DNA Fingerprint Explained
What distinguishes two individuals is the fact they have different DNA. Having different DNA in more specific terms would mean having different base pairs. This arises from the fact that each DNA has about 3 Million Base pairs and the chances of them recurring in two individuals is next to negligible. The fact that DNA sequences replicate or repeat itself allows scientists to drastically cut down on the time spent to 'identify a person' based on the DNA results. Rather than studying all the base pairs (which number close to 3 million), scientists study a set of DNA base pairs on the proven assumption that DNA base pairs repeat itself. So what do the scientists get at the end of this exercise. They do not get an individual fingerprint of the person, but scientists do get a good set of results which indicate if any two DNA samples belong to the same person or not. These results are used for probabilistic calculations to derive the exact match result out of the DNA analysis done.
DNA fingerprinting can be done in the following ways - · Performing a Southern Blot - This test is done by a step by step process of isolation of the DNA, 'cutting' of the DNA, sorting DNA pieces by size, Denaturing all the DNA, Blotting the DNA. At the end of all this, scientists get what they call as a Southern Blot and this Southern Blot is ready for analysis. · Hybridization Reaction - This works on the concept of binding of two genetic sequences due to hydrogen bonds between base pairs. There are four types of bases- A,T,C,G. The T base pairs up with A base forming an AT base pair whereas the C base does the same with G to form a CG base pairs. Detailed studies are carried out on these base pairs. · Radioactive probe - This is a highly technical activity where the DNA which needs to be subjected to radioactive energy is separated from DNA which will be preserved as is. · VNTR - VNTR stands for Variable Number Tandem Repeats. To understand the presence of a particular type of VNTR in an individual, first a Southern blot is performed after which it is probed through a hybridization reaction. The resultant pattern coming out of all these tests are known as DNA Fingerprints. Though DNA fingerprinting is of great use in determining the convict's role in a crime, it has found its use in forensic investigations too. In spite of the wide usage of DNA fingerprinting, there are some issues with Fingerprinting. Most of the problems are centered around the fact that a high probability of a DNA sample belonging to a certain person. This would mean that the forensic scientist should be able to have a lot of DNA samples to review and analyze and follow the scientific process to establish the DNA fingerprint of a person. |
