DNA Fingerprinting

DNA Fingerprinting: DNA fingerprints can establish parent/child relationships, help identify individuals from mortal remains at disaster sites, and exonerate wrongly accused convicts.

• Similar to Aadhaar for social security, DNA fingerprints uniquely identify individuals for biological purposes.
• About DNA: Each cell contains 46 DNA molecules — 23 from the father via sperm and 23 from the mother via the egg.

o Sperm and egg cells have only one copy of the genome each, unlike other cells.

o Chromosomes: DNA is packed inside chromosomes (e.g., chromosome no. 3 contains 6.5% of total DNA).

o Polymorphisms: Differences in DNA, called polymorphisms, help differentiate individuals and trace ancestry.

o STRs (Short Tandem Repeats): Repeated sequences of base-pairs in DNA, e.g., GATC-GATC-GATC. They are often polymorphic, making them ideal for DNA profiling.

• Applications of DNA Fingerprinting:

o Identification: Used to identify individuals from teeth, bones, blood, spit, semen, skin etc.

o Forensics: Identifies suspects from crime scene materials (blood stains, sweat, spit, etc.).

o Ancestry and Parentage: Establishes parent/child relationships and traces ancestry.

o Cold Cases: Solves old cases by re-analyzing DNA from archived crime scene materials.

o Exoneration: Has helped exonerate wrongly accused convicts.

o Organ Donation: Identifies/excludes potential donors.

o Stability: DNA is highly stable — recovered from 65,000-year-old human remains.