dnalab - DNA Lab Write Up Jason Lim October 6 2010 Prior to...

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DNA Lab Write Up Jason Lim October 6, 2010
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Prior to present DNA techniques, DNA testing results took considerably longer to get. The first notable DNA testing was restricted fragment length polymorphism, or RFLP. When using RFLP, the British geneticist Alec Jeffreys classified several variable number tandem repeats (VNTR), a more “primitive” version of short tandem repeats that is being used currently. VNTR offered more variability among populations that other tests at the time, but because it was processed through RFLP, there had to be a significant amount of DNA to begin with (something that is usually not the case in investigations). STR testing used with PCR speeds up the process and also discriminates better than VNTR. For cases where there is a minimal amount of evidence, scientists have developed two methods for gathering and analyzing DNA: low copy number (LCN) and touch-DNA. LCN can be used to find DNA from a very small sample of five to twenty cells. The difference between LCN and touch-DNA is that Touch-DNA focuses on finding skin cells, and then amplifying the DNA using PCR. DNA in forensics is an excellent tool to convict the guilty and exonerate the innocent. Because DNA is unique amongst individuals (except for identical twins), the probability of a DNA sample being shared by more than one person is practically zero. The more loci positions scientists analyze, the better the probability of pinpointing who was at the crime scene grows exponentially. Aside from criminal investigations, DNA is also used to determine the paternity of a child, establish family ties, and determining whether someone carries a genetic defect. www.suite101.com/content/what-is-
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dnalab - DNA Lab Write Up Jason Lim October 6 2010 Prior to...

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