DNA Fingerprinting Process

Human DNA is similar in almost all its aspects with regards to its chemical components or framework. The DNA or deoxyribonucleic acid structure consists of base pairs of nucleotides, which occupy either ends of a DNA strand. Each animal or species has millions of such base pairs in their makeup. The sequence in which these pairs appear is not uniform and varies with every case being considered. This is what imparts the uniqueness to every human DNA structure. The process of analyzing or comparing these sequences is referred to as DNA fingerprinting, DNA profiling or DNA typing. Although, it is practically impossible to track all the base pair patterns (as it would take a lot of time), the repetition sequence of a part is used in DNA fingerprinting. The DNA fingerprinting process is complex and is done at special certified labs only.

The science of DNA sequencing has developed a lot since the first profiling was done in the year 1985 by Sir Alec Jeffreys in England. There were many DNA research activities undertaken earlier to understand exactly what the process of DNA fingerprinting was. Since Sir Jeffery's discovery at the University of Leicester, human genetic science has made great strides in identification of unique DNA patterns.

How Does DNA Fingerprinting Work: A Brief Perspective

In a testing lab, several enzymes are employed for the purpose of cutting out a sample of DNA sequence from the subject. These samples are segregated according to their size and are marked with a special radioactive probing mechanism. The samples are sensitive to X-rays and hence can be detected on the X-ray photographs. The resulting pattern consists of black colored lines, each representing a particular DNA sequence. This is how a DNA fingerprint is obtained.

The sample is collected from the subject in the form of a specimen of hair, saliva, sperm, a buccal swab or any fluid tissue sample from one of the body parts. A DNA sequence is in the form of paired helix strands. These strands are separated using a variety of techniques. A particular sequence is cut by one particular enzyme. On completion of this stage, the entire sequence is cut of into free and individual strands, collected together.

The next logical process that follows is sorting of the DNA sequences. Here again, there are methods like electrophoresis gel application used for organizing the sequence. DNA being charged particles, get affected by the application of positive and negative charges. An electric field application around it, produces an affinity towards one of the electrodes. However, the smaller molecules move faster and hence are more closer to the electrode than the larger ones. This separates the various sequences of different sizes.

The next stage is obtaining images of these sequences. For this purpose, another set of radioactive enzymes is added to the sequences. These gels stick to the different categories of the strands and become visible on exposure to photographic film. Sometimes, chemiluminescence, a process where chemicals emit light by a chemical reaction, is used in the process.

The above processes are repeated several times, until a detailed classification is obtained and hence distinguishing between various elements and their study is possible. The inter-mediate stages can vary in methods or chemicals used, but the principle remains mostly the same. Thus, the DNA fingerprinting process is complete. In order to understand what is the process of DNA fingerprinting in detail, a certified laboratory can be approached, where DNA testing is carried out.