GENOMIC TANDEM REPEATS AND DNA FINGERPRINTING
In the human genome, sequences of repeated nucleotides are repeated in tandem hundreds of times at dozens of different regions throughout ones genome. DNA profiling uses these numerous repetitive sequences as a method of identifying individuals. These repetitive sequences, called variable number tandem repeats (or VNTRs) and short tandem repeats (STRs) are highly variable and thus form excellent tools for genetic individualization.
CLASSES OF GENOMIC TANDEM REPEATS
An STR simply put is a short stretch of repeated units of DNA bases, usually comprising of 3-5 base pair segments that are repeated in long strings of DNA. As a result of their length, tiny samples can be easily analysed as they are amenable to amplification by …show more content…
VNTRs are also used in forensic analysis as VNTR loci are very similar between closely related humans. DNA fingerprinting involving VNTRs is based on the principle that each individual has a certain combination of alleles specific to their genome which can be used to identify them against a larger population.
PROCEDURE FOR DNA FINGERPRINTING
Individual-specific DNA identification is made possible because although those related share a certain combination of chromosomes, no two individuals are likely to have the same number of copies of these repetitive sequences.
In DNA fingerprinting, two DNA samples are gathered, for example, one from the scene of the crime and one from the suspect in question. Both these samples are treated with the same restriction enzyme which will cleave the DNA into 100,000’s of pieces. (EcoRI will cut at GAATTC; NotI at GCGGCCGC and AluI will cut DNA at AGCT). VNTRs will be present in these fragments of varying sizes. Electrophoresis is ran, and the DNA separates according to size. How far each strand migrates is indicative of its length. A technique called a Southern blot is then