CRJS478IP3 - Research Paper Example

The focus of this process is on the short tandem repeats (STR) that have short units of DNA that are repeated several times in a row. After the DNA is isolated and amplified it is treated with restriction enzymes. The process cuts the DNA strands at definite sequences called restriction fragment length polymorphisms (RFLPs). Since everybody’s DNA is different the resulting RFLPs will be of different sizes. These fragments are observed in gel electrophoresis; a process that separates DNA based on the size of fragments (Brown, 2010).

RFLP analysis is based on the fact that since everyone’s genetic sequence or the variable number of tandem repeats is different this result in the different sizes of RFLPs. Gel electrophoresis involves separation of the fragments of DNA as they migrate through an agarose gel when an electric current is applied to the gel. The DNA that has separated is then drawn out of the gel with a nylon membrane which is treated to break the hydrogen bonds holding the DNA strands together. The separated strands of the DNA are then incubated using a radioactive probe and cross-linked to the nylon membrane of a strand comparable to the VNTRs.

The radioactive probe is visible on a photographic film as a dark spot is left on the film because of the light that is given off when the probe decays. Different people have different patterns and these constitute the fingerprints. This protocol of DNA fingerprinting is called Southern blotting (Brown, 2010). The main objective of DNA analysis is to obtain an observable representation of the DNA from the crime. The DNA profile obtained from DNA fingerprinting must match the DNA from the suspect or a profile in the DNA database.

The three possible results from comparing a DNA profile of the sample to the suspects DNA profile and it can either be inclusive, exclusive or inconclusive. Inclusions occur where the suspects DNA