DNA Lab Report: How DNA is Used to Identify a Crime Suspect?

Introduction

Before the 1950s it was not yet known that molecules of living organisms were used to store information, and pass traits that it holds on to offspring. However, in 1953 Rosalind Franklin, James Watson, and Francis Crick were able to determine the structure of DNA’s double helix design. DNA consists of two strands that are twisted around one another and these polymers are held together by hydrogen bonds formed between the base pair of nucleotides (McDonald & Lehman, 2012). Now, much more is known about DNA how it works, and how it is structured.

Deoxyribonucleic acid (DNA) is present in every single living cell, and thus it contains the genetic material that acts as a blueprint for protein synthesis by living cells. Within DNA there are areas that vary among different individuals. These areas of DNA are called ‘genetic polymorphisms.’ Upon examination of these areas of the DNA cells, a person can determine another’s ‘DNA fingerprint.’ DNA polymorphisms are used now for the determination of paternity and maternity, identification of human remains, the genetic basis of inherited conditions, and kinship (California State, n.d.). A concept called DNA fingerprinting, also known as DNA typing or DNA profiling, was first used in the United Kingdom by a geneticist called Dr. Alex Jeffreys in 1984 (California State, n.d.).

Additionally, the first conviction, with the aid of DNA testing fingerprinting, occurred in November of 1987 in Orlando, Florida. Since then, it has aided in tens of thousands of criminal investigations. Over 100 convicted prison inmates have seen their charges dropped and erased because of new DNA evidence in their case. Some of these cases were on Death Row (California State, n.d.). DNA identification is now a very important element of criminal investigations around the world and has allowed for a more concrete justice system.

To remove the DNA from cells, they need to first be broken open. Detergents, the solutions, are used to break these cells open by breaking down the cell membrane and other membranes, and this includes the nuclear membrane of the cell. These detergents interact with the phospholipids in said membranes, and it disrupts the interactions that hold the cells together. Thus, they are broken down. DNA is held together with proteins, so this helps to expose the sensitive information of the DNA; the information that is needed to determine connections (California State University, n.d.). This experiment will break down the cells, expose the DNA, and allow for the exposure of the DNA so it can be compared to others in a criminal investigation.

Objectives

The objectives of this lab report are to prove how DNA is used to identify crime suspects. More specifically, it is being used to ‘solve’ the crime of the murder of Hank Schrader, an Assistant Special Agent with the Drug Enforcement Agency in Albuquerque, New Mexico. The question is in regards to which person could have killed him, and the suspects are Heisenberg (Walter White), Gustavo Fring, or Jesse Pinkman. An important objective was that Hank was killed in the desert far outside of the city, $80 million in evidence had been stolen, and Jesse Pinkman is an eyewitness to the crime.

Hypothesis

It is believed that Gustavo Fring shot Hank in the desert in order to steal the whole amount of $80 million. If the suspect Gustavo Fring killed Hank, then the DNA from the crime scene will then match Fring’s DNA.

Methods and Materials

Experiment 1:

Supplies:

DNA from the three suspects: Fring, White, and Pinkman

Solution A - detergent and sodium chloride

Solution B - ethanol

Glass beakers

Glass stir rods

Cheesecloth

Plastic jars with lids

Procedure:

1. Obtain all three pieces of DNA. Follow this procedure with each set of DNA for each suspect.

2. Place the tissue in the plastic jar, and add the detergent-NaCl solution (also called solution A in the supply list). Add enough so it is equal to the amount of DNA.

3. Put on the lid and shake vigorously until mixed well.

4. Obtain a section of cheesecloth that is large enough to cover the opening of the glass beaker. Use only two layers of cheesecloth! This will act as a filter for your DNA material.

5. Place the mixture in the cheesecloth and allow filtering through the cheesecloth into the beaker. A clear liquid should be present.

6. To that clear liquid, slowly add along the side enough of the ethanol solution (also called solution B in the supply list) that it is equal in volume to the amount of the filtered banana/detergent/salt mixture.

7. This DNA will be compared to the DNA results of Walter White, Jesse Pinkman, and Gustavo Fring.

Experiment 2:

Supplies:

DNA samples

MW standard sample

Electrophoresis Buffer

0.8 % Agarose Solution

Ethidium Bromide

Safety Gloves

Procedure:

Prepare agarose gel in the casting tray;

Remove and blocks, comb and submerge gel under buffer in electrophoresis chamber (DNA samples);

Attach safety cover, connect leads to the power source and conduct electrophoresis;

After electrophoresis, transfer the gel for staining.

For 100 series: Use InstaStain Methylene Blue; analyze on white light source after destaining.

For 100 Q series: InstaStain Ethidium Bromide; analyze on a UV transilluminator (no destaining).

View the DNA staining and photograph; compare DNA samples.

Results

The results of the experiment are that the DNA extraction was a success; the DNA from Walter White, Gustavo Fring, and Jesse Pinkman. From the results, through both experiments, the investigation was able to conclude that Gustavo Fring murdered Hank Schrader, in the New Mexico desert, in order to steal the evidence that Hank had earlier taken in his investigation. The hypothesis was supported by what was found during the experimentation.

The theory based on the separation of DNA was proven in the experiments. In the first experiment, the cells were broken and, because of this, the important information was exposed and this was recorded in order to be compared in the criminal investigation.

Experiment: DNA Extraction. The second experiment was not completed; no images were available.

Discussion

The final step in the experimentation process is a simple process in lining up the sample profiles next to one another, and comparing the sample from the crime scene to the three samples from the suspects. “The more segments the two samples have in common, the more likely it is that the samples came from the same person” (Nova, 2012). The hypothesis was supported by the information found at the time of DNA extraction during the experiment. There were two very important elements of this experiment: the concept of extracting DNA being one of them and the crime being solved.

Conclusion

The expectations regarding the experiment were met, and my hypothesis was proven through the DNA analysis. The experiment itself may be improved by improving the complexity of the method. However, this method worked for the case this time and it was able to solve the case about who killed Hank Schrader. The procedures and experiments can be related to life outside of the course because it is a good lesson in academics and in other areas of life. To take the time to carefully extract DNA, two different ways takes a lot of determination and concentration, and focus.

References

California State Polytechnic University. (N.d.). Writing a Formal Lab Report. In BIO 115 Laboratory – Basic Biology, pp. 43-46. Print.

California State Polytechnic University. (N.d.). How is DNA used to identify a Crime Suspect? In BIO 115 Laboratory – Basic Biology, pp. 73-80. Print.

McDonald, J., & Lehman, D. C. (2012). Forensic DNA analysis. Clinical Laboratory Science, 25(2), 109-13. Retrieved from http://search.proquest.com/docview/1115028324?accountid=458.

Nova. (2012). Create a DNA Fingerprint. Public Broadcasting Station. Retrieved from http://www.pbs.org/wgbh/nova/education/body/create-dna-fingerprint.html.