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Let me quickly paint a scenario for you. You were going out with a friend, but then you saw a man lying down and he has been stabbed. Just beside him is the knife. In a rush,  you were going to hold the man and grab the murder weapon so you can take him to the hospital but your friend quickly cautioned you and asked you to call the police and the ambulance first. When the local police arrived, they wore a glove and picked up the murder weapon, and your friend tells you that if you had touched the murder weapon, you would have implicated yourself with Genetic or DNA fingerprinting. So, what is genetic/DNA fingerprinting?

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The laboratory technique which is used to establish a biological evidence and a suspect link, and this is usually done in a criminal investigation. It is important to reiterate the biological link in the statement. So this means that if you had touched the murder weapon, you would have been linked to the stabing of the person on the ground according to the painted scenbario above. This technique was first discovered by Alec Jeffreys in 1984.

Every human have a 100% genome with 99.9% similarity in all humans but with a 0.1% difference. This is identified using Density gradient centrifugation which identifies the two peak. The 99.9% of DNA that is similar is known as the Bulk DNA, while the 0.1% of DNA that is different is the Satellite DNA, and as expected, the DNA that shows distinctive difference which is the Satellite DNA would be used in this technique. The DNA contains repititve patterns of nucleic acids which occur in numerous and repitive copies in the entire genome of humans. Satellite can be of two types which are minisatellites and the Microsatellites. Minisatellites are important as the can be used to determine the Variable Number of Tandem Repeats (VNTR's). Variable Number of Tandem Repeats is a location where short nucleotides are organized as tendom and this vary from one person to another. The basis of DNA fingerprint is based on repeated DNA sequence. VNTRs varies from 0.1 to 20KBp. Macrosatellite is termed as Short Sequence Repeat (SSR) which varies from 1 to 6Bps.

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The two different types are identified on three basis which are the **copy number** which is the number of time a sequence is repeated. Quickly, genetic materials includes Adenine, Guanine, Cytosine and Thymine (ATGC sequence). The second base is the **lenght of sequence** and the **Number of Purine and Pyrimidine**. 


To get a proper result, Polymorphism is introduced. To get the DNA fingerprint of any person, the steps include; **Isolate the DNA**, **Use of restriction endonucleases** enzyme, **seperation of the DNA sequences**, Transfer of imprint on **Nitrocellulose paper**, followed by the use of **Radiolabelled probe**, and confirm the binding through **autoradiography**. Let me quickly explain Polymerase Chain Reaction which is needed for the Genetic/DNA fingerprint. It is an invitro technique that requires the use of specific sequence of DNA, then amplify for further testing.

 In the case of a crime, a sample is taken from the suspects and the murder weapon where it will be undergo PCR where the DNA sample will be isolated, and the genetic information will be collected from all the chromosomes. Remember that DNA is made up of tiny nucleotide which determines the structure of proteins. The A,T,G, and C genetic material faces one another called complementary. The base sequence in VNTR is in a CTAGCC base repeated about 7 times while STR which is of the beases CA, repeated about 4 times. 

DNA fingerprinting can be used to identify a culprit in a crime scene, or to identify siblings and relatives. Similarities in the unique non-coding DNA region shows comfirmation for the DNA.

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<center>**Citation**</center>
https://le.ac.uk/dna-fingerprinting

https://www.nature.com/scitable/topicpage/forensics-dna-fingerprinting-and-codis-736/

https://www.yourgenome.org/facts/what-is-a-dna-fingerprint/

https://www.genome.gov/genetics-glossary/DNA-Fingerprinting

https://byjus.com/biology/dna-fingerprinting/

https://www.genome.gov/genetics-glossary/DNA-Sequencing