Essay Example on DNA: The Unique Identity Code for All Living Organisms

Paper Type:  Essay
Pages:  8
Wordcount:  2029 Words
Date:  2023-01-29


Deoxyribonucleic Acid, abbreviated as DNA, is a group of genetic material contained in the cells of almost all living organisms. The basis of DNA is a sequence of code which is used to develop the proteins in the body which is vital for growth and development of the living organism, and hence the uniqueness of DNA. The aspect of uniqueness then drew researchers to use DNA to establish the identity of the suspect. More than 95% of the DNA is duplicated for all humans; none the less, the small percentage is enough to distinguish between two individuals with some exceptions for twins (Singh, 2016).

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DNA was initially used to prove disputed paternity since the parent's DNA would be similar to the child's. However, in the late 1980s, it was first used in England to solve a case of alleged murder and rape case. Having a unique characteristic makes DNA one of the best ways to prove the existence in the crime scene. It is valuable since each person, with exceptions of twins, has their unique series of the genetic code. It has been proven that DNA samples can remain intact for a very long time, and therefore, reliable in the redemption. DNA is the examination of how the information from a source matches the suspected specimen; hence, occasionally, it is used for solving cases involving the presentation of human materials (Gerlach, 2004).

Like in the previous cases, the first case of the use of DNA in Canada was to solve an example of the alleged rape. The situation in 1989 on the violation of an older woman was convicted based on DNA, the suspect who had earlier claimed innocence was found guilty when the DNA samples from the scene matched his blood. This case marked the beginning of DNA evidence in Canada; after the prosecution, there have been other cases that have marked an important milestone in the use of DNA for evidence purposes. Marc Leduc's situation is such an example; he was found guilty of actively taking part in two murder cases, this was established by the presence of his DNA in both cases (Bonter, De Luca & Guerrini, 2018).

DNA Structure

The DNA molecule is formed by a sequence of nitrogenous bases aligned along with phosphate; the arrangement of these nitrogenous bases determine what type of information will be read out to form proteins. The four nitrogenous bases found in a DNA strand are; thymine (T), guanine (G), adenine (A) and cytosine (C), they are arranged in a double helix manner which allows maximum use of small volumes. The arrangement of this nitrogen bases will determine how the individual's protein will be replicated. At the other side, the phosphate compound form the structural frame for the strand, just below the phosphate are the sequences of the nitrogen bases which alternate according to the pairing with their corresponding nitrogen (Findley, 2001).

At the molecular level space is a rare resource, to cater for the small amount of space while ensuring that all the information is available in the cell, the DNA molecule is divided into smaller sections known as chromosomes. The number of chromosomes varies from species to another; however, with humans, there are twenty-three pairs of chromosomes. These chromosomes are each responsible for the development of various parts of the body, among them are the sex chromosomes which determine the gender of an individual. The presence of a "Y" chromosome will result in the person being male while the absence will lead to one being a female (Huff & Killias, 2010).

Types of DNA

There are various types of DNA which can be characterized by their behavior at different conditions. It was initially believed that the DNA strands only existed in one variation, which is the Right-hand double helix; however, studies have shown that there are other possible forms in which a DNA strand can behave. The B- DNA, which was the original form in which the DNA was thought to take, is the first example. B- DNA is the most stable form of DNA and form the basis for the other derivatives of DNA.

A-DNA and C- DNA

At different humidity, the behavior of DNA strands changes. At 75 % humidity with the presence of sodium, potassium and cesium ions, the tilt of the helix changes to twenty degrees and gains one base pair as from the parent form. Unlike its predecessor, this form is volatile and changes immediately to other types of DNA. On the other hand, C-DNA is formed at 66% humidity with the presence of Lit+ ions. The DNA is at a negative tilt of about negative 7 degrees.


Occasionally the DNA is found in rare situations, D-DNA is one of such types. The number of bases at each turn, unlike other forms, is quite low, it has about eight sets of the nitrogen bases at each corner. The unique style is tilted at a negative sixteen degree; the presence of these forms is minimal and thus is unseen. Among the individual types of the DNA is Z-DNA, it is a reverse of the typical clockwise rotation. It displays a unique anti-clockwise rotation; MIT scientist Rich first discovered this. The Z-DNA has surprisingly been found in many organisms at the lower classes. However, this form is not as different from the original B- DNA as they share some traits. They both exist in a double helix; they both have an antiparallel structure and a three form of a bond, including the G-C relationship (Forr, Schei, Stene, Ormstad & Hagemann, 2018).

Analyzing the DNA

The development of a case will be linked to the availability of evidence that could be presented in a court of law. With DNA Profiling cases, the suspect's information is run against the DNA obtained from the crime scene. The DNA information can be purchased in various ways; for instance, the suspects will be asked to provide a sample that the forensics can run against the example from the scene. DNA can also be obtained from the database, which is kept by the government, as will be discussed below (Lima & Smith 2017).

The testing process begins with the acquisition of a sample from the crime scene; this will be either from blood, skin, hair, or any other body tissue that contains cells with a nucleus. The DNA material is then extracted from the cell nucleus using chemical compounds and heat. The articles are cleaned to ensure that the DNA strands are the only ones available which are then purified to get rid of any form of impurities. The amount of acquired DNA materials is made, and then they are amplified by assigning them color tags, which will help identify the DNA. The profiling is then done by passing the marked DNA under a laser that detects the size and type. These establishments allow the investigators to move to the second face of the investigation.

Typically, the forensics department will use the Short Tandem Repeats for the analysis, also known as STRs. For any individual, there are short sequences such as T-A-G are spread out across the genome. However, these splits are located at specific places and can be counted to ascertain their match. An individual will always have the repeats at a particular spot in the DNA, and hence by matching these repetitions against another DNA one can determine to a high level of accuracy that the suspect was present at the crime scene.

Solving cases in Canada

The arrival of DNA into the scene of forensics has helped exonerate many people who were wrongfully convicted for crimes they never committed. Formerly, hair strand testing was the most widely accepted way of using technology to condemn. This way, however, brought to question when various people were found innocent after the arrival of DNA. The case on a quilt based on scientific evidence has been quite shaky and the jury forced to question its accuracy. DNA's reputation and presumed level of skill has then enabled the method to be acceptable in the field and rarely questionable (McCartney, 2017).

Many individuals have benefited from this kind of evidence, and James Driskell is one of them. He was having been convicted in 1991 for the murder of his friend, Perry Harder who was shot several times in the chest, based on a similarity in the strand of hair found in the car where his friend died. Driskell's case sparked a serious of controversies in the legal field on how far scientific evidence could be accepted. James was later found innocent at the proof of a DNA test that could not place him on the scene.

Likewise, Simon Marshall was cleared of a jail term for sexual offenses in 2003. The man, who was later to e determined as mentally handicapped, confessed to a series of sexual offences that lead to his imprisonment. It was then decided that while his claims would look logical, he was innocent of the crimes convicted. DNA tests proved that the suspect was not the one who took place in the sex claims. He was cleared of all the charges and set free (Martin, 2001).

It is also worth mentioning that during the advent and development of DNA profiling in Canada, the first case was lost due to insufficient proof and availability of doubt. The famous Edmonton case marked the beginning of using DNA fingerprinting in the search for the criminals in Canada. This case did not succeed because though the DNA samples proved the presence of the suspects at the crime scene, the hair and blood samples did not match in all the seven instances. During that time, the knowledge on DNA forensics was still uncommon in the country and hence lack complete certainty by the prosecution (Denov & Campbell, 2005).

Materials for DNA

For the testing of the DNA to be successful, there must be the availability of a material to be tested, and this is achieved through various means as the crime scene is always scattered with evidence. DNA molecules are typically found in any content that contains cells with a nucleus. To run against the evidence, a sample will be obtained from the suspect's blood. The most common types of body materials taken are blood. Testing the blood of a suspect will provide a higher chance of finding cells which have not been exposed to any form of impurities. It is also easy to retrieve from the suspect, and they are more likely to provide the specimen without much hesitation (Rothstein & Talbott, 2006).

However, any other body fluid could be used. The use of semen, for example, from the crime scene, is legible. These tests help proof which the criminal is regardless of the method used. The availability of saliva and cheek swaps also helps the testing of DNA for people who would prefer to do so. It should be noted that any form of body material can be used for the establishment of a DNA result. The evidence will, however, only be legal if the articles are extracted from the suspect by professional personnel in a lab which is recognized by the court.

The DNA Database

The Canadian DNA Database is a collection of DNA information of individuals who have once committed a crime and their DNA taken by the government. This bank of data is used as the primary baseline for running data against another DNA. Entry to this database means that the genetic information will be checked against any new cases suspected to be connected to the criminal or when the researchers do not have any suspect to check on. When data is retrieved from the database, it is legally used to convict an individual regardless of where they are (Hajibabaei, Baird, Fahner, Beiko & Golding, 2016).

On recent years, there have been claims that the government has been using information from companies that are originally meant to help individuals gain access to their relatives. The Golden State Killer who committed several serial cases with a record of about 13 murders and more than fifty rape cases is just an example of this. This felon was later put behind bars many years after their fact was forgotten. A connection was developed through the use of a relativ...

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