ngerprinting used in criminal justice: it exonerated one person and convicted an
ID: 267070 • Letter: N
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ngerprinting used in criminal justice: it exonerated one person and convicted another. In 1984 Dr. Alec Jeffreys determined a way to analyze human DNA and create a "DNA fingerprint. "Specifically, he noticed that there are regions of base pairs within the human genome that are highly repetitive (the same sequence of bases repeated over a each person. It was this varying number of repeated sequences that he found to be an extremely unique identifier for an individual and referred to it as that person's DNA fingerprint (Gust like your actual fingerprint identifies you). This technique has several applications including crime scene forensic science, identification of remains, and paternity suits. The rest of thelab will focus on this technique as applied to criminal forensic science. The first step is to obtain DNA from the crime scene. It would be difficult for a criminal to ensure that no DNA was left behind since it would be a part of almost any cell from his/her body nd over) and unique to 1. Explain why almost any cell on your body could "give a person away" if found at a crime scene. Once the DNA has been collected from any number of sources, including blood, semen, skin, and hair, it will be "digested" by restriction enzymes. These are enzymes that were originally isolated from bacteria that recognize a specific sequence of bases and cut the D one of those sequences. For example, the restriction enzyme HaellI was NA at each terium Haemophilus aegypticus and recognizes the following sequence: 5'GGCC3. If a sample of DNA was mixed with Haelll, it would result in what is referred to as "digested DNA" and your resulting DNA will be in smaller fragments. The size of the fragments will be determined by where the recognition sequence was and how many times it was present. See Figure 8.1. Restriction enzymes can create two kinds of cuts in DNA. One type of cut creates what is known as "blunt ends"; this is where the restriction enzyme cuts straight across the double helix. The second type of restriction enzyme will cut across the helix in an offset fashion creating what are referred to as "sticky ends." These so-called sticky ends are just pieces of DNA with a short single-stranded end where the cut was made. EcoRI is a well-known restriction enzyme that produces these kinds of cuts and it recognizes the sequence 5'GAATTC3'. See Figure 8.2. 2. What would be the point of "digesting" two different sources of DNA with a restriction enzyme that produces "sticky ends"? Assume that both sources of DNA are cut with the same restriction enzyme.Explanation / Answer
Ans 1) Any cell in the body could “give a person away” if found at a crime scene because all the cells of that person will contain the same DNA fingerprint which is unique to the individuals. The construction and DNA element of all the cells is same and hence fingerprinting can be done using any type of cell. It helps in genetically identifying the person. Each of the cells will show the highly repetitive sequence that is unique to each person.
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