In numerous movies and dramas, you have watched the police arrest criminals with various methods. Specifically, “Money Heist”, one of the most famous crime thriller dramas on Netflix, shows several intriguing mechanisms to identify who the heists are. In some specific scenes, police obtain information on the past residence where the criminals have stayed and find some evidence which they had used, like spoons, chopsticks, and cigarette butts. Then, a few hours after they investigate those findings, police can detect who the robbers are. It sounds interesting, but what does it make that possible? Does it work in reality?
What is DNA profiling?
One method enables those astonishing scenes in the drama in reality too. A key method is called DNA profiling (DNA fingerprinting). To begin with, DNA is a molecule in our cells that contain our hereditary information, so everyone has a distinct structure with different genetic information. DNA profiling is a process of investigating each individual’s genetic information by obtaining a sample of DNA from organisms that researchers would like to examine.
How does it work?
To investigate one person’s DNA, researchers should extract specific samples of DNA from targets. The samples are formed with certain structures, called Short Tandem Repeats (STR). STR are alleles that repeatedly appear between two and seven in tandem at certain loci in DNA sequences. They can be found in various evidence, like saliva, blood, or skin cells. After obtaining suitable samples, investigators can amplify DNA sequences from STR by PCR test. PCR test is one of the methods to generate numerous copies of DNA efficiently.
After amplification of DNA patterns, researchers can cut DNA up to different sizes by enzymes called restriction endonuclease. This type of enzyme is a protein that can cleave DNA at certain parts, known as recognition sequences. These pieces of genetic materials are put into Agarose to progress Gel Electrophoresis. It is a method to separate DNA fragments by their sizes, and some particular patterns with several lines appear. These patterns are moved onto the specific plate, the Nylon sheet. Finally, Investigator can compare this sample to others’ information.
Applications of DNA profiling
1. Identification of criminals
When one crime occurs, numerous ideas regarding criminals are not known. However, if there are some pieces of evidence biologically concerning criminals like hair, saliva, or fur, police can extract them from the crime scenes. Then, police select some suspects and obtain biological evidence from them. Then, investigators use DNA profiling with the extracted samples. After making results, researchers compare those DNA extracts with one in the crime scenes. If there is a person who has the most similar DNA patterns with the criminal’s samples, police can judge who is an actual criminal.
2. Paternal Test
If someone is curious about whether his offspring is a true person descended from him or not, many people usually experience this test. This is similar to the previous application. First, testers should obtain DNA from the mother and father. After that, they need to extract from the offspring. Next, DNA fingerprinting will detect the patterns of people: mother, father, and son/daughter. If they are in a biological family, these patterns of offspring appear similar to the parents. However, if they are not real parents, the pattern looks different.
Prospects of DNA profiling
After DNA profiling is invented, numerous mysterious events especially in the field of archaeology, criminology, and biology are solved, so this method has enormous impacts on the entire society around the world. Therefore, the more developed our biotechnology is, the more efficient and creative pathways regarding the identification of DNA will be improved. For example, in the movie 'GATTACA’, one person is investigated within 10 seconds after his blood was extracted. This situation currently looks impossible due to the limitations of our technology, but it is very possible in the foreseeable future. Additionally, this method can be involved in the utilization of artificial intelligence (AI), so the rapid development of AI will significantly affect some ways in regard to DNA profiling. As a result, the outcomes from DNA profiling will be stronger and identified faster.
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