Implications of DNA Fingerprinting - Essay Example

Four Nucleotide bases pair with each other in a unique manner i.e. Adenine-Thymine and Guanine-Cytosine to form the unique DNA structure of every living thing. These bases are also attached to a sugar backbone that twists and turns in a double helix manner and gives the molecule of its shape (Crocket 2001).

Implications

DNA fingerprinting, as the name implies is a technique used for identification in many fields of science. Since fingerprints of not two individuals are similar, it has been proved that just like fingerprints, the DNA sequence of every individual is also different and the identity of a person in many cases can be found by using this technique. Although many moral and ethical issues have been raised on the use of this technique it is very helpful in identifying individuals in many cases where it was almost impossible to attain a hundred percent identity mainly because only the remains of individuals were found or in mass disasters where the bodies were destroyed that obtaining fingerprints was almost impossible. For example in a mass disaster, the DNA samples of the relatives i.e. parents,  siblings, or offspring of the victims are taken and then the DNA sequence is matched with that of the victims, and identities are generated based on the matching of base pairs. Also, DNA fingerprints have been used in solving cases of disputed paternity, identifying a rapist in cases of sexual assault, and identifying the species in cases of fragmentary remains.

Types and Techniques:

            The three main types of DNA Fingerprinting are:

• RFLP (Restriction Fragment Length Polymorphism)
• VNTR (Variable Number Tandem Repeats)
• STR ( Short Tandem Repeats)

RFLPs are the oldest type of DNA fingerprints. For this process, a sample from any part of the body is collected since all the nucleated cells of the body contain DNA. After the sample is collected, DNA is extracted from the sample by using restriction enzymes(Crocket 2001). Restriction enzymes are highly specific enzymes for specific sequences of DNA and they act on and cleave only the sequences they are programmed for.  After the DNA samples are properly extracted, specific band patterns are generated in agarose gel by using the process of Electrophoresis. This is a process in which an electric current is applied to each side of the sheet containing the extracted DNA on a sheet and movement of particles is observed which creates a band pattern (Burke 1991). This banding pattern is then recorded on a nylon sheet by placing it over the agarose gel containing the original pattern and RFLPs are obtained by probing them either with a fluorescent material or radioactive material.

The Second type of DNA fingerprint is VNTR. They appear as 9-80 base repeats on specific regions of chromosomes. For the purpose to generate DNA fingerprints of an individual of this type, four steps are required

• Southern Blot technique (To extract DNA from the nucleus)
• Radioactive Probe making process (For fluorescence)
• Performing hybridization Reaction
• Finding the VNTRs (Variable Number of Tandem Repeats) (Molecular Biology and Genetic Engineering 2009)

This process is almost the same as that for RFLPs. However exact process could also be used to find VNTRs.

Another and the most modern and technologically advanced process to generate DNA fingerprints is STR i.e. Short Tandem Repeats and PCR i.e. Polymerase Chain Reaction. This technique has revolutionized the world of forensic sciences as the generation of DNA fingerprints and the identification process is much quicker and easier now. This technique generates smaller base repeats i.e.2-5 that are easy to be analyzed by PCR. The PCR technique is used mainly for amplification. For this purpose, three necessary things required are: 1) A priming sequence, 2) TAQ Polymerase, and 3) a solution of 4 DNA bases (Burke 1991). All these things are mixed in the test tube along with the sample to be analyzed and then they go through a cycle of three main steps i.e.

1. Breaking the double helix (Unzipping) by heating to 95 degrees.
2. Allowing the solution to cool back till it reaches the temperature of 55 degrees so that primers could bind to the target DNA i.e. the sample.
3. Reheating the solution till it reaches the optimum temperature for TAQ polymerase i.e. 75 degrees.

This process completes in about 2 minutes. The cycle is repeated again and again till the required amount of amplification is reached which is usually 50 cycles equivalent to 25 times amplification (Burke 1991).

So far, STR and PCR have been the most famous types of DNA fingerprints. As compared to the complicated process of generating fingerprints by using RFLP and VNTR, the process of STR and PCR is less complex and time-consuming i.e. it takes only a few hours as compared to days taken by the latter two. Also, it avoids the hybridization process which again helps avoid much hassle.