DNA tests are performed by analyzing biological samples, most commonly blood or cheek swabs, to identify and compare an individual's unique genetic markers.
Methods of DNA Testing
Several methods exist for DNA testing, each with its own advantages and applications. The two most common methods involving blood and cheek swabs are described below:
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Blood Tests (RFLP Analysis):
- A blood sample is collected from the individual.
- The DNA is extracted from the blood cells.
- Restriction Fragment Length Polymorphism (RFLP) is a technique that was previously commonly used (though now less so due to newer, faster methods). It involves cutting the DNA into fragments using restriction enzymes.
- These DNA fragments are separated based on size using gel electrophoresis.
- The resulting pattern of fragments is compared between the individual being tested (e.g., a potential father) and a reference sample (e.g., the child). Matching patterns indicate a genetic relationship.
- RFLP requires a relatively large amount of DNA, and the process can be time-consuming.
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Cheek Swab (Buccal Swab) Analysis:
- A sterile cotton swab is used to gently collect cells from the inside of the cheek.
- The swab is then sent to a laboratory for analysis.
- DNA is extracted from the collected cells.
- Polymerase Chain Reaction (PCR) is often used to amplify specific regions of the DNA, allowing for analysis even with a small sample.
- Short Tandem Repeat (STR) analysis is a common method. STRs are short, repeating sequences of DNA that vary in length between individuals. The number of repeats at specific locations (loci) on the chromosomes are determined.
- The STR profiles are then compared to determine the likelihood of a genetic match.
- Cheek swabs are a non-invasive and convenient method for collecting DNA samples.
Common DNA Testing Applications
- Paternity Testing: Determining the biological father of a child.
- Ancestry Testing: Tracing family history and geographic origins.
- Forensic Science: Identifying suspects in criminal investigations.
- Medical Diagnostics: Screening for genetic diseases and predispositions.
In summary, DNA testing commonly involves analyzing blood or cheek swab samples using techniques like RFLP and STR analysis to identify and compare unique genetic markers for various applications.
