1. DNA Collection:
- A small sample of cells is collected from an individual, usually from the inside of the cheek, blood, or other body fluids.
- The sample is then sent to a laboratory for DNA extraction.
2. DNA Extraction:
- The cell sample goes through a DNA extraction process to isolate and purify the DNA.
- This process involves breaking open the cell membranes and removing proteins and other cellular material.
- The end result is a concentrated sample of DNA.
3. DNA Amplification:
- The extracted DNA sample is too small for direct analysis, so it needs to be amplified to create millions of copies of specific DNA regions.
- This is done using a technique called polymerase chain reaction (PCR).
- PCR uses specialized enzymes and temperature cycles to make multiple copies of the DNA regions of interest.
4. Gel Electrophoresis:
- The amplified DNA fragments are separated according to their size using a technique called gel electrophoresis.
- DNA fragments are placed in a gel made of agarose and an electric current is passed through it.
- Smaller DNA fragments move faster through the gel, while larger fragments move slower.
5. Visualization and Analysis:
- After electrophoresis, the gel is stained with a special dye that binds to DNA.
- The DNA fragments are then visualized under a UV light, creating visible bands on the gel.
- The pattern of bands is unique for each individual and is referred to as a DNA profile.
6. Comparison:
- The DNA profile of the unknown sample is compared to a known reference sample, such as a sample from a crime scene or a DNA database.
- If the band patterns match, it suggests that the DNA samples belong to the same individual.
- If there are differences in the band patterns, it indicates that the DNA samples are from different individuals.
7. Statistical Analysis:
- In forensic cases, statistical analysis is performed to determine the probability that two DNA profiles match by chance.
- This involves calculating the frequency of the specific DNA variations (alleles) in the population.
- A high match probability provides strong evidence that the DNA samples belong to the same individual.
DNA profiling is a powerful technique widely used in various fields, including forensic science, paternity testing, medical diagnosis, and genetic research. It provides accurate and reliable identification and analysis of DNA samples, making it an essential tool in both scientific and legal contexts.
