Analyzing Genetic Evidence

Analyzing Genetic Evidence Click & Learn Student Worksheet INTRODUCTION This worksheet walks through Case One and Case Two of the CSI Wildlife Click & Learn, except for the Frequency Primer section at the end of Case One. A separate document, entitled “Frequency Primer,” may be used for that section. In this Click & Learn, you will analyze genetic evidence to solve two cases of elephant poaching based on real events. PROCEDURE As you go through the Click & Learn, follow the instructions below and answer the questions in the space provided. CSI Wildlife Introduction Read the introduction and watch the opening video. 1. What is a keystone species? A keystone species is a species which if removed would cause the decline of an ecosystem. 2. 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. 50,000/470,000 would mean 10.6% of African elephants are killed each year. 3. In one or two sentences, summarize Dr. Wasser’s research and how it is being used to conserve elephants. Dr. Wasser's research is being used to deduce the areas where elephant ivory comes from using DNA testing and then having law enforcement focus on those areas. Case One Watch the video and read the introduction on the first slide (“The Crime Scene”). 4. Explain the goal of the case. The goal is to identify the origin of the ivory to better protect against poachers. 5. Look at the map on the screen. List the region or countries the majority of African elephants inhabit. African elephants primarily inhabit the DR of the Congo and close surrounding areas. Page 1 of 4 :A An nalyz lyzin in ingg G Geenetic Evid videence Clic Clickk & Le Learn arn Stu Studen den dentt Work orksh sh sheet eet 1 Go to the next slide (“How DNA Profiling Works”) and read through the Background section. 6. Look at the gel on the screen. What do the bands on the gel represent? The bands on the gel represent the DNA profile. 7. 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. A humans DNA fingerprinting and actual fingerprint are both unique to a single individual however findgerprints are very visible trait whereas DNA fingerprinting requires special equipment to see. Read through the Technique section. 8. A scientist makes primers specific to a particular STR fragment. These primers are then used to amplify the STR fragment from 10 different elephants. Would you expect the fragments to be the same size in all the elephants? Explain your answer. Due to 10 different elephants having unique DNA to each individual elephant the fragments would not be the same. 9. What is the relationship between the size of a DNA fragment and the distance it migrates in the gel? THe longer fragments travel shorter distances makeing the relationship between size and distance inverse. Run the gel on the screen by pressing the Start button. 10. Which elephant (left or right) has both the largest and smallest fragments? Right 11. Approximately what sizes (in bp) are the largest and smallest fragments? 190bp largest, 63 bp smallest Read through the Application section. 12. Look at the gel on the screen. For Marker C, are the two elephants shown homozygous or heterozygous? How do you know? Heterozygous because 2 different bands appear on the gel. 13. Why do you think scientists use multiple markers to identify individual elephants? using more markers means less chance of similarites. Page 2 of 4 Analyz lyzin in ingg G Geenetic Evid videence Clic Clickk & Le Learn arn Stu Studen den dentt Work orksh sh sheet eet 1 Answer the questions in the Review section. 14. Show how you calculated the number of base pairs in the 10-repeat unit. 10*4=40+9=49bp Go to the next slide (“Finding a Match”) and answer the question, then watch the video on the “Case Solved” slide. 15. Name two properties of a good marker and explain why good markers are important. High variabiklity and ability to amplify Case Two Watch the video and read the introduction on the first slide (“The Crime Scene”). 16. In Case One, you were looking for a match with an individual elephant. How does Case Two differ from Case One? looking for a region with multiple types of elephants the tusk came from. Go to the next slide (“Building a Reference Map”). Read through the Background, Technique, and Applications sections. 17. For the gel in the Applications section, why does the lane for the ivory sample contain only two bands while the other lanes (A and B) have multiple bands? ivory sample is of individual elephant where as lane A and B is the composition of all alelles. 18. If an ivory sample has two alleles that are also found in a population sample, does that tell you with certainty that the ivory sample came from that population? Explain your answer. No, narrows down which population with ivory would be near. Answer the questions in the Review section. 19. If the scientist had collected 20 dung samples, would you expect more bands, fewer bands, or the same number of bands on the gel? Explain your answer. Page 3 of 4 Analyz lyzin in ingg G Geenetic Evid videence Clic Clickk & Le Learn arn Stu Studen den dentt Work orksh sh sheet eet 1 Go to the next slide (“Finding a Location”). Answer the questions until you reach the Eliminating North, East, or South section. 20. The three populations that were chosen for further analysis are geographically distant from one another. Why does this approach make more sense than choosing three populations that are geographically close to one another? allows for a larger area to be studied and eliminates larger areas when studying DNA 21. In the “Eliminating North, East, or South” section, which population did you eliminate, and which marker(s) helped you make this choice? 22. In the next section, which population did you eliminate, and which marker(s) helped you make this choice? North population becuase it did not have some of the alelles present. Read through the last slide of Case Two (“Case Solved”). 23. By analyzing many more markers and all the populations, Dr. Wasser linked these seized ivory tusks to which country? East africa Ivory Trade Watch the video and read through the final slide (“Stopping Illegal Poaching”). 24. Name two reasons elephant populations are threatened. Habitat destruction and ivory poaching 25. The introduction to the Click & Learn mentioned that elephants are a keystone species. Based on your knowledge of this term, explain in your own words why it is important to the ecosystems of Africa to save the elephant populations. Without them being around th dig waterholes and trappling dense areas, many other species could not survive the habitat in Africa. Page 4 of 4