DNA Polymorphism & Fingerprinting

DNA Polymorphism & Fingerprinting Latest News

Last DNA match day occurred after the family held a symbolic funeral for the victims of Air India Flight AI 171, which crashed on June 12, 2025, resulting in the tragic death of 241 people.

What is DNA?

• DNA (Deoxyribonucleic Acid) is the hereditary material found in almost all human cells – blood, skin, bone, teeth, etc.
• Humans have 46 chromosomes:
  • 23 inherited from the father (via sperm)
  • 23 inherited from the mother (via egg)
• Genes within chromosomes determine physical traits and biological identity.

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DNA Polymorphisms

• DNA polymorphisms are variations in DNA sequences unique to individuals.
• Useful for:
  • Parentage identification
  • Genetic lineage tracing
  • Identity verification in forensic science
• Enable accurate matching between body samples and known relatives.

Short Tandem Repeats (STRs)

• STRs are short, repeating sequences of DNA bases (e.g., GATCGATC).
• Each individual has a unique STR pattern, making them ideal for:
  • Criminal investigations
  • Forensic victim identification
  • Ancestry and paternity testing
• STRs are inherited, providing strong evidence for genetic relationships.

PCR (Polymerase Chain Reaction) in DNA Amplification

• PCR is a technique to amplify small amounts of DNA for analysis.
• Steps involved:
  • DNA Extraction from bones, blood, or tissue
  • Denaturation (95°C): DNA strands are separated
  • Annealing (60°C): Primers bind to specific DNA sequences
  • Extension (72°C): DNA polymerase builds new strands
  • Cycling: Steps are repeated to create millions of DNA copies

DNA Fingerprinting

• A DNA fingerprinting is a unique genetic profile built using STR variations.
• Capillary Electrophoresis separates STR fragments based on size using electric current.
• Final output is a distinct DNA profile, unique to each person (except identical twins).
• Sources for DNA: blood, saliva, bone, teeth, skin cells, sweat, semen.

Source: IE