Southern Blotting: The Technique Used in DNA Fingerprinting

Correct Answer: (b) Southern Blotting

Southern Blotting in DNA Fingerprinting : DNA fingerprinting is a molecular technique used for identifying individuals based on unique DNA patterns. The correct technique used in DNA fingerprinting is Southern blotting, which detects specific DNA sequences.

Why Southern Blotting?

Southern blotting, developed by Edward M. Southern, allows the identification of specific DNA fragments within a mixture by using a radioactively or fluorescently labeled DNA probe. This technique is essential in DNA fingerprinting, where highly variable regions of DNA, such as VNTRs (Variable Number Tandem Repeats) and STRs (Short Tandem Repeats), are analyzed.

Why Other Options Are Incorrect?

• (a) Western Blotting – Used for protein detection, not DNA.
• (c) Northern Blotting – Detects RNA, not DNA.
• (d) Eastern Blotting – Primarily used for detecting post-translational modifications of proteins, not DNA.

Steps of Southern Blotting in DNA Fingerprinting

1. DNA Extraction – DNA is isolated from a biological sample (blood, hair, saliva).
2. Restriction Enzyme Digestion – DNA is cut into fragments using restriction enzymes.
3. Gel Electrophoresis – DNA fragments are separated by size using agarose gel electrophoresis.
4. Transfer to Membrane – DNA fragments are transferred onto a nylon or nitrocellulose membrane.
5. Hybridization with Probe – A radioactive or fluorescent-labeled DNA probe binds to the target DNA sequence.
6. Detection – The probe-bound DNA is visualized through autoradiography or chemiluminescence.

Applications of Southern Blotting in DNA Fingerprinting

• Forensic Science – Used for criminal investigations and solving crimes.
• Paternity Testing – Helps determine biological relationships.
• Genetic Studies – Used to identify genetic disorders and study hereditary diseases.
• Evolutionary Biology – Assists in studying genetic similarities and evolutionary relationships.

Conclusion

Southern blotting is the gold standard technique for DNA fingerprinting, making it an invaluable tool in forensic science, genetic testing, and evolutionary studies. Its ability to detect specific DNA sequences with high accuracy ensures its continued importance in molecular biology.

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