Dna Fingerprinting

DNA fingerprinting was discovered on September 10 1984 by Alec Jeffreys. His team at the university of Leicester had been working for seven years to see if it would be possible to tell people apart and whether they were related by using their DNA. They had been looking at regions of the human genome called VNTRs which stands for variable number tandem repeats. These can be thought of as a repeating string of genetic letters or basis, a bit like the same word written down many times along a line in this case the words are between 10 and 18 bases in length and the numbers of repeats the word can be as high as 30. You inherit these repeated sequences along with the rest of your DNA from your parents, but because the VNTRs occur within parts of the genome called non-coding regions that are actually used to encode …show more content…
After this breakthrough Jeffrey's lab was the only one to offer DNA fingerprinting and they were in high demand with cases from all over the world until the process was commercialized in 1987. Nowadays rather than VNTR's DNA fingerprinting makes use of sequences called short tandem repeats or STRs. These are similar to Jeffrey's VNT ours but a smaller and stand up better to the degradation of DNA over time which makes them much more useful for investigating crime scenes. An example of how DNA fingerprinting is carried out today the DNA from a sample such as a mouth swab, blood sample or a swab from a crime scene is extracted and purified in order to isolate the short tandem repeats. A procedure called Polymerase Chain Reaction (PCR) is carried out on the DNA. PCR copies or amplifies specific target DNA sequences. In this case the STR is targeted, increasing their relative numbers in the sample. The different lengths of STRs are copied by the PCR reaction then separated out using a process called