Crime scene

Every strand of DNA is made up of exons (pieces that contain genetic information which informs an organism’s development) and introns (pieces that have no relevant genetic information at all). Despite the seemingly useless nature of the introns, they possess repeated sequences of base pairs. These sequences are known as VNTRs. VNTRs are composed of between 20 to 100 base pairs (Brinton and Lieberman, n. d. ). VNTRs are present in every human being. A Southern Blot is performed in order to find out if a VNTR belongs to a particular individual.

It is then probed through a hybridization reaction, along a radioactive version of the VNTR being analyzed. This process will bring about what is commonly known as a DNA fingerprint (Brinton and Lieberman, n. d. ). Controversies Surrounding DNA Fingerprinting Nowadays, DNA fingerprinting is often used in criminal identification and forensics. Guilt or innocence can be proven by taking a DNA sample from a criminal suspect and comparing its VNTR patterns with those of hair, skin cells, blood or other genetic evidence found in a crime scene.

The identity of a homicide victim can also be established VNTR patterns. Most states in the US have a fingerprint database wherein fingerprints of criminals are kept for future reference (Brinton and Lieberman, n. d. ). But DNA fingerprinting is not without controversy. Below are some of the issues it is confronting: Generating a High Probability In criminal cases, there must be a reasonably high probability that a DNA fingerprint belongs to a specific person. In order to come up with such a result, scientists must use either combinations of VNTRs or rare VNTRs.

Aside from the DNA of the suspect and or the victim, DNA samples from their relatives may also be analyzed for similarities. In doing so, the chance that the two DNA samples are correlated or matching is expected to increase (Brinton and Lieberman, n. d. ). Population Genetics Being results of genetic inheritance, VNTRs are not evenly distributed throughout racial groups. Some VNTRs may happen to be more dominant in certain ethnic groups than in others. Exclusively studying the genetic composition of a particular racial group can be interpreted as a revival of ethnic purification.

Some experts argue that it can likewise lead to racial discrimination (Brinton and Lieberman, n. d. ). Technical Difficulties The analysis of DNA fingerprinting in criminal cases leaves no room for human error. However, as in any scientific procedure, human error in processing DNA-based evidence is inevitable. This is dangerous, considering that even just one misstep in the procedure can produce false results. It would be very unfair for a guilty person to be set free or an innocent individual to be imprisoned simply because a lab technician committed a mistake in processing DNA taken from a crime scene (Brinton and Lieberman, n. d. ).

Conclusion DNA fingerprinting is one of the best innovations that were created in order to solve crime. DNA-based evidence is very reliable, considering that DNA is unique in every individual and can never be changed. But akin to any technology, it can only serve its intended purpose when used properly. Technology can magnify efficiency or inefficiency, depending on how it is used.


Brinton, K. & Lieberman, K. A. (n. d. ). Creating a Hybridization Reaction. Retrieved August 19, 2008, from http://protist. biology.washington. edu/fingerprint/hybrid. html Brinton, K. & Lieberman, K. A. (n. d. ). Making a Radioactive Probe. Retrieved August 19, 2008, from http://protist. biology. washington. edu/fingerprint/radi. html Brinton, K. & Lieberman, K. A. (n. d. ). Problems with DNA Fingerprinting. Retrieved August 19, 2008, from http://protist. biology. washington. edu/fingerprint/problems. html Brinton, K. & Lieberman, K. A. (n. d. ). Southern Blot. Retrieved August 19, 2008, from http://protist. biology. washington. edu/fingerprint/blot. html