What does DNA profiling involve, and how is it used to compare DNA samples?

SouravNovember 8, 2024

Answer

DNA profiling, also known as DNA fingerprinting or genetic fingerprinting, is a forensic technique used to identify individuals based on their unique DNA characteristics. This process involves several key steps, including DNA extraction, amplification, and analysis, and is widely applied in criminal investigations, paternity testing, and genealogical research.

Steps Involved in DNA Profiling

1. Sample Collection: DNA can be extracted from various biological samples such as blood, saliva, hair, or skin cells. Even small amounts of DNA can be sufficient for profiling.
2. DNA Extraction: The DNA is isolated from the cells in the sample. Common methods include organic extraction (phenol-chloroform), Chelex extraction, and solid-phase extraction. The goal is to break down cell membranes and purify the DNA from other cellular components.
3. DNA Amplification: Due to the often limited amount of DNA available, polymerase chain reaction (PCR) is employed to amplify specific regions of the DNA known as short tandem repeats (STRs). These regions are highly variable among individuals and serve as key markers for identification.
4. Separation and Analysis: The amplified DNA fragments are then separated by size using gel electrophoresis or capillary electrophoresis. This process allows scientists to visualize the distinct patterns of STRs for comparison.
5. Comparison: The resulting DNA profiles are analyzed to determine matches between samples. If two samples originate from the same individual, their profiles will exhibit similar patterns at multiple STR loci.

Applications of DNA Profiling

• Criminal Investigations: Forensic scientists compare DNA profiles obtained from crime scenes with those of suspects. A match can provide strong evidence linking a suspect to a crime, while a lack of match can exonerate individuals.
• Paternity Testing: DNA profiling is commonly used to establish biological relationships, confirming or denying paternity through analysis of inherited STRs.
• Genealogical Research: Individuals use DNA profiling to trace ancestry and establish connections with relatives by comparing genetic markers across family members.
• Disaster Victim Identification: In cases of mass casualties, such as natural disasters or terrorist attacks, DNA profiling helps identify victims through biological samples collected from remains