Short Tandem Repeat (STR) Essay Example | Topics and Well Written Essays - 1250 words

Short Tandem absorb (STR) - Essay ExampleBecause of their varying repeat lengths, STRs are characterized with large number of alleles, which in turn start them being highly variable between populations (Lee et al, 1994). In addition, these microsatellite sequences account approximately for 3 percent of the compassionate genome and occur on average every 10,000 nucleotides (Collins et al, 2003). Finally, among other types of biological material, STRs are characterized with consistency and stability, which practically center that any cell contains the very same profile of SRTs. From the forensic perspective, it means that regardless of type of biological material obtained in the crime scene, appropriate STR profile proving source attribution can be conducted use any type of cell without compromising the result.From the practical perspective, STR profile constitutes simply a panel of numeric designations of each STR allele repeat number based on their electrophoretic sizing informa tion. The electrophoretic mobility of deoxyribonucleic acid is inversely proportional to the length of the fragment the longer allele with more repeats migrates slower than the shorter alleles containing fewer repeats. If a snapshot (electropherogram) is taken at a time point when two alleles of different lengths are electrophoretically migrating through and through a gel, the shorter allele will appear further from the origin than the longer allele. When looking at multiple alleles simultaneously, the STR electropherogram pattern (profile) of an individual is different from that of another individual whose alleles may be longer or shorter and indeed assigned with different allele numbers. The variation in STR allele sizes results in distinctive DNA profiles with a drollness of 1 in a trillion using the 13 core STR loci in the FBIs national database known as COmbined DNA Index System (CODIS). These 13 loci were chosen for their unique characteristics, such as number of alleles an d repeat sequence, present in each one of them. Their adoption in the