Every person is embedded with a genetic blueprint that makes up who they are as a person as they grow older. This is something that all people have and will continue to have until the day they are dead. We, as human beings, need this genetic blueprint as it contains detailed instructions on how our cells should function within our bodies and keep us alive.
This genetic blueprint, otherwise known as the DNA, is crucial for the development of certain characteristics such as hair color, eye color, height, the thickness of hair, and so much more. Those physical traits only comprise around 2% of the total amount of information stored in the DNA. This set of instructions is what is known as coding DNA as they are the sole information that explains the protein exactly how to handle its business. Thus, the reason why we have unique physical appearances.
The remaining 98% of DNA is called the non-coding DNA. The full capabilities of this portion of the DNA are not yet fully known, however, forensic scientists use this to efficiently solve their criminal cases. The science behind the full function of the non-coding DNA may be relatively new, the discovery of short tandem repeats, or STRs for short, is widely used by all forensic scientists today.
Short tandem repeats are important in criminal investigations as they can be replicated and measured to determine the overall DNA profile of a person in question. Almost all types of cells, excluding fully mature red blood cells, contain a set amount of DNA. You can examine almost any bodily fluid such as sweat, saliva, semen, blood, and other DNA sources such as skin cells and fingernails. This abundance of DNA sources can help crime scene investigators solve cases at a much rapid pace as opposed to the more traditional form of investigating.
Although, one thing to note is that most people share the same set of genetic coding in their short tandem repeats as another. Regardless, there are still a select few specific genetic markers that cannot be replicated by any means. Even identical twins would have at least a few different short tandem repeats on their genetic markers to determine which is which.
Every DNA Has a Purpose
You can find traces of DNA in 2 separate places, the inside of the nucleus of a cell or the mitochondria surrounding the nucleus of the cell. The inside portion of the nucleus houses 2 distinct types of DNA: the autosomal chromosome and the sex-defining chromosome.
Let us start with the autosomal chromosome. This type of DNA is the primary aspect that forensic scientists use to determine the subject in question. Except for identical twins, no 2 people should contain the same coding of their autosomal DNA.
The sex-defining chromosomes are much more straightforward in that it indicates whether the subject was either a male or a female. However, there are a few cases in which researching this chromosome could aid in solving a criminal investigation. Oftentimes, this is used to solve the legitimacy of rape cases. The scientists would first research the chromosomes to determine that the victim in question is a female, which contains the X chromosome, and the suspect is male, which should contain the Y chromosome. Y chromosomes are usually subjected through an intense amount of analysis of its STR patterns in the cells to isolate the DNA of the male from the female. That process is known as Y-STR. One thing to note is that the Y chromosome is passed down on the paternal line meaning your brother, father, and all other male children would contain the exact same Y chromosome.
Another type of DNA would be the Mitochondrial DNA, otherwise known as mtDNA. This type of DNA is directly inherited from the mother’s side of the family. Every person that is directly related to the biological mother carries the exact same mtDNA as the rest of your siblings. There is a very rare chance for a slight discrepancy between the offspring’s mtDNA and the mother’s. The mtDNA is commonly used for identifying missing bodies or unidentified remains due to the substance being much more durable and degrades a lot slower than autosomal DNA.
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