small quantities. This provides enough of the sample for the testing / examining to begin. There have been many cases in which courts have challenged DNA evidence, such as if the examining was done at a private lab, the court could challenge the standards as to which the lab runs at. However, DNA testing is widely accepted across the world because it is such a precise, accurate method of identifying a suspect, or victim (if they should be poorly decomposed, etc. ) The DNA evidence could also be challenged because there is a great possibility that the samples and specimens to be examined, were: A: Not collected properly B: Not handled properly C: Falsified D: Contaminated DNA has taken years to develop and become accepted in court.
On January 22, 1986, Robert Melias became the first person to be convicted of a crime (rape) because of DNA evidence. Ever since the two cases discussed (the other case discussed in paragraph two) DNA has become a great tool in solving murder, rape, and other mysteries that would otherwise go unsolved.
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Research essay sample on Dna Evidence Base Pairs
