How Can We Use Forensic Science To Solve A Murder?
The Mission
On February 8, 2018, Carleton Comet was murdered outside of San Marin High School while he was at a picnic. Our job was to use multiple methods of forensics analysis to establish the murderer and their motive.
We had some background information on the set of suspects that were present at the picnic. Combined with the forensic evidence found at the crime scene, we had all the data that we needed. |
Genetics
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Heredity
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Methods
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Genetics
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Genetic Engineering
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Dominance
Offspring produced through sexual reproduction receive two sets of alleles; one from the mother, and one from the father. The expression of these alleles in relationship to each other represents the dominance of the alleles. There are several types of dominance. Typically, with 2 alleles, there would be one dominant allele and one recessive allele. This means that the expression of the dominant allele would completely mask the effects of the other, or recessive, allele. If a flower had a red and white allele, and red was dominant, the flower would be red.
Incomplete Dominance
Incomplete dominance is another form of dominance in alleles. This type of dominance means that both alleles are expressed, with neither allele being dominant over the other. Using the example of red and white alleles in a flower, under incomplete dominance, the flower would be pink.
Co-dominance
Co-Dominance is a third type of hereditary dominance. Under this scenario, both alleles would be expressed in tandem. This would mean that under a white and red allele scenario, the flower could either be red with white spots or white with red spots.
Pedigree Chart
These charts show the pedigree, or family history of an individual or group of people. In our investigation, we used the individual stories of the suspects to patch together a network of relationships between them, and also any hereditary diseases that may have affected them.
Ink Chromatography
In order to find out who was the owner of the pen that was used to write the death threat, we used ink chromatography analysis. Strips of paper with samples of ink were put into alcohol, which drew out the colors that made up the ink. Then, the different pens could be compared in order to have a definitive answer.
Karyotypes
Karyotypes, or visual representations of an organism's chromosomes, were used to provide some insight on the state of health of some of the suspects. Besides showing sex, the karyotypes were able to show if there were any chromosomal diseases that could have an impact on the mental health of the suspects.
Mutation: The altering of the genomic structure. There are several types of mutations.
Point mutations change a small set of base pairs through substitution, also called misense if referring to a single base pair. Nonsense occurs when there is an early stop codon.
Frameshift mutations alter DNA through an insertion or deletion of a base pair, therefore affecting all codons downstream of the mutation.
Point mutations change a small set of base pairs through substitution, also called misense if referring to a single base pair. Nonsense occurs when there is an early stop codon.
Frameshift mutations alter DNA through an insertion or deletion of a base pair, therefore affecting all codons downstream of the mutation.
For a lab during this unit, we did simple genetic engineering by transforming a pGLO plasmid into bacteria. Our results are below.
Reflection
This project was one that our class was looking forward to for most of the year. The project was intended to be one that was mostly student analyzed, with the teacher only setting us up with the necessary knowledge. In that regard, we believe that it worked. However, as a group, we had our own set of strengths and weaknesses. One of the latter was attendance. Out of a smaller group of three, it was more common to only have two people in class on any given day. This was due to a plethora of reasons, from sickness to extracurriculars. Despite that, one of our strengths was communication. We were able to communicate what was to get done each day in order to meet our deadlines. This was achieved not only by word of mouth, but also by working on the project outside of school.
This project was somewhat unique for me. The group that I started with was not the one that I ended up presenting with. This was mostly due to the fact that my first set of peers was exceptionally dysfunctional . My inability to work with them would be a personal weakness. After trying to get my group in a generally straight course for some weeks, the only other option was to join a group that had lost a member and therefore was a group of two. My ability to transfer what little had been achieved in my previous group into the new group, and synthesize the new information presented would be a personal success that I would be proud of.
This project was somewhat unique for me. The group that I started with was not the one that I ended up presenting with. This was mostly due to the fact that my first set of peers was exceptionally dysfunctional . My inability to work with them would be a personal weakness. After trying to get my group in a generally straight course for some weeks, the only other option was to join a group that had lost a member and therefore was a group of two. My ability to transfer what little had been achieved in my previous group into the new group, and synthesize the new information presented would be a personal success that I would be proud of.