Write and defend a claim about DNA

DNA’s role in forensic science I the most accurate and reliable type of evidence there is. Compared to fingerprinting or eyewitness testimony, Which both have inherent flaws and inaccuracies. DNA evidence is a highly effective way to match a suspect to biological samples collected during a criminal investigation.

The chemical structure of DNA is a molecule that consists of two long polynucleotide subunits. Each of these chains is known as a DNA strand. Nucleotides are compared of a five-carbon sugar to which are attached one or more phosphate groups and  nitrogen base. In case of the nucleotides in DNA, the sugar is deoxyribose attached to a single phosphate group. The base may be either Adenine (A), Cytosine (C), Guanine (G), and Thymine (T). These four types of subunits are strung together to create the backbone. With the four types of subunits are cut this is A restriction enzyme is a protein that recognizes a specific, short nucleotide sequence and cuts the DNA only at that specific site, which is known as restriction site or target sequencestandard-dna-backbone

Gel Electrophoresis is the process of separating biomolecules of different sizes by running them through a sievelike matrix using electricity. The larger molecules move more slowly while the smaller molecules slip through the matrix and more faster and farther, thus separating the different fragments based on size.


The claim that I have about DNA is that, DNA’s role in forensic science is the most accurate and reliable type of evidence. The support I have for that statement is in paragraph of the article “The Exonerated 37”. In the article it says “37 men spent years, and in some cases decades.” These men and many more who were not mentioned in this article were all innocent and were convicted of a crime they did not commit.  Also in the article when these men were on trial and at times their testimony was backed up by a rudimentary serology which is very odd to me because in a serology test that looks for antibodies in your blood. This kind of test is only to see what viruses and bacteria you carry in your body. Also a type of serology test is the testing of the blood, which will test the blood found at the crime scene. The only problem with this would be you would only receive blood type and nothing else. Gathering people with the same blood type of that, that was tested. Then hopefully you pick the right person standing on the line in front of you. That makes for more error.

One possible argument that could go against my claim would be that DNA is not the most reliable type of evidence out there. No laboratory test is 100% accurate, but DNA tests are pretty close. The reason someone will argue about DNA not being reliable is that innocent people are going to prison because the DNA sample matches that of someone else. With testing DNA to someone else there is a 1 in 200 chance that a given individual will test as  a positive match with the DNA of someone else.

Fingerprints, palm prints and sole prints have been used as identification tools by law enforcement. Collectively known as “Friction ridge analysis,” This forensic method involves examiners comparing the details of an unknown print with a set or a database of known prints. With this there is so much room for error because in the fingerprint database if there is a match anywhere then the suspect would be convicted guilty.

The purpose of the claim is that, is DNA the most accurate source of evidence out there? Defending my claim with facts and evidence from Socratic seminar articles to prove that DNA is the most reliable source of evidence until proved wrong by another source or technology.



DNA fingerprinting 

Late night at the park someone was raped. At the scene was finger prints on a weapon which was a knife. DNA finger prints were taken and now they have two suspects, which one was the one who did the raping.  

 As you can see in the picture that suspect 1 and the sperm DNA match up. They have to be in the same sequence, that is how you can find out who did the crime.  DNA is first cut with restriction enzyme. Once the DNA has been cut, the fragments must be separated according to size using Gel Electrophoresis. DNA is from the gel is then transferred to a nylon filter, which makes the DNA single stranded pieces of DNA stranded. After the DNA is single stranded, the radioactive probes are applied.