DNA Polymorphism

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:

• DNA polymorphism refers to the variations in DNA sequences among individuals that help in distinguishing one person from another.

• Key Features:

• 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).

• 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:

• 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.

• 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:

• STRs are short sequences of DNA bases (2–6 base pairs) repeated multiple times in a row.

• Key Characteristics:

• Found at specific locations in the genome. Highly polymorphic due to variation in repeat numbers among individuals. Serve as the basis for DNA fingerprinting.

• 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:

• 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.

• 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:

• Requires careful handling to avoid contamination. Partial profiles may arise from degraded samples. Cannot distinguish identical twins. Privacy concerns regarding genetic data misuse.

• Requires careful handling to avoid contamination.

• Partial profiles may arise from degraded samples.

• Cannot distinguish identical twins.

• Privacy concerns regarding genetic data misuse.