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How Does DNA Fingerprinting Identify a Person?

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The process through which a person is identified based on the analysis of his genetic material is referred to as DNA fingerprinting. The procedure is also known as genetic typing or DNA profiling. Identification of a person based on genetic material bases its analysis on the provided DNA and the person’s DNA. DNA fingerprinting is carried out in a laboratory where DNA is sampled from sources such as hair, blood and semen.

Specimen Collection

The process of identifying a person based on DNA material begins first by collecting DNA materials from several samples. The samples can vary, from the semen collected in a sex-related case or from other sources, such as hair and saliva. The sample should have white blood cells, which are usually opened up before a detergent is added. The detergent is usually added in order to separate the DNA material from the other cellular materials.


Forensic experts cut the DNA material into pieces using enzymes, which are known as restriction enzymes. The cutting is usually done following certain DNA sequences. Some of these sequences have blunt ends, while the others have sticky ends. Then, experts isolate small DNA fragments using electrophoresis gel. The gel disintegrates the DNA strands, making them single-stranded. This enables the DNA to release nucleotides so that they can be used in the DNA blotting process.

DNA Sequences

During the blotting process, the forensic experts are usually interested in finding certain molecules in the DNA fragments. The fragments are covered using a photographic film. The forensic experts probe for certain DNA sequences. They compare the different lengths of the DNA fragments with the DNA sample being used as the piece of evidence.

DNA Fingerprint

For DNA fingerprinting to be accurate, the forensic experts compare DNA samples from different sources. They then narrow down to the stretches of the repetitive DNA scattered in these samples. The profile of the repetitive regions in a particular DNA represents its fingerprint. Because no two people possess the same regions of repetitive DNA, the scientists use this to identify different people.

Importance of DNA

The importance of DNA fingerprinting lies in the fact that it is highly accurate. It is a good method to determine who was involved in a certain activity, such as rape, by comparing the DNA samples provided as exhibit. The method has been used to acquit innocent people who have been accused and sentenced to serve many years in US jails. In addition to determining who was involved in criminal activities, DNA fingerprinting is also used to determine family relations.

About the Author

Based in Kampala, Uganda, Ronny Kalyango has been writing since 2008. He has written for "Uganda Trends" magazine and "Daily Monitor" newspaper. He works as a features writer for Gulu Publishers, a news agency. Kalyango has a Bachelor of Arts in literature from Makerere University.