Which of the following methods are commonly used in DNA finger printi…

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

DNA fingerprinting compares the repetitive DNA (VNTRs) of individuals. The DNA is cut by restriction enzymes, and the different fragment lengths give a band pattern; this length variation is a restriction fragment length polymorphism (RFLP).

Option (1) genetic transformation — Incorrect. Transformation is the uptake of foreign DNA by a cell, as in Griffith’s experiment or making competent bacteria.

Option (2) PCR & RFLP — Correct. PCR (polymerase chain reaction) amplifies the DNA, so that DNA from a single cell is enough; restriction digestion gives the RFLP (restriction fragment length polymorphism) band pattern that is compared.

Option (3) bio prospecting — Incorrect. Bioprospecting is the search for useful products in biological resources.

Option (4) molecular diagnosis — Incorrect. Molecular diagnosis is the early detection of disease using PCR or ELISA; it is a use of these tools, not the method of fingerprinting.

NCERT Extract:
DNA Fingerprinting – “… The numbers of repeat show very high degree of polymorphism. As a result the size of VNTR varies in size from 0.1 to 20 kb. Consequently, after hybridisation with VNTR probe, the autoradiogram gives many bands of differing sizes. These bands give a characteristic pattern for an individual DNA (Figure 5.16). It differs from individual to individual in a population except in the case of monozygotic (identical) twins. The sensitivity of the technique has been increased by use of polymerase chain reaction (PCR– you will study about it in Chapter 9). Consequently, DNA from a single cell is enough to perform DNA fingerprinting analysis.”

Figure 5.16 Schematic representation of DNA fingerprinting : Few representative chromosomes have been shown to contain different copy number of VNTR. For the sake of understanding different colour schemes have been used to trace the origin of each band in the gel. The two alleles (paternal and maternal) of a chromosome also contain different copy numbers of VNTR. It is clear that the banding pattern of DNA from crime scene matches with individual B, and not with A