Biology Commonwealth of Virginia
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Sample assessmentHave students draw a diagram of nucleotide mutations similar to the diagrams of gene mutations in the Content/Teacher Notes above. Use A-T, G-C to indicate nucleotides. Have students create a list of genetic variations and mutations that could be beneficial and a list of variations and mutations that could be harmful. Have students create a list of common diseases, and hold a class discussion on whether or not those diseases have a genetic component. Follow-up/extensionHave students research malaria and sickle cell anemia, explaining why the sickling of the cells was beneficial to those who lived in malaria-prone countries. Challenge students to research antibiotics and use the growth curve created in the activity to explain why it makes sense to take the entire dosage of a prescribed antibiotic. Resources“Astrobiology Evolution.” http://www.science.gmu.edu/~hgeller/astrobiology/AbEvolvlect.doc. Provides features of a sample phylogenetic tree. Bren, Linda. Battle of the Bugs: Fighting Antibiotic Resistance. http://www.fda.gov/fdac/features/2002/402_bugs.html. Genetic Algorithms in Plain English. http://www.ai-junkie.com/ga/intro/gat1.html. “How big a problem?” Microbes: What doesn’t kill them makes them stronger. University of Wisconsin. http://whyfiles.org/038badbugs/scope.html. Contains information on antibiotic-resistant microbes. How do mutations and chromosome abnormalities cause human disease? http://w3.dwm.ks.edu.tw/bio/activelearner/15/ch15intro.html. Contains a simple mutation assessment. “It’s all in the Teamwork.” Microbes: What doesn’t kill them makes them stronger. University of Wisconsin. http://whyfiles.org/038badbugs/mechanism.html. Contains information on antibiotic-resistant microbes. Mathematical Biology. http://www.bath.ac.uk/math-sci/research/math-biology.html. Department of Mathematical Science, University of Bath, UK. Mixing the Gene Pool. http://www.stanford.edu/group/Urchin/whysex.htm. This simulation is designed to demonstrate that sexual reproduction mixes the gene pool and why this is an advantage. Mutations and Antibiotic Resistance in Staphylococcus Bacteria Student Activity Sheet Name: Date:IntroductionEver since antibiotics became widely available about 50 years ago, they have been hailed as miracle drugs — magic bullets that are able to destroy disease-causing bacteria. However, with each passing decade, bacteria that resist not only single, but multiple antibiotics have become increasingly widespread, making some diseases particularly hard to control. In fact, according to the Centers for Disease Control and Prevention (CDC), virtually all significant bacterial infections in the world are becoming resistant to the antibiotic treatment of choice. For some of us, bacterial resistance could mean more visits to the doctor, a lengthier illness, and possibly drugs that are more toxic. For others, it could mean death. The CDC estimates that each year, nearly 2 million people in the United States acquire an infection while in a hospital, resulting in 90,000 deaths. More than 70 percent of the bacteria that cause these infections are resistant to at least one of the antibiotics commonly used to treat them. Antibiotic resistance, also known as antimicrobial resistance, is not a new phenomenon. Just a few years after the first antibiotic, penicillin, became widely used in the late 1940s, penicillin-resistant infections emerged that were caused by the bacterium Staphylococcus aureus (S. aureus). These "staph" infections range from urinary tract infections to bacterial pneumonia. Methicillin, one of the strongest drugs in the arsenal used to treat staph infections, is no longer effective against some strains of S. aureus. Vancomycin, which is the most lethal drug against these resistant pathogens, may be in danger of losing its effectiveness; recently, some strains of S. aureus that are resistant to vancomycin have been reported. If they are not naturally resistant, bacteria can become resistant to drugs in a number of ways. They may develop resistance to certain drugs spontaneously through mutation. Mutations are changes that occur in the genetic material, or DNA, of the bacteria. These changes allow the bacteria to fight or inactivate the antibiotic. Bacteria also can acquire resistant genes through exchanging genes with other bacteria. The bacteria reproduce rapidly, allowing resistant traits to quickly spread to future generations of bacteria. This means that resistance can spread from one species of bacteria to other species, enabling them to develop multiple resistances to different classes of antibiotics. (See: http://www.fda.gov/fdac/features/2002/402_bugs.html)
1. Fill in Table 1 on the next page to determine the exponential growth of one Staph aureus cell. Assume that all the requisite conditions are optimum for the cell to grow and divide. Also assume that toxic byproducts of respiration are flushed from the environment. If the Staph aureus generation time is 20 minutes (m), determine how many cells will be present after 4 hours (h) and 20 minutes (m) has passed. Table 1
2. In the graph below, label the y-axis as numbers of Staph aureus cells with intervals of 100. (Each square represents 100 more individual cells.) Label the x-axis as time in 20-minute intervals. 3. Using a black pencil or pen, plot the table above as number/time of bacteria on the graph. (Generations 1–11). Graph 1. Staph aureus growth
4. Suppose at 3h40m, the cells are competing for dwindling food and nutrients, exponential growth stops, and the number of bacteria stabilizes. Follow the next generation’s numbers in Table 2. Plot the numbers of Staph aureus colonies on the graph. Table 2
5. Toxic waste products build up, food is depleted, and the Staph aureus cells begin to die, as shown in Table 3. Table 3
6. Label the growth curve in the correct places with the following labels: Lag Phase: Generations 0–6 Log Phase: Generations 7–12 Stationary Phase: Generations 13–22 Death Phase: Generations 23–31 Antibiotic Resistance. Suppose this host body has Staph aureus food poisoning. Given enough time (black growth curve), toxic waste products could build up, or the host body’s immune system could kill the Staph aureus cells, and the food intoxication would be over. If the host were given antibiotics at generation 17, the death of the Staph aureus may be more immediate and the host body would feel better rapidly. However, some of the Staph aureus cells may mutate and thus be able to resist the effect of the antibiotic. 7. Plot the following colony counts for each scenario. With a blue pencil or pen, start at Generation 17 for No AR. (No AR = No Antibiotic Resistance) With a red pencil or pen, start at Generation 17 for AR. (AR = Antibiotic Resistance) Table 4
Directory: testing -> sol -> scope sequence scope sequence -> History and Social Science Standards of Learning Enhanced Scope and Sequence sol -> Strand Earth Patterns, Cycles, and Change Topic Investigating fossils in sedimentary rock Primary sol testing -> Prairie State Achievement Exam testing -> Testing and Assessment updated Tentative schedules testing -> Local unit tests Located at module-name sol -> P. O. Box 2120 Richmond, Virginia 23218-2120 sol -> Strand Interrelationships in Earth/Space Systems Topic Investigating ocean currents Primary sol sol -> History and Social Science Standards of Learning for Virginia Public Schools Wo Board of Education Commonwealth of Virginia March 2015 History and Social Science Standards of Learning for Virginia Public Schools Adopted in March 2015 by the Board of Download 3.95 Mb. Share with your friends:
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