FSP 401 DNA Fingerprinting

Mode of Study -- Online/Distance
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    Course Outline

    DNA Fingerprinting, also termed as DNA Profiling, Genotyping, DNA Typing or Genetic Fingerprinting is one of the most recent advancements in Forensic Science. This technique was discovered by Sir. Alec Jeffreys in 1984. While going through this network, he noticed that certain sequences of highly variable DNA (known as minisatellites), do not contribute to the functions of genes, and are repeated within genes. Jeffreys recognized that each individual has a unique pattern of minisatellites (the only exceptions being multiple individuals from a single zygote, such as identical twins). For the extraction of DNA, a sample of cells such as skin, hair, blood, saliva etc. is required.

     

    According to this technique, the DNA is extracted from the cells of skin, hair, blood, saliva etc., and then it is purified. Jeffrey’s original approach was based on Restriction Fragment Length Polymorphism (RFLP). In the RFLP technology, the DNA was cut at specific points along the strand with proteins known as restriction enzymes. The enzymes produced fragments of varying lengths that were sorted by placing them on a gel and then subjecting the gel to an electric current (electrophoresis): the shorter the fragment, the more quickly it moved toward the positive pole (anode). The sorted double-stranded DNA fragments were then subjected to a blotting technique in which they were split into single strands and transferred to a nylon sheet. The fragments underwent autoradiography in which they were exposed to DNA probes—pieces of synthetic DNA that were made radioactive and that bound to the minisatellites. A piece of X-ray film was then exposed to the fragments, and a dark mark was produced at any point where a radioactive probe had become attached. The resultant pattern of marks could then be analyzed. Other than RFLP, Polymerase Chain Reaction (PCR), Short Tandem Repeats (STR) and Variable Number Tandem Repeats are also used for the analysis procedure.

     

    DNA Fingerprinting technique is used in cases of sexual assaults, missing persons, paternity-maternity issues and certain other criminal cases. This course structure would make the students aware of the complex techniques and analytical methods employed by the scientists in DNA Profiling, and the revolution that the discovery of DNA Fingerprinting brought into the criminal investigation system.