DNA FINGERPRINTING
Jan 04, 2016
DNA FINGERPRINTING
Deoxyribonucleic acid (DNA) in the Cell
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.
•Some regions- no genetic information -JUNK DNAvary 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 TypingBrief History of DNA Typing
1954 - Watson & Crick described the structure of DNA (Nobel Prize)
1984- DNA fingerprinting developed by Alec Jeffreys
1985 - 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 studiesD
isease-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 FatherHypothetical gel patternfor microsatellite heterozygousfor all individuals.
DNA fingerprint of Typical paternity case