Research Focus

DNA Fingerprinting Research 


In 1984, Alec Jeffreys a British geneticist developed the method for isolating and making images of sequences of DNA.

In his research, he determined that first to obtain samples of DNA you extract the DNA and purify it. Then enzymes cut the DNA and fragments are formed.  The fragments of varying lengths undergo procedures that permit the fragments to be analyzed.  It has been found, that each individual has a unique pattern of fragments.

DNA fingerprinting is used for many things such as helping solve crimes and to determine paternity. Additional studies have also found that genetic diseases can also be located through gene segments. 

There are two different DNA tests, the RFLP and the PCR. Both are very accurate in determining a person's identification, but they are conducted in different ways.


PCR - Polymerase Chain Reaction

  • Only a small sample is required 
  • Small amounts of DNA is copied many times by the polymerases force
  • When needed, older samples can be used 
  • PCR only analyzes a specific gene, matches are found after genes are analyzed
  • If no match is able to be found, PCR determines that the donor was not at the scenes.  However, a match doesn't prove conclusively the person was there since many people may have the same match
  • The PCR takes less time and is less costly than the RFLP, but is not as accurate  

RFLP - Restriction Fragment Length Polymorphism

  • A large sample of fresh DNA is required
  • The RFLP process takes longer to analysis than the PCR process 
  • If a match is found, the sample accurately detects that the suspect was at the scene
  • RFLP has been found to be more accurate than PCR

With both PCR and RFLP require a second technique called Southern Blotting is required.  This process separates fragments of DNA and represents them as bands.


Edward M. Southern developed the Southern blotting procedure at Edinburgh University in the 1970s. To simply the process, DNA molecules are transferred from an agarose gel onto a membrane.

The same procedure works on RNA, but instead of Southern Blotting, the process is called Northern Blotting.




C. Davis©2007


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