Which of the following methods are commonly used in DNA finger printing?

PCR & RFLP

The correct answer is Option (2) -PCR & RFLP

DNA fingerprinting involves identifying differences in some specific regions in DNA sequence called as repetitive DNA, because in these sequences, a small stretch of DNA is repeated many times. These repetitive DNA are separated from bulk genomic DNA as different peaks during density gradient centrifugation. The bulk DNA forms a major peak and the other small peaks are referred to as satellite DNA.

Since DNA from every tissue (such as blood, hair-follicle, skin, bone, saliva, sperm etc.), from an individual show the same degree of polymorphism, they become very useful identification tool in forensic applications. Further, as the polymorphisms are inheritable from parents to children, DNA fingerprinting is the basis of paternity testing, in case of disputes.

The technique of DNA Fingerprinting was initially developed by Alec Jeffreys. He used a satellite DNA as probe that shows very high degree of polymorphism.

PCR can be used in DNA fingerprinting to generate numerous copies of isolated DNA, selectively amplifying a single copy of a desired sequence.

Restriction fragment length polymorphism (RFLP) is a method that reveals variation in DNA between individuals through the use of restriction enzymes. These enzymes cut DNA into fragments of varying lengths due to such variations. RFLP is used in forensic analysis and in the diagnosis of hereditary diseases.

The oldest method used in DNA fingerprinting studies is restriction fragment length polymorphism (RFLP) analysis. RFLP analysis has been widely employed by researchers to identify genes linked to several Mendelian (single-gene) diseases, such as Huntington's disease. This approach detects differences in DNA fragment lengths due to the presence or absence of a restriction enzyme site, or due to an insertion or deletion that occurs between two restriction enzyme sites. Although RFLP analysis does not require knowledge of the genome sequence.