DNA FINGERPRINTING

Deoxyribonucleic acid (DNA) in the Celleoxyribonucleic acid cell nucleus chromosome Double stranded DNA molecule

Double helix

The chemical structure of everyone's DNA is the same. The only difference between people (or any animal) is the order of the base pairs.base pairs Some regions- no genetic information -JUNK DNA vary enormously short sequence of DNA has been repeated a number of times- Variable number tandem repeats –VNTR/STR DNA Fingerprinting –used to distinguish individuals, method of identification that compares fragments of DNA called DNA typing. DNA Fingerprinting-Definition

Genetic continuity

Brief History of DNA Typing Watson & Crick described the structure of DNA (Nobel Prize) DNA fingerprinting developed by Alec Jeffreys Mullis developed protocol for polymerase chain reaction (PCR) (Nobel Prize)

Sources of DNA

STEPS IN DNA PROFILING Extraction of DNA DNA amplification by PCR Electrophoresis on Agarose gels Genetic analyser Analysis and interpretation of results

DNA is the choice for individual identification Discrimination/Distinguishing No two people except identical twins (monozygotic) will share the same genetic blueprint. Identical twins are essentially clones. Genetic Continuity The DNA found at birth in each of our cells will contain the same genetic blueprint that will be present in our cells at death. In addition genetic continuity extends across generations allowing family members to be identified through similar DNA genotypes. Sensitivity A few drops of blood, a buccal swab or a small semen stain will generally contain ample amounts of DNA for analysis. Stability The DNA molecule resembles a twisted ladder comprising three chemical components to form a phosphate-sugar backbone joined by rungs of organic bases (adenine, guanine, cytosine and thymine).

Real world applications  Which one matches? Food identification Crime scene Human remains Human relatedness Anthropology studies Disease-causing organisms Paternity Monitoring transplants Animal relatedness

Most Important cases solved by this technology  Fast track DNA analysis confirms the Saddam’s identity  Rajiv Gandhi assassination case –Elusive criminals like Sivarasan and 'Dhanu', have been tracked by DNA fingerprinting technique  Naina Sahni 'tandoor' murder, proved that the half charred remains were indeed of Naina

DNA is a powerful tool, both for conviction and EXONERATION of suspects.

We can use –DNA Fingerprinting DNA identifications after the 9/11 World Trade Center attack -this technique facilitated the identification of 1594 of the 2749 victims) Tsunami disaster – 2004

Size Mother Baby Father Hypothetical gel pattern for microsatellite heterozygous for all individuals. DNA fingerprint of Typical paternity case