Source: TH
Context: DNA polymorphisms and their role in DNA fingerprinting were highlighted for identifying individuals, exonerating the wrongly accused, and solving cold cases.
- Recent advancements show extraction of intact DNA from 65,000-year-old remains, proving DNA’s stability and forensic significance.
About DNA Polymorphism:
- What it is:
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- DNA polymorphism refers to the variations in DNA sequences among individuals that help in distinguishing one person from another.
- Key Features:
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- Arises due to mutations or variations in the DNA sequence.
- Found in both coding and non-coding regions of DNA.
- Occurs in forms like single nucleotide polymorphisms (SNPs) and short tandem repeats (STRs).
- How they differentiate between people:
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- Polymorphisms cause unique DNA patterns that differ in length or sequence.
- They help trace lineage and ancestry by identifying parental origin of chromosomes.
- Variation in repeat numbers at specific loci creates a distinct genetic profile.
About Short Tandem Repeats (STRs):
- What they are:
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- STRs are short sequences of DNA bases (2–6 base pairs) repeated multiple times in a row.
- Key Characteristics:
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- Found at specific locations in the genome.
- Highly polymorphic due to variation in repeat numbers among individuals.
- Serve as the basis for DNA fingerprinting.
About DNA Fingerprinting:
- What it is: A technique to create a unique DNA profile for an individual using STR patterns, helpful for identification and parentage analysis.
- Organs that can be used: Blood, Saliva, Semen, Skin cells, and Teeth and Bones.
- Key Features:
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- Utilizes PCR and capillary electrophoresis for amplification and separation of STRs.
- DNA fingerprints are unique for each person, except identical twins.
- Used for forensic investigations, disaster victim identification, and organ donor matching.
- Can analyze samples even from degraded or aged biological materials.
- Limitations:
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- Requires careful handling to avoid contamination.
- Partial profiles may arise from degraded samples.
- Cannot distinguish identical twins.
- Privacy concerns regarding genetic data misuse.
