DNA Evidence Evaluation

Lab 14 – Who Ate the Cheese?

Objectives: In this simulation you will examine crime scene evidence to determine who is responsible for eating the Queen's special imported Limburger Cheese (yes, the stinky cheese). You will model the process of electrophoresis and DNA fingerprinting.

To begin, please read the Royal Guard Incident Report on page 2, then return to this page and begin the DNA Evidence Evaluation.

DNA Evidence Evaluation

  1. Look at your DNA sequences sheet with the molecular bases. The restriction enzyme cuts at every point it finds C C G G, always cutting between the C and the G. Use a pencil to simulate the cutting of the DNA sequence by putting a line between the C C and G G points and its base pair below it.

Example:

CTACCGGAT

GATGGCCTA

  1. Count the number of base pairs in each of the DNA sequences you cut. Record the base pair number below the DNA fragment.

Example:

CTACCGGAT

GATGGCCTA

5 4

  1. Shade your DNA fragments (sequences) in the Electrophoresis Data Chart, page 3, using the base pair numbers as a guideline for fragment placement.
  1. Compare the crime scene DNA to the suspects and indicate on your chart, which suspect is guilty of eating the cheese.

Analysis

  1. On your chart, circle the suspect's DNA who matches the DNA at the crime scene and write the name of the suspect. Support your answer. __
  1. Identify the procedure used to obtain these results._______________
  2. Which chemicals are used to cut DNA into fragments for this gel electrophoresis procedure?

ROYAL GUARD INCIDENT REPORT

Incident Data

Incident Type:

Theft

Complaint Status:

Pending DNA results

Processed by:

Chief Wiggam

Other Officers:

Officer Li Gase

Property

Property Code:

Rare cheese

Owner's Name:

Queen Elizabeth

Name:

Limburger

Value:

$12,000

Burglary Data

Method of Entry: Unknown, no evidence of force on doors or windows.

Narrative: The cheese was allegedly stolen from the Queen's sitting room the night before the grande ball. The cheese was listed as a gift from the Manchurian diplomat. Officer Li Gase dusted for fingerprints and found none on the table or doors, the maid claimed that they had been wiped clean earlier. The wheel of cheese was on a platform in the sitting room, and half of it had been eaten. We took pictures of the half eaten cheese and sent it to the lab for further tests. Edna N. Zime, the lab technician said that saliva samples could be taken from the teeth imprints of the cheese that was left behind.

Suspect Data

Suspect Number 1
Name: Princess Dubbah Elix
Description of Suspicion: The princess was seen entering the sitting room earlier in the evening. She is well known for her love of cheese.

Suspect Number 2
Name: Electra Foresis
Description of Suspicion: Electra was recently involved in a relationship with the Manchurian diplomat that sources say ended badly. Her motive may have been to sabotage the diplomat's gift to the Queen.

Suspect Number 3
Name: Ada Nine
Description of Suspicion: Ada was the maid in charge of cleaning the sitting room. She had access to the cheese.

Suspect Number 4
Name: Gene Tics
Description of Suspicion: Gene is the leader of the local Cheese-Makers Guild, he may not have wished for Queen Elizabeth to have cheese from anywhere but his own guild.

Crime Lab Data

Crime Lab Investigator:

R. Renee

Lab Technician:

Edna N. Zime

List of Evidence Received:

Plastic bag with cheese crumbs

List of Procedures Used:

DNA extraction
Polymerase Chain Reaction
DNA restriction Analysis

Narrative: After receiving the package with the plastic bag marked Crime Scene, the DNA was extracted. Because the sample was so small, the DNA was amplified using the polymerase chain reaction. We isolated the DNA from the four suspects and compared them to the crime scene DNA using DNA restriction analysis.

Results: See attached DNA Results

Who Ate the Cheese? Electrophoresis Data Chart

Crime

DNA

Suspect

1

Suspect

2

Suspect

3

Suspect

4

# of

Base Pairs

         

31

         

30

         

29

         

28

         

27

         

26

         

25

         

24

         

23

         

22

         

21

         

20

         

19

         

18

         

17

         

16

         

15

         

14

         

13

         

12

         

11

         

10

         

9

         

7

         

6

         

5

         

4

DNA Sequences

DNA Sequences Image 1

DNA Sequences

DNA Sequences Image 2
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