Uses Of Dna And Fingerprints In Crime Scene Investigation

1212 words - 5 pages

What is Forensics? Forensics is the application of science to solving crimes. Forensics pertains mostly to DNA and the use of fingerprints. DNA is Deoxyribonucleic Acid and can be collected from blood, hair, skin, saliva, sperm, dandruff and even bones. Bones can be analyzed to tell approximately how old the person was. DNA is known as the molecular "fingerprint". No two people (except identical twins) have the same DNA. Determining the DNA from the objects takes from thirty-six hours to three weeks using a five-step process.Step one is known as Isolation. DNA is removed from the nucleus of cells found in skin, blood, sperm, spit and other bodily from a human body. The quality of the DNA decreases as the body decomposes. When skin, blood, and other bodily fluids are not available, mitochondrial tests are taken using samples of hair, dandruff and bone. The Nuclear test is a lot quicker than the mitochondrial test. DNA is "washed" using chemicals to remove unwanted cellular materials. These tests may take from one to four hours depending on the type of sample given and the age and quality of the sample used.The second step is known as Quantifying. Forensic scientists run tests to find how many recovered DNA are present. Guesses are made by comparing standard DNA amounts to amount collected by step number one. The minimum amount of DNA needed is one nanogram (one billionth of a gram) for the test. This step takes about one to two hours.The third step is known as Polymerase Chain Reaction (PCR). Certain chemicals are added to make specific parts of DNA reproduce Millions of times. Thirteen specific locations are used for examination in machine that has heating and cooling cycles needed to be run to be able for the DNA to be used to run against other DNA. Polymerase Chain Reaction takes approximately three to five hours.Step four is known as Typing. A machine called a Genetic Analyzer takes images of DNA as it moves around and through the test tube containing the DNA. The results are shown as spikes or peaks like shown on an EKG (electrocardiogram) machine. A 3D electronic picture is created and is represented as numbers and compared to standard DNA image. Typing takes about twenty to thirty minutes.Step five is known as Interpretation. The DNA profile is reviewed by forensic scientists to determine a match or non-match. A match would mean that DNA was contributed by a certain person. A non-match would mean the individual person didn't contribute the DNA. Also if a non-match is close to the sample given it indicates a direct blood line indicating that they are related to the person in which narrows the field drastically. Interpretation takes about one to three hours depending on the quality of the samples given.DNA is a relatively new concept to forensic science, since it has only been used for about 30 years. Scientists compare at least two strands of DNA, one is a sample from a crime or missing person case and the others are the DNA of a suspects or...

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