Why Is Probability Important in DNA Fingerprinting?
For DNA profiling, why is the probability so significant? Because every event has a posterior probability. When the posterior probability is high (a high possibility that the sample will match), then we can say that an individual is unique from others in the population. When it is low (a low possibility that the sample will match), we can conclude that an individual is not unique. Probability is what makes our work more accessible; it is a powerful tool for statistics and measurements.
Why is probability significant in DNA fingerprinting? Probability, in DNA profiling, can be described as a statistical concept that involves an immense range of measurement and analysis tools. Like any other sciences or application, it too has its limits. As stated earlier, we cannot test for every possible DNA sample with the same statistical power. Hence, we have to make do with probability estimates, which are highly dependent on how we want to use the data.
Like frequencies, there are also threshold values in DNA fingerprinting, which refers to the maximum percentage of matches we expect from a DNA sample. The threshold value is usually set at 50%. The use of these thresholds is to maximize the efficiency of the whole process and prevent false results.
Three standard testing methods are applied in DNA profiling: Polymerase chain reaction (PCR), shotgunning, and hybridization. Each one has its shortcomings that should be weighed against its strengths when deciding on which testing method to use in a particular case. Here is a summary of each testing methodology.
Polymerase Chain Reaction (PCR): This is the most commonly used DNA testing technique. To perform, DNA samples are broken up using guanidine hydrochloride and then analyzed using restriction enzymes. After the completion of this complicated procedure, several bands are formed. These bands are further broken by washing with buffer solution and finally processed for appearance and purity. The overall analysis of the sample yields a profile that is relative to the individual DNA template contained in the model.
Shotgunning: Another frequently applied DNA testing methodology uses a shotgun format. The DNA samples are broken up using restriction enzymes and then subjected to multiple sessions of amplification and screening. In the first session, the target sequence of the DNA template is read using PCR amplifiers. After this, several frequency bins containing repetitive DNA fragments are randomly chosen. Then the sample is processed using specific primer and fluorescent probes to identify the fragment’s location and identity.
Hybridization: Also known as Polycomb DNA Polymerization, this technique involves repeated restriction enzymes on the sample. The restriction enzymes are designed to specifically attack the sequence of DNA that is complementary to the target sequence. For instance, if the target sequence is a human gene called Humanucleoside, restriction enzymes can hybridize this gene with a primer that only affects DNA identical to Humanucleoside. After hybridization, the test can be performed.
Summary: The three primary DNA testing methodologies discussed above can be very useful in determining the DNA sample source. However, one question that often comes up is why probability is essential in DNA fingerprinting? It is critical in assessing the quality of the DNA samples and the genotype of individuals. Using susceptible DNA testing methods and applying mutagenic and annealing temperature cycles on the samples, it is possible to determine the model’s source accurately. This is why it is essential always to follow the manual procedures of handling the selection and collecting the DNA samples correctly.