SCIN 130 Lab 7: CSI Wildlife, Case 1
CSI Wildlife, Case 1
The scenarios investigated are based on the recently published literature: Wasser, S. K., Brown, L., Mailand, C., Mondol, S., Clark, W., Laurie, C., & Weir, B. S. (2015). Genetic assignment of large seizures of elephant ivory reveals Africa’s major poaching hotspots. Science, 349(6243), 84–87. The underlying data are available on the Dryad Digital Repository: http://dx.doi.org/10.5061/dryad.435p4.
Remember, DNA is made up of nucleotides and an allele is an alternative form of a gene that may be from mutation but is found on the same place in a chromosome in individuals and functions similarly. If you are unfamiliar with these terms, make sure to review them in your book prior to completing the lab.
Specific Lab Instructions
Go to: CSI Wildlife on HHMI Biointeractive
Part 1: The Introduction
- Read the instructions on the home page. Then, watch the opening video from the CSI Wildlife Introduction.
- What is a keystone species?
- Dr. Wasser states that approximately 50,000 African elephants are killed each year. According to the video, it is estimated that there are around 470,000 African elephants. If these numbers are correct, approximately what percentage of African elephants are killed each year? (Show your work.)
- In one or two sentences, summarize Dr. Wasser’s research and how it is being used to conserve elephants.
Part 2: Case One
1. Watch the crime scene video on the first slide of Case One.
2. Explain the goal of the case.
3. Look at the map provided; in what type of location are the majority of African elephants located?
a). Proceed to the How DNA Profiling Works section. What does “STR” stand for and how are they important for identification?
b). Look at the gel on the screen. What do the bands on the agarose gel represent?
c). What is the purpose of the DNA ladder on the agarose gel?
d). DNA profiling is also called DNA fingerprinting. A common misconception about DNA fingerprinting is that the analysis has to do with actual fingerprints. Explain one similarity and one difference between a human being’s pattern of bands on an electrophoresis gel and a human fingerprint.
4. Click on Technique.
a)List three sources to obtain elephant DNA for analysis.
b)Watch the animation on the polymerase chain reaction under Technique. What is the purpose of heating the DNA strand? What is the purpose of cooling the DNA strand?
c)What is the relationship between the size of a DNA fragment and the distance it migrates in the gel?
d)Why does DNA migrate to the positive electrode?
e)Run the gel in the Technique section by pressing the Start button. Which elephant (left or right) has both the largest and smallest fragments? Approximately what size is the largest fragment (bp)? Smallest? .
5. Proceed to the Application section and look at the gel.
For Marker C, are the two elephants in the gel on the left homozygous or heterozygous? How do you know?
6. Read the Review section, and make sure you can answer the questions.
7. Go to Finding a Match
Click on the “+” next to each marker. Compare the bands in the agarose gel from the unidentified elephant and the known elephants. Which elephant (there are two pages of them) matches the unidentified elephant.
8. Watch the video on the “Case Solved” slide.
Name two properties of a good marker and explain why good markers are important.