DNA Fingerprinting: Definition, Steps involved and Applications
As fingerprints have proved useful for identification of individuals to fairly good extent, DNA of an individual distinguishes her or him more exactly from others and using DNA for distinguishing and identification is DNA fingerprinting.
DNA Fingerprinting or DNA Profiling
DNA fingerprinting is a quick way to compare the DNA sequences of any two individuals. It is also known as DNA Profiling
Dr. Alec Jeffreys developed the technique of DNA fingerprinting in an attempt to called as repetitive DNA. The repetitive DNAs are separated from bulk genomic DNA as different peaks during density gradient centrifugation. The bulk DNA forms a major peak and the the other small peaks are referred as satellite DNA.
Satellite DNA can be classified as micro satellites, mini satellites etc., bases on the length of segment and number of repetitive units. these sequences show high degree of polymorphism and form the basis of DNA fingerprinting.
Applications of DNA Fingerprinting
1.To settle disputed parentage: It is the basis of paternity testing in case of disputes.
2. In forensic science: It is useful as identification tool in forensic applications.
DNA fingerprinting Multiple Choice Quiz
3.Diagnosis of Inherited Disorders: Diagnose inherited disorders in both prenatal and newborn babies.These disorders may include Huntington's disease, familial Alzheimer's, sickle cell anemia, thalassemia, cystic fibrosis (CF) and hemophilia.
4. Developing Cures for Inherited Disorders By studying the DNA fingerprints of relatives who have a history of some particular disorder
5. To confirm cell line identity in a cell line collection.
6. To assess migration pattern of ancient populations.
7. In evolutionary biology: It is used in determining population and genetic diversities and also in evolutionary biology. Pedigree analysis in man, dog, cat etc
DNA Fingerprinting Steps Involved
- Biotechnology and Bioinformatics Notes
Notes on Recombinant DNA technology (Gene cloning vector, Genomic and cDNA library) and Molecular Biology Techniques: PCR, Blotting Techniques, DNA footprinting, RFLP and RAPD.
Methodology of DNA Fingerprinting
1. Extract and purify DNA from cells (A drop of blood or semen or a piece of hair root or any tissues can be used to isolate DNA.)
2. DNA is digested or restricted with enzymes (restriction endonucleases) without causing cut in the minisatellite region
3. DNA fragments are separated by electrophoresis
4. Denature DNA
5. Separated DNA fragments are transferred to synthetic membranes like nitrocellulase or nylon.
6. Add labelled VNTR* probe for hybridization to take place
7. Wash off unbound probe
8. Hybridised DNA fragments are detected by autoradiography.
VNTR - Variable Number of Tandem Repeats or Mini Satellite