Name Module 2 Activity Help Solve Who Attacked Ma

Name Module 2 Activity Help Solve Who Attacked Ma

Name Module 2 Activity Help Solve Who Attacked Ma

Name____________________ Module #2 Activity: Help solve who attacked Margie Hightower! DNA samples were collected from the victim, suspects, and from the evidence at the crime scene. Many copies of each DNA sample were made using PCR. But, in order to figure out who attacked Ms. Hightower, you will need to first create a DNA fingerprint for each sample, and then evaluate the differences.

Below are sections of the DNA samples from each. Step 1. Restriction Enzymes. We will examine differences in to short tandem repeat (STR) sites in the DNA samples. Site #1 has the repeat CCACGT , and site #2 has the repeat CGC . Cut the DNA with the appropriate restriction enzyme, EcoRI. An example of how EcoRI cuts DNA is seen at the right. The first DNA sample (victim) is cut for you. Determine the DNA footprint of sites 1 and 2 for the other collected samples. (a) Victim: CCGAGAGAATTCCCACGTCCACGTGAATTCCGCCGCCGCCGCCGCCGCCGCGAATTCTA GGCTCTCTTAAGGGTGCAGGTGCACTTAAGGCGGCGGCGGCGGCGGCGGCGCTTAAGAT Answer: Site 1 : (14bp long) Site 2 : (23bp long) AATTCCCACGTCCACGTG AATTCCGCCGCCGCCGCCGCCGCCGCG GGGTGCAGGTGCACTTAA GGCGGCGGCGGCGGCGGCGGCGCTTAA (b) Suspect #1: CCAGAATTCCCACGTCCACGTGAATTCCGCCGCCGCCGCCGCCGCCGCCGCGAATTCTA GGTCTTAAGGGTGCAGGTGCACTTAAGGCGGCGGCGGCGGCGGCGGCGGCGCTTAAGAT Answer: Site 1_______ Site #2________ c) Suspect #2 AGAATTCCCACGTCCACGTCCACGTCCACGTGAATTCCGCCGCCGCCGCGAATTCTACTA TCTTAAGGGTGCAGGTGCAGGTGCAGGTGCACTTAAGGCGGCGGCGGCGCTTAAGATGAT Answer: Site 1_______ Site #2________ d) Evidence (hair sample) CGAGAGAATTCCCACGTCCACGTGAATTCCGCCGCCGCCGCCGCCGCCGCGAATTCTAT GCTCTCTTAAGGGTGCAGGTGCACTTAAGGCGGCGGCGGCGGCGGCGGCGCTTAAGATA Answer: Site 1_______ Site #2________ e) Evidence (blood sample) CAGAATTCCCACGTCCACGTCCACGTCCACGTGAATTCCGCCGCCGCCGCGAATTCTAT GTCTTAAGGGTGCAGGTGCAGGTGCAGGTGCACTTAAGGCGGCGGCGGCGCTTAAGATA Answer: Site 1_______ Site #2________ Step 2. Gel Electrophoresis. In order to visualize the difference in STRs between the DNA samples, scientists must run the DNA out on an agarose gel, which separates the DNA pieces from one sample based on size. You will run out all your samples on the gel below. *Make sure to draw the DNA bands in the appropriate gel (look at which DNA probe is being used) ( Victim ) ( Blood ) ( Hair ) ( S #2 ) ( S #1 ) ( Blood ) ( Hair ) ( S #1 ) ( S #2 ) ( Victim ) Gel #1 (DNA probe: CCACGT ) Gel #2 (DNA probe: CGC) ( 50 bp ) ( 20 bp ) ( 30 bp ) ( 15 bp ) ( 10 bp ) ( 40 bp ) ( 5 bp ) Step 3. Analysis. Based on the DNA evidence above, answer the following questions. a) What conclusions can you make about the DNA collected from the hair sample left at the scene of the crime? How do you know? b) What conclusions can you make about the DNA collected from the blood sample left at the scene of the crime? How do you know? c) Which suspect should the police arrest for this crime? Explain.

Paper For Above instruction

The investigation into the attack on Margie Hightower involves a detailed DNA analysis to identify the perpetrator. The process begins with digestion of DNA samples using restriction enzymes, specifically EcoRI, which cuts DNA at specific sequences. This step allows for the creation of DNA fingerprints based on different fragment lengths resulting from the restriction enzyme digestion. By analyzing the fragment sizes at STR sites, we can compare the victim’s DNA to suspect and evidence samples to find matches.

In the provided data, the victim's DNA is already cut, revealing two distinct fragment sizes at the STR sites: 14 base pairs (bp) at site 1 (with the repeat CCACGT) and 23 bp at site 2 (with the repeat CGC). These serve as reference points for comparing other samples. The suspect DNA samples undergo similar digestion, producing unique fragment sizes at each site. Suspect #1’s DNA shows a fragment length of 14 bp at site 1 and 23 bp at site 2, which matches the victim’s profile perfectly, suggesting a potential match. Suspect #2’s DNA, however, exhibits different fragment sizes, indicating differences at the STR sites, and thus, likely not the attacker.

The evidence samples, one hair and one blood, also contain DNA fragments that can be analyzed. The hair sample shows fragment sizes consistent with suspect #1 for both sites—14 bp and 23 bp respectively—indicating that the DNA from the hair at the scene matches Suspect #1’s DNA profile. The blood sample's fragment sizes do not match Suspect #1, further indicating that the attacker’s DNA is unlikely from Suspect #1. Conversely, the hair evidence correlates with Suspect #1’s DNA, and the blood evidence does not, reinforcing that Suspect #1 is the most probable attacker based on the DNA evidence.

Following gel electrophoresis, DNA fragments are separated by size, with smaller fragments traveling faster and farther on the gel. The bands observed in the gel are compared against a DNA size marker (50 bp, 40 bp, etc.) to determine the sizes of the fragments for each sample. For the victim and evidence samples, the appearance of bands at positions corresponding to 14 bp and 23 bp confirms the previous restriction enzyme analysis. The banding pattern for Suspect #1 aligns with the victim’s, indicating they share the same STR profile at these sites. The suspect #2’s bands differ, ruling them out as the attacker.

Therefore, integrating the restriction digestion data with gel electrophoresis results, the evidence strongly suggests that Suspect #1 is the perpetrator. The match of DNA profiles at the critical STR sites provides compelling biochemical evidence linking Suspect #1 to the crime scene and supporting their arrest.

References

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