Name: Hour: Teacher: ROZEMA Biology Class The Evolution Unit Lessons 7-12 Last Round We Figured Out: How common is Addie s problem? Could it happen to me? Where are bacteria? How do antibiotics work? How do we use them? What happened in our Petri Dishes? How do bacteria grow? This Round We Will Be Working On: How do bacteria get killed? How do antibiotics affect bacteria when put together? How do antibiotics interact with different types of bacteria? How does the environment impact how antibiotics affect bacteria? Why did the antibiotics stop working in Addie? / Why did Addie get so sick? 1 P a g e
What Have We Learned So Far? 2 P a g e
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Lesson 7 Student Activity Sheets: How do bacteria get killed? INVESTIGATION 1: How many doses of an antibiotic would it take to eliminate 1,000,000 bacteria if it was 90% effective? 1. Build a mathematical model to determine how many doses it would take to kill 1,000,000 bacteria if the antibiotic we were using was 90% effective. Use the table to the right to help with this. 5 P a g e
2. Construct a graph of the data in the table you made as a class of # of bacteria vs. # of antibiotic doses. Label your axes, and make sure to choose equal intervals for each axis. 6 P a g e
INVESTIGATION 2: How would both reproduction and repeated doses of antibiotics affect the size of a bacteria population? 3. Let s figure this out by building a new mathematical model to predict what would happen to the population hourly if: we started out with an initial infection of 1,000,000 bacteria; took our first dose of antibiotic immediately (at hour zero); the antibiotic was 99.99% effective; any surviving bacteria continue to double every 20 minutes; and we took another dose every 4 hours for 24 hours. Time (in hrs) # of bacteria alive before dose 0 ----yes ---> 1 no 2 no 3 no 4 ---yes ---> 5 no 6 no 7 no 8 ---yes ---> 9 no 10 no 11 no 12 ---yes ---> 13 no 14 no 15 no 16 ---yes ---> 17 no 18 no 19 no 20 ---yes ---> 21 no 22 no 23 no 24 ---yes ---> Antibiotic dose given? # of bacteria alive after the dose reaches them 4. Was the bacteria population eliminated 24 hours later? 7 P a g e
5. Construct a graph of # Bacteria vs. Time (in hours). Label the axes and the major intervals on both axes. 8 P a g e
MAKING SENSE: 6. Write an explanation that tells how the mathematical model you co-constructed in class helps us understand why it is necessary to take all of the prescribed doses of antibiotics even when we are already feeling better in advance of finishing them. 7. How is what we discovered through this lesson relevant for explaining what might have happened in Addie? 9 P a g e
Lesson 8a Student Activity Sheets: How do antibiotics affect bacteria when they are put together? MAKING PREDICTIONS: 1. A paper disk is soaked in food coloring. This now dyed disk is placed on top of agar in a petri dish. If we check the Petri dish and food coloring in a few minutes, will all of the food coloring remain in the filter paper disk? What do you think will happen? How will we be able to tell? OBSERVATIONS: 2. Answer the following questions about the food coloring demonstration in the box below. Briefly describe the movement of the food coloring once the filter paper disk was placed on the agar. What happened to the strength of the color over the 5 minute period? 10 P a g e
3. You and your small group want to design an investigation that answers: HOW DO ANTIBIOTICS AFFECT BACTERIA WHEN PLACED TOGETHER? Materials you can use: o Petri Dishes with Nutrient Agar o E.Coli Bacteria o Ampicillin Antibiotic o Paper Disks o Masking Tape o Ziploc Bags o Permanent Markers o Rulers What are your ideas for setting up your investigation?? DRAW how you might set up your Petri Dishes below: 11 P a g e
How will your group be able to tell if the antibiotic is killing any bacteria? How would you tell if any of the bacteria are resistant? What type of information does your group plan to collect and find from this investigation? 12 P a g e
MAKING PREDICTIONS: Now that we have designed our experiment, we need to make some predictions about what we think we might see in the Petri dishes when we look at them in a few days. 6. Draw what your experiment looks like as you left it initially in the left box and then what you think you will see in a few days in the box on the right. When drawing your models make sure to consider the differences in antibiotic strength and address the differences you might notice within the different dishes. Make sure you label your drawings and include your reasoning (why do you think you will get these results?) on the lines below. How experimental dishes look at the start: Predict how dishes will look in a few days: Reasoning: 13 P a g e
NEXT STEPS: Think about what we have learned so far about Addie s case and consider the following prompts. Please have these completed and ready to share at the start of next class. 7. Now that we have thought through the setup of an investigation and made some predictions about what we might see, how could the results of this experiment possibly help us in understanding Addie s case? Relate your predictions to Addie s condition. 8. When we make observations in the next lesson, we will be able to collect data that will help us determine what is happening to Addie. However do you think this one data point will be enough to see a pattern in the bacteria growth? Consider possible next steps we might need to take in order to figure out how antibiotic resistance occurs over time. 14 P a g e
Lesson 8b Student Activity Sheets: What is happening with our antibiotic experiments? 1. Sketch the results from your investigation and another group s investigation. My group s investigation results Another group s investigation results 2. Where do you see bacterial growth on the plates? Where are bacteria not growing? 3. What else do you notice looking at the plates? 15 P a g e
SHARING INITIAL IDEAS: 4. What is a specific way that we could test the idea that bacteria close to and farther away from the rings are different from each other? 5. Do you expect any differences between the two plates when we look at them again? How might they turn out differently, if at all? Explain your answer. 16 P a g e
SETTING UP THE INVESTIGATION: Plate your bacteria as much as in 8a, except the bacteria will come from your Petri dishes. Label and prepare two dishes/plates. For the first, collect a sample of E. coli from an area far away from the Zone of Inhibition. Mix this with 50 ml of dechlorinated water to dilute the bacteria. Discard this swab to soak in the 10% bleach solution or place in the Biohazard Bag. Use a new sterile swab to sample the diluted bacteria and streak on the correctly labeled plate (being sure to streak in at least three directions - similar to how you did in investigation 8a). Discard this swab to soak in the 10% bleach solution or place in the Biohazard Bag. For the second dish/plate, follow the steps above, but take a similar amount of bacteria from an area of the plate at the edge of the Zone of Inhibition. Be sure to use new sterile swabs and dechlorinated water. 17 P a g e
MAKING SENSE: Discuss the following with your class. What did we identify as a likely reason for why no bacteria were growing in the Zone of Inhibition? Why did we decide to replate bacteria from the edge of the Zone of Inhibition and also farther away from the Zone? 18 P a g e
Lesson 8c Student Activity Sheets: What is happening with our antibiotic experiments? OBSERVATION: Record what you notice about your experiments in the space below. Include pictures as well as measurements of the zone of inhibition. 1. Sketch your dish, as well as two other groups dishes: Dishes exposed to 5 mg/ 10 ml Ampicillin Dishes exposed to 3 mg/ 10 ml Ampicillin 19 P a g e
Dishes exposed to 1 mg/ 10 ml Ampicillin 2. Record other measurements in the space below or on your data table created in Lesson 8a. ANALYZING AND INTERPRETING DATA: 3. Sharing Initial Ideas: Brainstorm with your small group about why we are seeing these patterns in our data. Jot down some ideas below. 20 P a g e
NEXT STEPS: Answer the following questions in the space below. 4. Why is it important for us to understand what is going on within the different environments of the Petri dish? What is the data telling us? 5. Why is this new evidence important in helping us determine what is going on with Addie s case? 21 P a g e
Lesson 9 Student Activity Sheets: What is happening inside Addie? JIGSAW ACTIVITY: What is your current thinking about why the antibiotics seemed to stop working for Addie? Your group has been assigned one question in the system comparison chart below. Using your Incremental Modeling Tracker as a resource, discuss what you figured out from the different systems and how what you figured out can be used as evidence to help answer the question in your row. Record your thinking in the four blank boxes in the row that corresponds to your assigned question. Be prepared to share what you discuss in your group with the class. For each of the following questions, think about what we have seen/used/learned from our COMPUTER SIMULATION, ADDIE S CASE, and our ECOLI LAB and try and connect it all back to ADDIE to make sense of why the antibiotics stopped working in her: 1. Are there different kinds of bacteria? What s your evidence? 2. Are there different varieties of bacteria within the same kind? What makes a certain variety become a certain variety? What s your evidence? 3. Did the bacteria move into or out of the system? What s your evidence? 22 P a g e
4. Were antibiotics added to the environment? Are the antibiotics and the bacteria interacting? What s your evidence? 5. Were some of the bacteria dying? What s your evidence? 6. How are the bacteria reproducing? What evidence do we have of resources (such as food or space) affecting the reproduction of bacteria? What s your evidence? 23 P a g e
Lesson 10 Student Activity Sheets: How does the antibiotic interact with bacteria in a simulated infection? INVESTIGATION 1: How does the antibiotic interact with the bacteria? MODEL VARIATION: Investigation 1 In this next investigation, you will use a model that has many of the same mechanisms in it that it had before. One change to the simulation is the way that the individual bacteria can vary in the starting population. Bacteria don t just vary based on color; they also vary slightly in the structure of their cell membranes: Notice that each of these four bacteria have a different number of pores (holes) in their cell membranes: The purple one shown on the left has three pores in its cell membrane. The second one is green and it has four pores in its cell membrane. The third one is brown and it has five pores in its cell membrane. The fourth one is red and it has six pores in its cell membrane. PREDICT: Investigation 1 1. If antibiotic particles are released into the simulation, will those particles have the same chance of destroying each of these variations of bacteria when they reach them? Explain. 24 P a g e
PROCEDURE: Investigation 1 In this next investigation, you will start the model with a population of bacteria in the body and administer only one small dose of antibiotic and record your observations. A. Go to http://antibiotics.inquiry-hub.net/ to launch the simulation. B. Set these sliders so that the patient starts with 10 of each individual variation (40 total bacteria): C. Set these sliders so that the patient will get 50 mg of antibiotic with a single dose: D. Turn the REPRODUCE? switch off to prevent bacteria from reproducing: E. Press the SETUP/RESET to initialize the model. F. Then press GO/PAUSE to run the model. G. Press the MANUAL DOSE button. You should see antibiotic molecules at the top of the screen and see them start flowing downward. H. Once all the antibiotic is gone from the environment, pause the model by pressing GO/PAUSE again. I. Record the size of the population at the end of the simulation and the number of each variation in the simulation at this point in the table below. J. Rerun the model a second and third time by repeating the steps above. 25 P a g e
OBSERVATIONS: Investigation 1 Variation At the start of the simulation At the end of the simulation Trial 1 Trial 2 Trial 3 # of pores in the cell membrane Color visualization for this variation # of bacteria the % of the population that is made up of this variation # of bacteria # of bacteria # of bacteria 3 Purple 10 25% 4 Green 10 25% 5 Brown 10 25% 6 Red 10 25% Total bacteria 40 100% DATA ANALYSIS AND RESULTS: Investigation 1 2. Compare your results to your other group members and decide how to best pool all of your trials together to determine any trends in distribution of trait variations in the population at end of one dose of antibiotic. Use the space below for any calculations and use the graph for any data visualization you decide to create. 26 P a g e
3. At the start of this lesson, you predicted whether releasing antibiotic particles into the simulation would result in the same chance of destroying each of these variations of bacteria. What claim can you now make? What evidence do you have for this? How do you make sense of what happened? CONCLUSIONS: Investigation 1 4. In the space below draw a model that helps show why bacteria in this simulation with certain trait variations tend to have a better chance of surviving a single dose of antibiotic compared to other bacteria. Label and annotate your model. 27 P a g e
INVESTIGATION 2: How will the combination of both reproduction and antibiotic application affect the bacteria population? In this investigation, note the following items: Bacteria will reproduce every hour (simulated time). You will start with 40 total bacteria in the infection. In all cases you test, you will add a dose of 150 mg of antibiotics every two hours (simulated time). You will test three different cases of infection. In one case, you will start with an equal number of each variation of bacteria in the population. In the two other cases, you will start with unequal distributions of antibiotics. These three cases are shown in the graphs below: Distribution of trait variations in each infection Initial Infection A Initial Infection B Initial Infection C PREDICT: Investigation 2 5. Do you think it will take the same number of doses of antibiotic to wipe out all the bacteria each time you run the simulation? 28 P a g e
PROCEDURE: Investigation 2 A. Circle the case that you are testing in the table below. Then set these sliders so that the initial population has the corresponding distribution of trait variations in it. Initial Infection A Initial Infection B Initial Infection C B. Set the DOSAGE, AUTO-DOSE?, and DOSE-EVERY values to the ones shown here: C. Set the REPRODUCE-EVERY and REPRODUCE? values to the ones shown here: D. Press the SETUP/RESET to initialize the model. E. Press GO/PAUSE to run the model. F. Let the simulation run for 750 minutes, about six or seven doses of antibiotic. G. One way to speed up the model results is to slide the speed slider to the right. H. If you do that, the graphs and monitors will update very fast, because the computer will skip drawing the image of the bacteria and antibiotics on the screen. To see the image again, return the speed slider back to the middle. I. Press the GO/PAUSE button when there are no bacteria left. Record your observations on the next page. J. Rerun the simulation as many times as your group decided by repeating the previous steps. 29 P a g e
OBSERVATIONS: Investigation 2 Which condition did you start with? (A B C) Trial # Was the infection wiped out? If yes, how many doses did it take? When the simulation stopped, which variation of bacteria was the most numerous? MAKING SENSE: Investigation 2 7. Compare the results among group members: Which condition did you start with? (A B C) Trial # Was the infection wiped out? If yes, how many doses did it take? When the simulation stopped, which variation of bacteria was the most numerous? Which condition did you start with? (A B C) Trial # Was the infection wiped out? If yes, how many doses did it take? When the simulation stopped, which variation of bacteria was the most numerous? 30 P a g e
8. Did it take the same number of antibiotic doses to wipe out all the bacteria each time you ran the simulation? CONCLUSIONS: Investigation 2 9. We discovered that under certain environmental conditions, bacteria with one kind of variation tended to become more common in the population over time. Which kind(s) of bacteria was this? Why did this happen? 10. If a patient was infected by a population made up of 40 of this kind of bacteria, would they be as easy, as hard, or harder to eliminate with antibiotics as a population of the 40 bacteria you started with in Investigation 2, Trial B? Why do you think this? 31 P a g e
11. How is it possible that applying antibiotics can lead to a population of bacteria developing over time that are more resistant to antibiotics than they were initially? 12: Imagine you want to add a single, antibiotic-resistant bacterium to our simulation that was even more resistant to antibiotics than any of the variations that were in the population to start with. Draw a picture of what its cell membrane would look like. Why would this structure give it a competitive advantage for survival over the other variations of bacteria from the simulation? 13: Sketch a graph showing how the introduction of a single bacterium of that type into the environment might affect the proportions of different kinds of bacteria in the population over time: 32 P a g e
Lesson 11 Student Activity Sheets: How does changing the environment that the bacteria are in affect their population? PROCEDURE: A. Go to http://contagion.inquiry-hub.net/ to launch the simulation. B. Start with this population distribution: C. Set the DOSAGE, AUTO-DOSE?, and DOSE-EVERY values to the ones shown here: D. Set the REPRODUCE-EVERY and REPRODUCE? Values to the ones shown here: E. Set the MAX#BACTERIA-TO-TRANSFER to 40: F. Press the SETUP/RESET to initialize the model. G. Press the MANUAL DOSE button once before running the model. H. Press GO/PAUSE to run the model. I. Once the population has grown to over 100 bacteria, press the TRANSFER OUTSIDE >> button. (Make sure that go/pause is still depressed when you do this.) J. Record the distribution of trait variations in the population that are outside the patient. Read these monitors to find those values to record. 33 P a g e
K. Once you record these values, press the << INFECT NEW PATIENT FROM OUTSIDE button. L. Press the MANUAL DOSE button again. M. Repeat the last four steps until you are on the fourth patient. OBSERVATIONS: Variation Bacteria in the infection Patient 1 Patient 2 Patient 3 Patient 4 # of pores in the cell membrane Color visualization for this variation # of bacteria % population made up of this variation # of bacteria % population made up of this variation # of bacteria % population made up of this variation # of bacteria % population made up of this variation 3 purple 4 10% 4 green 8 20% 5 brown 12 30% 6 red 16 40% Total bacteria 40 100% 40 100% 40 100% 40 100% 34 P a g e
MAKING SENSE: Sketch graphs of your results. Distribution of trait variations in each infection Patient 1 Patient 2 Patient 3 Patient 4 1. Compare the graphs among other students. What do you notice happening to the distribution of traits in this population over time? CONCLUSIONS: 2. How do the results of the simulations in Lessons 10 and 11 help you explain how it is possible that applying antibiotics can lead to a population that becomes more resistant to antibiotics than they were initially, even when individual bacterium traits are not changing and the trait variations that an offspring inherits are identical to those of its parent? 35 P a g e
Putting It All Together Now you are to take EVERYTHING we have learned, and put it together to create a FINAL, ACCURATE model to represent WHY ANTIOBITICS STOPPED WORKING IN ADDIE. Things to remember: Label everything. Add captions for explanation and context. Be specific and detailed. Your model should VISUALLY explain what happened. Focus only on events that directly impacted the bacteria in Addie. Focus on the bacterial populations in Addie and the antibiotics given. 36 P a g e
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