Molecular Biology's Role In Forensic Science

People these days have become more and more familiar with forensic science. We may not recognize that we see it frequently on television, either on the news or on television drama. This discipline is an applied science that branched out from genetics and molecular biology. Forensic science has been developed to a great length since its first discovery in 1980s and up until today it is still being improved. It has been widely used to solve various criminal cases on court. Crime investigations, paternity cases, and many other lawsuits rely heavily on forensic science [1].

The objective of this discussion is to give a better understanding of how molecular biology aid forensic science, notably during lab-analysis, to resolve various criminal and

Our DNA is consisted of coding and non-coding regions. Coding regions contain information to produce various proteins, whereas non-coding regions do not contain any valid information. Within a family, children could have same coding regions to their mother, father or to their siblings. However, the non-coding regions would be different and remarkably polymorphic which means the sequence, the length, and number of repetition of particular region are different among individuals. The non-coding sequence commonly organized into repeated stretches called Variable Number of Tandem Repeats (VNTR). Figure 1 illustrates VNTR (the pink boxes) [4]. Because VNTR are polymorphic, it is used for forensic analysis. VNTR analysis procedure is approximately the same as RFLP, only the restriction enzymes are targeting the defined VNTR regions [3].

Some disadvantages using RFLP and VNTR methods are the need of un-degraded DNA and high amount of DNA samples. Forensic scientists do not always come to meet the requirements from crime scenes. However, along with the advancement of technology, new machines and procedures are constantly being produced to help develop molecular biology analysis, including forensic science

Each individual would produce distinctive pattern of bands based on the specific lengths of their DNA fragments. Figure 3 illustrates STR autoradiograph [7]. Lane 1 act as ladder or marker (both far left). The ladder or marker is consisted of ladders of defined lengths of DNA which then provides information of the length of our DNA samples by comparing its position to the ladder. The 5 lanes, accented with bold colors, show variation within STR from 5 individuals. Each lane represents a single person. 5 different individuals would have different composition in their DNA, this result in different lengths of STR fragments produced and consequently different rate migration [3].

Here is an example of how DNA profiling is used in forensics. Figure 4 shows another autoradiograph taken from a rape case [8]. As seen from Figure 4, there are 9 lanes being displayed. Lane 1, 5, and 9 are markers. Lane 2 and 4 contain DNA obtained from blood samples of each suspects (suspect A and B). Lane 3 and 6 contain DNA obtained from semen on woman’s clothing and by swabbing on vaginal canal. Lane 8 contains control