Forensic DNA Testing Essay Example | Topics and Well Written Essays - 1250 words

Forensic deoxyribonucleic acid Testing - Essay ExampleThe DNA identification Act of 1994 formalized the FBIs authority to establish a National DNA Index System (NDIS). The CODIS is diametric from the NDIS in that NDIS is the national database whereas CODIS is utilise today by more than 40 law enforcement laboratories in everywhere 25 countries.( FBI, 2009) The CODIS system requires 4 RFLP markers and/or 13 core STR markers. Now, what be STRsMost of the DNA is indistinguishable to the DNA of others in the human genome. However, there are inherited regions of our DNA that may not needfully code for proteins termed as introns, which can divert from person to person. A variation in the DNA successiveness between individuals is termed as polymorphism. Sequences which display the highest degree of polymorphism are very useful for DNA analysis in forensics cases and paternity testing. Forensic DNA testing is based on analyzing the inheritance of a class of DNA polymorphisms known as Short Tandem Repeats or STRs. STRs are short periods of DNA, usually of length 2-5 base pairs, that are repeated numerous times in a head-tail manner, for example the sequence GATA occurs anywhere between 5-16 repeats at the locus D7S820. The number of repeats within an STR is referred to as an allele. Thus there are 12 different alleles possible for the D7S820 STR. Because there 12 different alleles for this STR, there are therefore 78 different possible genotypes, or pairs of alleles. Specifically, there are 12 homozygotes, in which the same allele is stock from each parent, as well as 66 heterozygotes, in which the two alleles are different. Norrgard,K.(2008) After an vast validation study, 13 STR loci were selected to form the core (i.e., required) genetic markers for CODIS. The methodology involved in the STR analysis is as follows. The DNA is isolated from the sample. The STR region in the DNA is amplified using PCR and suitable primers. The various companies manufacturi ng STR kits typically vary in the primer they employ. PCR enables even nanogram amounts of sample to be sufficient for evaluation. Only when all the 13 markers match in the source and the felon sample is the convict included in the source of crime. eve after all the 13STRs are matched a statistical test is carried out to analyze the overall STR frequency. It is fictitious that the STRs follow law of independent assortment which implies that each member of a pair of homologous chromosomes separates severally of the members of other pairs so the result is random and that the population mates randomly by the FBI in analyzing the STR profiles. The intrepid Weinberg law was used to calculate gene frequency which states that the gene frequencies remain conserved from generation to generation. It is grand to understand that this number is the probability of seeing this DNA profile if the crime scene evidence did not come from the suspect but from some other person. If all the STRs from the sample are not recoverable due to damaged or an extremely old source of DNA, then the STR profiling cannot be used as the sole evidence and other proofs have to be collected. Though the STR profiling is rapid the CODIS database is soon facing a backlog of 600,000 samples to be keyed in.In addition to