DNA Profiling Reaveals Unique Patterns
Definition
DNA profiling
DNA profiling is a technique used to identify individuals based on unique patterns in their DNA.
- DNA profiling is a cornerstone of forensic science, used to match DNA from crime scenes to suspects.
- Even a tiny sample, like a drop of blood or a strand of hair, can be amplified and analyzed to identify a suspect or exonerate the innocent.
- This is done by relying on regions called short tandem repeats (STRs) short sequences of DNA that repeat multiple times.
- The number of repeats varies greatly between individuals, making STRs ideal for distinguishing one person from another.
How DNA Profiling Works
- Sample Collection: DNA is obtained from sources like blood, saliva, or hair.
- Amplification with PCR: Specific STR regions are amplified using PCR, producing enough DNA for analysis.
- Separation by Gel Electrophoresis: The amplified DNA fragments are separated based on size, creating a pattern of bands unique to the individual.
- The reliability of DNA profiling increases with the number of STR markers analyzed.
- Using more markers reduces the probability of a false match, enhancing the accuracy of the results.
- In a paternity test, the child’s DNA profile is compared to that of the mother and the potential father.
- If the child has bands not present in either the mother or the alleged father, another person must be the biological parent.
In forensic investigations, analyzing 13 or more STR markers is standard practice, making it extremely unlikely for two unrelated individuals to have identical profiles.
Other Applications
1. Disease Diagnosis
- PCR is used to detect genetic mutations linked to diseases like cystic fibrosis or sickle cell anemia.
- It can also identify pathogens in infectious diseases, such as detecting viral RNA in COVID-19 testing.
In COVID-19 testing, PCR amplifies viral RNA (converted to DNA) to detect the presence of the virus, even in very small quantities.
2. Evolutionary Biology
- Gel electrophoresis helps compare DNA from different species to study evolutionary relationships.
- By analyzing similarities and differences in DNA fragments, scientists can construct phylogenetic trees.
3. Environmental Monitoring
- PCR and gel electrophoresis are used to detect DNA from endangered species in environmental samples, aiding conservation efforts.
- These techniques can also identify microbial communities in soil or water, helping monitor ecosystem health.
Remember that PCR amplifies specific DNA sequences, while gel electrophoresis separates them by size. These complementary techniques are the backbone of many modern biological applications.
Self reviewCan you explain how PCR and gel electrophoresis work together in DNA profiling? What are some other applications of these techniques?
