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What is DNA and How is it Used in Forensics?. Mrs. L. Fox. DNA is a Unique Identifier. The only ones that MIGHT be the same are identical twins * Chances of another person having the same DNA is 1 in a billion. An example. 4 Main Types of DNA Testing. RFLP
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What is DNA and How is it Used in Forensics? Mrs. L. Fox
DNA is a Unique Identifier • The only ones that MIGHT be the same are identical twins * • Chances of another person having the same DNA is 1 in a billion.
4 Main Types of DNA Testing • RFLP • The original testing process – but it needs large amounts of a sample. • PCR • Doesn’t actually type the DNA – it makes copies • Can be used with degraded DNA • Care must be taken to avoid contamination
DNA Testing • STR • Looks at shorter sections of DNA than RFLP • Often used to compare genetic evidence on the Y chromosome • Can be used with very small samples • mtDNA • Mitochondrial DNA • Used with hair and bones, which lack nucleated cells • Very old, degraded samples can use
How DNA Works • http://science.howstuffworks.com/life/genetic/dna-evidence.htm
Comparing DNA • http://www.pbs.org/wgbh/nova/education/body/create-dna-fingerprint.html
CODIS • Combined DNA Index System • Samples collected at state and local level • Profile is sent to national database
The Future of DNA in Forensics • Cost of processing is dropping • As more samples collected, matching is likelier • Still not foolproof – fraud is a possibility • Still time-consuming and expensive