DNA fingerprinting is a technicue of determining certain nucleotide sequences, generaly repeated sequences (Satellite DNA) in the human genome that produce a pattern of bands which is unique for every individua short nucleatide repeats in DNA called the Variable Number of Tandem Repeats or VNTRs that vary in number from persor
to person, but are inherited.
The basis of DNA fingerprinting are
Technique for DNA FingerprintingDNA fingerprints can be prepared from extremely minute amounts of blood, semen, hair bulb or any other cells of the bod, DNA s extracted from the celsin high-speed refr gerated centrifuge if the content o DNA is r ned it can be amplified by using.The major steps are as fo lows:
polymerase chain reaction. DNA is cut into fragments with restriction enzymes and subjected to restriction fragment length analysis. These DNA fragments are separated through gel electrophoresis. The separated fragments can be visualised by staining them with a dye that fluoresces under ultraviclet radiation. Double-stranded DNA, is then split into single-stranded DNA using alkaline chemicals. Separated DNA sequences are transferred from gel onto a nitrocellulose or nylon membrane (Southern blotting) The nylon sheet is then exposed to probes cr markers that are racicactive, synthetic DNA segments and complementary to known sequences. The probes target a specific nucleot de sequence, which is complementary to VNTR sequences and hybridise them, Lastly, X-ray flm is exposed to the nylon sheet containing radioactive probes. Dark bands develop at the probe bound DNA
sites. Thus, hybridised fragments are detected by autoradiography and the filrn developed represents DNA fingerprint Applications of DNA Fingerprintin Paternity Maternity disputes: For identifying the true (biolcgical father mother, DNA samples of the child, mother and father are taken. The bands of child's DNA should match the DNA prints of the biolcgical parents
Identification of the criminal: DNA fingerprints of suspects from blood or hair or semen picked up from the scene of cime are prepared and compared. The DNA fingerprint of the person matching the one cbtained from sample cbtained frcm the scene of crime can give a due to the actual criminal.
