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Importance of DNA Running head: THE IMPORTANCE OF DNA IN AMERICA'S The Importance of DNA in America's Criminal Justice System An Honor's Thesis (HONRS 499) Erin Riehle Dr. Taiping Ho C/ Ball State University Muncie, IN April 2008 Expected Date of Graduation: May 2008 , P( . :1 (, ,r. I , ,I t Importance of DNA 2 LD 24;::j~ · Z4 ;~ Ll Acknowledgements • 5Lf I first and foremost want to thank Dr. Taiping Ho for not only being a wonderful, entertaining teacher, but also for guiding me through these last few years. I believe I would have been lost without you; thank you for your helpful advice and encouragement. I also wanted to thank my parents for understanding and allowing me to fall off the face of the earth for about a month so I could write this paper. I do appreciate your never-ending support. I also wanted to express my sincere gratitude to my best friend, Andrew Ardapple, who made me smile and laugh when I thought I would never finish this project; I do not think you will ever understand how much I appreciate the fact that you can ease the stress in my life. Last but not least, I want to thank Lindsay Leonhard for providing Dr. Ho with a hard copy of this paper while on was interning in Washington, D.C. Both you and Andrew are good friends. I do not think I could have made it through this journey without either one of you. Importance of DNA 3 Abstract DNA has garnered much media attention over the years, from the creation of television shows based on crime scene investigation to the broadcasting of several high profile murder cases. Yet, there is still some confusion on what this molecule is and how it can have such a powerful impact in the courtroom. This paper aims to provide both a clear understanding of DNA and an explanation of DNA analysis techniques as well as further exploration on how this substance has influenced court cases from the past to the present. Importance of DNA 4 The Importance of DNA in America's Criminal Justice System Introduction On December 21,2001, Larry Mayes felt the sun's warmth on his face as he walked out of the prison's gates ("DNA frees 100th," 2002). After 21 years of incarceration at the Indiana State Prison in Michigan City, IN, Mayes was finally a free man (Innocence project, 2007). Contrary to many assumptions, he was not out on parole; instead, he had been completely exonerated of a crime he was convicted of committing over twenty years earlier. Mayes's complete exoneration was in part thanks to DNA testing. Mayes's life changed over two decades ago; in October of 1980, a woman was working at a gas station in Hammond, IN when two African American males entered into the establishment (Innocence project, 2007). One of the men pulled out a gun, demanded money, and took the woman captive. She was beaten with the butt of the gun and forced to perform oral and vaginal sex on both men. After the rape, she was dropped offwhere she immediately contacted police; she was subsequently taken to the hospital where a rape kit was performed. Swabs from the victim's rape kit indicated the presence of semen, but serology tests did not yield conclusive results (Innocence project, 2007). Even though none of the fingerprints could be matched to Mayes and the victim was unable to choose him from a line up, the prosecution went forward with its case, because the victim was able to pick Mayes's picture out of an assortment of photos; the victim distinctly remembered that one of her assailants had a gold tooth and, therefore, she identified him by this trademark. Based only on the photo identification, Mayes was convicted on July 8, 1982, of rape, unlawful deviate conduct, and robbery (Innocence project, 2007). His punishment was 80 years in prison (Innocence project, 2007). Importance of DNA 5 In 1996, Mayes was given some hope for a future filled with freedom; the Innocence Project, a non-profit legal clinic that works to exonerate the wrongfully convicted through DNA testing, decided to work on Mayes's case (About the innocence, 2007). Together, with the Indiana School of Law, it was discovered that the rape kit used at the trial had been lost; however, a thorough search of the evidence room in the courthouse revealed the missing rape kit (Innocence project, 2007). A motion was filed to have the evidence undergo DNA testing. Results excluded Mayes as the source of the sperm from the rape kit. DNA had set Mayes free. Larry Mayes is not the only individual set free by DNA testing. Hundreds of wrongfully convicted individuals have been exonerated since this type of testing has become widely accepted and used ("DNA frees 100th," 2002). DNA testing has not only set the innocent free, but it also has turned the heat up on some cold cases by bringing assailants to justice after years of escaping the law. The purpose ofthis paper is to explain and elaborate on the importance of DNA in the criminal justice system. However, before discussing its impact, DNA should be first thoroughly examined. Understanding DNA Cells are the basic unit of life. Trillions of cells compose the human body, working together to complete daily bodily functions (National Center, 2004). However, just one cell is able to perfonn a variety of crucial activities. Each cell can take in nutrients, convert those nutrients into energy, carry out specialized functions, and reproduce ifnecessary (National Center, 2004). However, these specific activities cannot be completed without a certain set of instructions present in each cell. These instructions are known as deoxyribonucleic acid, which is more commonly known as DNA. Importance of DNA 6 DNA is crucial to the human body. Specific locations along the DNA structure code for the production of certain proteins, which are responsible for carrying out most of the body's complex tasks (National Library, 2008). These specific locations are known as genes, which are hereditary plans responsible for manufacturing certain proteins and giving each human being a unique appearance (National Human, 2008). Yet, the entire DNA structure is a nucleic acid found in almost each and every cell of the human body, including muscle cells, brain cells, liver cells, and others. DNA is consistent throughout the body and does not change during a person's lifetime, meaning the DNA found in liver cells is going to be the same as DNA found in brain cells (Turman, 2001). Yet, there are a few cell types that do not contain this directive molecule. Red blood cells do not contain DNA; blood, however, can be typed by the DNA that is housed in the white blood cells (Riley, 2005). Most DNA is housed in the nucleus of the cell; this type is known as nuclear DNA. Due to the fact that the nucleus is very small and has a limited amount space inside, the DNA molecule must be tightly packaged. DNA in this specific form is known as a chromosome. It is only forced out of this shape when the cell is preparing for duplication. DNA is also found in another cell structure known as the mitochondria, which is responsible for generating enough power for the cell to complete its specific tasks. DNA itself is a long string-like structure composed of two lengthy strands of nucleotides. These nucleotides are the building blocks of DNA. One nucleotide contains three very important components: a nitrogenous base, a phosphate, and a deoxyribose sugar (Luftig & Richey, 2001). The phosphates and sugars bond in an alternating pattern, thus composing the backbone of one strand of the DNA molecule. However, each DNA molecule contains two of Importance of DNA 7 these strands running in different directions and intertwining to create a double helix structure. The interior structure of the DNA molecule is composed of the remaining nucleotide component: the nitrogenous bases. Each nucleotide contains one of the following four bases: adenine (A), thymine (T), cytosine (C), and guanine (G). Inside the DNA molecule, the bases pair up; hydrogen bonds glue A with T and C with G, thus stabilizing the entire DNA structure (Riley, 2005). Because of these specific base pairings, the double helix is also known as being complimentary. Figure 1 is a displays the structure of a DNA molecule. Since water composes a large portion of the human body, adequate understanding of hydrostatic interactions is necessary in identifying the force holding DNA together. Because the sugar and phosphate groups are highly polar, the backbone that they create is also going to be polar, therefore making the exterior structure completely hydrophillic or attracted to water (Hughes, 2005). However, all four nitrogenous bases composing the inside of the structure are all nonpolar and therefore hydrophobic, meaning they are repelled by water (Hughes, 2005). This hydrophillic exterior and hydrophobic interior has a stabilizing effect on the entire double helix structure. The backbone works to protect the interior base pairings, keeping them in an ideal environment free from water. These forces keep the two strands together. Yet, what is important is understanding the fact that two strands of alternating sugar and phosphate groups enclose complementary base pairings among the nitrogenous bases. Human DNA contains approximately three billion of these bases, and more than 99% of those bases are the same in all people (National Library, 2008). Yet, within the remaining 1% there are 13 DNA genetic markers that reveal nucleotide sequences unique to that person (Budowle, Chakraborty, Carmody, & Monson, 2000).