Gel electrophoresis is a crucial technique used in paternity testing to determine the biological relationship between a child and an alleged father. Here’s how it works:
1. DNA Extraction: DNA is extracted from the cells of the child, the alleged father, and the mother (if available). This DNA contains unique genetic markers that are analyzed during the test.
2. PCR Amplification: Specific regions of the DNA, known as short tandem repeats (STRs), are amplified using a technique called Polymerase Chain Reaction (PCR). These STRs are highly variable among individuals, making them ideal for comparison.
3. Gel Electrophoresis: The amplified DNA fragments are then loaded onto a gel matrix. An electric current is applied, causing the DNA fragments to migrate through the gel. Smaller fragments move faster and travel further than larger ones.
4. Visualization: After electrophoresis, the DNA fragments are stained and visualized under UV light. The pattern of bands on the gel represents the different STRs.
5. Comparison: The STR patterns of the child are compared to those of the alleged father. If the child’s STRs match those of the alleged father at multiple loci, it strongly suggests a biological relationship.
Gel electrophoresis provides a clear and reliable method for comparing genetic markers, making it an essential tool in paternity testing. The results are highly accurate and can conclusively determine paternity in most cases.