The Impact of genetic fingerprinting and gene profiling in Forensic Science

Authors Avatar

Helen Douglas 12.4

BIOLOGY COURSEWORK:

The Impact of genetic fingerprinting and gene profiling in Forensic Science

        Gene profiling and genetic fingerprinting was unheard of in Forensic Science 20 years ago.  DNA testing was initially introduced in the 1980s and the first court case, which saw a man put behind bars due to the forensic evidence was in 1985.  Following the success of the use of physical proof, numerous cases around the world from paternity tests to identification of American soldiers from the Vietnam War have been solved.

        A person’s DNA (de-oxyribonucleic acid) can be found from a single strand of hair, skin under a murder victim’s nails or bodily fluids such as sweat, saliva, semen and blood. The chances of a sample of DNA being the same as another person, other than monozygotic twins is 1 in 24 million. This is why recent cases such as that of Sarah Payne rely so much on DNA samples found at the crime scene. In this case a single strand of Sarah’s hair was found on Roy Whitting’s sweatshirt and matching fibres from his sweatshirt were found on her shoe, although there was slight controversy as to whether the evidence was contaminated.

         The method for extracting the DNA from a sample is a complex one.  The technique was first developed in this country in 1985, the year of the first proven case. Firstly the DNA must be extracted from the sample of body tissue or fluid. This could be a very small amount in a criminal investigation where the offender could’ve taken every precaution to avoid being caught.  A process called Polymerase Chain Reaction (PCR) then multiplies the sample and produces millions of identical strands of DNA.  PCR is completed by a “repetitious, cyclic programme of heating and cooling the substance together with a heat resistant DNA polymerase and two specific DNA primers. The polymerase and primers reproduce a small region of a genome, the whole of the DNA of the organism.” – quoted from DNA in Forensic Science by J. Robertson, A.M. Ross and L.A. Burgoyne.

Join now!

Forensic scientists use PCR to produce plenty of DNA to carry out all the necessary experiments to obtain a conclusive result.  The DNA is then broken up, using enzymes, into standard fragments. The enzymes used cut the DNA at precise sequences of A C G and T in the DNA.  A few fragments are then chosen and separated by size on a gel. The gel is then exposed to radioactive samples of the DNA. This produces different sized bands and the bands that have the same sequence of DNA are prominent. Generally the DNA evidence found at the scene is ...

This is a preview of the whole essay