Understand DNA Fingerprinting

DNA FINGERPRINTING

-DNA fingerprinting is also called as DNA profiling or DNA fingerprint.

-DNA fingerprinting method was developed by Alec Jeffery at the University of Leicester in 1984.

Any two persons are 99.99 percent same in terms of their DNA sequences; however, there is 0.01 percent difference. Human genome contains 3 billion base pairs. Less than 2 percent of the genome codes for proteins – rest 98 percent of the genome sequence is non-coding.  

The non coding regions have different regions such as STR (short tandem repeats), VNTR (variable number tandem repeats) and RFLP (Restriction Fragment Length Polymorphism), etc. 

If we take an example of three persons 1, 2 and 3 – their genes will be the same, but their tandem repeats (in this case, STRs) will be different. If we remove everything except STR sequences, we will get different fragments of variable sizes. 

If we use a specific DNA restriction enzyme to cut these STRs, we will get DNA molecules of different sizes. We can then separate them using gel electrophoresis.

Now, we can apply this DNA fingerprinting technique to catch a suspect in a murder case.  Let’s consider that the three individuals 1,2 and 3 as explained above are prime suspects of the murder. So, we can get the blood sample of every suspect as well as the victim and do fingerprinting.

From the above figure, we can conclude that the first person is guilty.