Lab Instructions_ Cell Biology Act I Mission Memo (Spring A 2024 Onward)

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Lab Instructions: Cell Biology Act I Mission Memo Greetings Fellow Explorer: The spotted gliders in the Allurian Forest need your help! Many gliders have succumbed to a mysterious illness. Thanks to your careful analysis, we now have a probable diagnosis: cancer. Still, cancer doesn't usually affect a large fraction of a population. Therefore, we must learn what caused this widespread disease and decide how to treat it. Use the following questions to guide your work: ● Are elevated concentrations of carcinogens in water, air, or soil to blame for the widespread cases of cancer in spotted gliders? (Appendices 1 and 2) ● How could a malfunction in cellular communication have caused the cancer in spotted gliders? (Appendix 3) Universally in your debt, The AI

Note: You will be using the program Microsoft Excel for this assignment. We have provided links to Excel tutorials and transcripts where applicable, to help you answer the questions. Appendix 1 Could the widespread cases of cancer in spotted gliders be explained by elevated levels of carcinogens in the water? Cancer results from mutations in genes that cause cells to reproduce uncontrollably. Often, these mutations occur when certain chemicals from the environment—called carcinogens —interact with the genetic material in cells. At low concentrations, carcinogens present a low risk of cancer. However, an artificial environment such as the Intergalactic Wildlife Sanctuary could contain elevated levels of carcinogens. Some known carcinogens are found in the structural framework of the sanctuary. Therefore, the carcinogens could have accumulated in the water, air, or soil of the Allurian Forest. The Intergalactic Wildlife Federation (IWF) follows the health and safety recommendations of the Galactic Environmental Treaty, which limits the concentrations of potentially harmful chemicals. This treaty specifies that drinking water should contain less than 10 micrograms of a given carcinogen per liter (< 10 µg/L). Any concentration greater than this limit could increase the risk of cancer. Your water samples from the Allurian Forest are critical for determining whether a carcinogen could have caused the tumors in spotted gliders. Why? Since we don’t have data on the concentration of carcinogens in the tissues of sick and healthy spotted gliders, knowing the concentration of carcinogens in the water where the sick spotted gliders were found is the next best set of information to help us determine if elevated concentrations of carcinogens could be to blame for the widespread cases of cancer in spotted gliders. We will follow three steps to answer the question “Could the widespread cases of cancer in spotted gliders be explained by elevated levels of carcinogens in the water?” Step 1: Anticipate your analysis : Determine what you should observe if the concentration of carcinogen in water exceeds the recommended limits. This step will help us identify the evidence needed to build an argument in Step 3.

Step 2: Calculate the probability that the concentration of carcinogen in water exceeds the recommended limit of 10 µg/L: Determine whether the concentration of carcinogen in water likely exceeds the recommended limits. This step gives us the evidence needed to build an argument in Step 3, when we will conclude if an elevated concentration of carcinogens in the water could explain the widespread cases of cancer in spotted gliders. Step 3: Weigh the evidence and conclude if an elevated concentration of carcinogens in the water could explain the widespread cases of cancer in spotted gliders: Construct an argument to answer the question “Could the widespread cases of cancer in spotted gliders be explained by elevated levels of carcinogens in the water?” Your argument should draw on your calculations in Steps 1 and 2.

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Step 1: Anticipate your analysis. To construct a sound argument, one must anticipate the evidence needed to support a claim. In this assignment, you can choose between two claims: ● Potential Claim 1: Yes, the widespread cases of cancer in spotted gliders could be explained by elevated levels of carcinogens in the water. ● Potential Claim 2: No, the widespread cases of cancer in spotted gliders could not be explained by elevated levels of carcinogens in the water. The figure below shows the mean concentration of carcinogen in the water at three different locations. In the figure, the y-axis represents the mean concentration of carcinogen, with higher values indicating more carcinogen. The x-axis represents the different locations where the water was tested for the carcinogen. The dashed line indicates the recommended limit of carcinogens, 10 µg/L (µ is the Greek letter “mu” and µg is the abbreviation for micrograms per liter [L] of water; µg/L). Finally, the solid circles represent the mean concentration of carcinogen in the water at each location. Figure 1.0. 1. Select the location that best illustrates what one should expect to observe if the concentration of carcinogen in water exceeds the recommended limit of 10 µg/L. a. Location A b. Location B c. Location C Highe r numb er Mean concentration of carcinogen ( µ g/L) Lowe r numb er Location Location A Location B Location C Recommende d limit for health of 10 µg/L

Step 2: Calculate the probability that the concentration of carcinogen in water exceeds the recommended limit of 10 µg/L . Excel tutorials: ● #6 Functions: Describing Data ; #6 Functions: Describing Data transcript ● #7 Functions: The Count Family and Absolute Cell References ; #7 Functions: The Count Family and Absolute Cell References transcript ● #8 Calculating Frequencies ; #8 Calculating Frequencies transcript ● #10 Estimating Parameters of a Normal Probability Distribution ; #10 Estimating Parameters of a Normal Probability Distribution transcript ● #11 Calculating a Probability from a Normal Probability Distribution ; #11 Calculating a Probability from a Normal Probability Distribution transcript To determine if the widespread cases of cancer in spotted gliders could be explained by elevated levels of carcinogens in the water, we will need to determine whether the concentration of carcinogen in water exceeds the recommended limit. To do this, we must estimate the probability that the water contains a concentration of carcinogens greater than 10 µg/L. Before we can estimate that probability, we must determine whether a normal probability distribution reasonably describes the frequency distribution of carcinogen concentrations. If not, we should use the data to calculate the probability instead of using a normal probability distribution. Download the Excel file titled “Act I: A Mysterious Disease Workbook,” containing the concentrations of carcinogen in 20 water samples collected from the Allurian Forest. Then, decide whether the data can be modeled with a normal probability distribution. We need to be sure the data meet the assumptions of this model before using it to draw conclusions. Directions : For questions 2-4, download the “Act I: A Mysterious Disease Workbook” from your Canvas assignment and refer to the sheet titled “Question 2,” containing the concentrations of carcinogen in water samples from the Allurian Forest (sample size = 20 water samples). Use Excel for calculations, modeling, and graphing. Round all calculated values to the nearest tenth of a decimal place. For example, if you calculate the value as 3.8218, round to 3.8. 2. Use the sheet (tab) labeled “Question 2” to create a plot of a frequency distribution (also known as a histogram) of the concentration of carcinogen in water (sample size = 20 water samples). Your plot should follow the formatting guidelines listed below. Hint: If you are having trouble with the cell formatting when entering the bin ranges in your spreadsheet, format only the bin range cells as “Text.” Excel tutorials:

● #8 Calculating Frequencies ; #8 Calculating Frequencies transcript ● #9 Saving Plots as Images ; #9 Saving Plots as Images transcript Formatting Instructions ● Chart type: 2D Bar Chart ● Chart title: “Frequency of Carcinogens in Water” ● Y-axis title: “Frequency”; Font size = 18 ● Y-axis numbers: Font size = 14 ● X-axis title: “Concentration of Carcinogen (µg/L)”; Font size = 18 ● X-axis numbers: Font size = 14 ● Bins = Use the following 6 bins: 0-1, 1-2, 2-3, 3-4, 4-5, 5-6 3. Based on the frequency distribution, does a normal probability distribution reasonably model the concentration of carcinogen in water? ● No, a normal distribution does not reasonably model the concentration of carcinogen in water. 4. Explain your answer to the previous question. Be sure to discuss the assumptions of a normal probability distribution and why, based on the frequency distribution, these assumptions seem appropriate (or not) for modeling the concentration of carcinogen in water. ● It’s assumed that a normal distribution has a shape of a bell curve, with a mean,median and mode that are all equal. As we see in this graph the normal probability distribution doesn’t reflect any that I mentioned . The histogram that I created does not resemble a bell curve and doesn't have

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an equal mode, mean or median. Therefore, it doesn’t resemble a normal probability distribution. It shows more of a skewed distribution, to the left of the graph. Now that we have determined whether the data can be reasonably modeled by a normal probability distribution, we can estimate the probability of observing a certain concentration of carcinogen in the water of the Allurian Forest. Your approach to estimating this probability should depend on whether the data can be reasonably modeled by a normal probability distribution. Let's compare two approaches, one that uses a normal probability distribution and one that uses only the data. Note: You will answer both approaches (questions 5 and 6), regardless of your answers to questions 3 and 4. Approach 1: Use the normal probability distribution to estimate the probability Let’s assume that a normal probability distribution reasonably describes the data. In this case, you should use the following approach to estimate the probability that the concentration of carcinogen in water exceeds the recommended limit of 10 µg/L: (1) Estimate the mean and standard deviation of the concentration of carcinogen. (Excel tutorial #10 Estimating Parameters of a Normal Probability Distribution ; #10 Estimating Parameters of a Normal Probability Distribution transcript ) (2) Use the normdist function of Excel to calculate the probability that a water sample has a carcinogen concentration greater than 10 µg/L, given the mean and standard deviation. (Excel tutorial #11 Calculating a Probability from a Normal Probability Distribution ; #11 Calculating a Probability from a Normal Probability Distribution transcript ) Directions : For question 5, use the Act I: A Mysterious Disease Workbook and refer to the sheet titled “Q5-6 Water Concentration Prob,” containing the concentrations of carcinogen in water samples from the Allurian Forest (sample size = 20 water samples). Use Excel for calculations, modeling, and graphing. 5. Assuming the data are reasonably modeled by a normal probability distribution, calculate the probability that water from Alluria contains more than 10 µg of carcinogen per liter (> 10 µg/L). Express your answer as a percentage (%). Round all calculated values to the nearest tenth of a decimal place. For example, if you calculate the value as 3.8215%, round to 3.8%. Hint: Format only the cell with your completed function as “Number.” Excel tutorial:

● #11 Calculating a Probability from a Normal Probability Distribution ; #11 Calculating a Probability from a Normal Probability Distribution transcript ) Probability that the concentration of carcinogen in water exceeds the recommended limit of 10 µg/L = 0 % using = 1-norm.distribution Approach 2: Use the data to estimate the probability Excel tutorials: ● #6 Functions: Describing Data ; #6 Functions: Describing Data transcript ● #7 Functions: The Count Family and Abs Cell References ; #7 Functions: Describing Data transcript ● #8 Calculating Frequencies ; #8 Calculating Frequencies transcript Now, let's assume that a normal probability distribution fails to reasonably describe the data. In this case, you should use the following approach to estimate the probability that the concentration of carcinogen in water exceeds the recommended limit of 10 µg/L: 1. Count the number of water samples with more than 10 µg/L. 2. Divide the number of water samples with more than 10 µg/L by the total number of water samples (20). Convert this value to a percentage by multiplying by 100. Directions : For question 6, use the Act I: A Mysterious Disease Workbook and refer to the sheet titled “Q5-6 Water Concentration Prob,” containing the concentrations of carcinogen in water samples from the Allurian Forest (sample size = 20 water samples). Use Excel for calculations, modeling, and graphing. 6. Assuming the data are not reasonably modeled by a normal probability distribution, calculate the probability that water from Alluria contains more than 10 ug of carcinogen per liter (> 10 µg/L). Express your answer as a percentage (%). Round all calculated values to the nearest tenth of a decimal place. For example, if you calculate the value as 3.8218%, round to 3.8%. Excel tutorials: ● #6 Functions: Describing Data ; #6 Functions: Describing Data transcript ● #7 Functions: The Count Family and Absolute Cell References ; #7 Functions: The Count Family and Absolute Cell References transcript ● #8 Calculating Frequencies ; #8 Calculating Frequencies transcript Probability that the concentration of carcinogen in water exceeds the recommended limit of 10 µg/L = 0 = Count H20 Prob by using the Countif function

Step 3: Weigh the evidence and conclude if an elevated concentration of carcinogens in the water could explain the widespread cases of cancer in spotted gliders. Because of your careful planning in Step 1 and your quantitative analyses in Step 2, you can now conclude if an elevated level of carcinogens in the water could explain the widespread cases of cancer in spotted gliders. Be sure to provide your reasoning, highlighting the relevant evidence supporting your claim. Note: Use the following criteria to determine whether the concentration of carcinogen exceeds the recommended limit: the probability of observing a concentration of carcinogen in water that exceeds 10 µg/L must be greater than 5%. 7. Select the claim that is better supported by the evidence. a. Yes, the widespread cases of cancer in spotted gliders could be explained by elevated levels of carcinogens in the water. b. No, the widespread cases of cancer in spotted gliders could not be explained by elevated levels of carcinogens in the water. 8. Summarize the evidence that supports your claim, including how you determined whether the concentration of carcinogen in water exceeds the recommended limit (or not), based on probability. Use quantitative evidence when possible. ● According to my findings, the spread of cancer in the spotted gliders can not be determined by the elevated levels of carcinogens in the water. There are 0 water samples with more than 10 µg/L. The concentration of carcinogens in the water exceeds the recommended limit of 10 µg/L is 0 %. Appendix 2 Could the widespread cases of cancer in spotted gliders be explained by elevated levels of carcinogens in the air or soil? Through your hard work, we now have a much better sense of whether the widespread cases of cancer in spotted gliders could be explained by elevated concentrations of carcinogens in the water in Alluria.

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However, carcinogens can enter an organism through air and soil, in addition to water. Fortunately, GUS recorded the concentrations of carcinogen in samples of air and soil around Alluria. We need to analyze the concentrations of carcinogen in these samples as we did for the water samples to determine if the widespread cases of cancer in spotted gliders could be explained by elevated concentrations of carcinogens in the air or soil of Alluria. Part 1 - Concentration of carcinogen in the air The concentration of carcinogen in air is measured in units of micrograms of carcinogen per cubic meter of air (µg/m 3 ). The Galactic Environmental Treaty recommends that air contains a concentration of a given carcinogen that is less than 10 µg/m 3 . Figure 1.1. The frequency distribution of the concentration of carcinogen in air samples collected in the Allurian Forest. The red line shows the normal probability distribution that best describes the data. Excel tutorials: ● #10 Estimating Parameters of a Normal Probability Distribution ; #10 Estimating Parameters of a Normal Probability Distribution transcript ● #11 Calculating a Probability from a Normal Probability Distribution ; #11 Calculating a Probability from a Normal Probability Distribution transcript I have concluded that a normal probability distribution reasonably models the concentration of carcinogen in air. The mean concentration equals 0.97 µg/m 3 and the standard deviation equals 0.20 µg/m 3 . Given this information, you can calculate the probability that the concentration of carcinogen in air samples exceeds the

recommended limit of 10 µg/m 3 . Directions: For questions 9-11, use the Act I: A Mysterious Disease Workbook and refer to the sheet titled “Q9-11 Air Concentration Prob,” containing the concentrations of carcinogen in air samples from the Allurian Forest (sample size = 20 air samples). Use Excel for calculations, modeling, and graphing. 9. Calculate the probability that air from Alluria contains more than 10 µg of carcinogen per cubic meter (> 10 µg/m 3 ). Express your answer as a percentage (%). Round your answer to the nearest tenth of a decimal place. For example, if you calculate the value as 3.8218%, round to 3.8%. Hint: Format only the cell with your completed function as “Number.” Excel tutorial: ● #11 Calculating a Probability from a Normal Probability Distribution ; #11 Calculating a Probability from a Normal Probability Distribution transcript Probability that air contains more than 10 µg/m 3 of carcinogen = ● by using the =1-norm.distribution function the probability is 0% You can now conclude whether the concentration of carcinogen in air exceeds the recommended limit. Be sure to provide your reasoning, highlighting the relevant evidence supporting your claim. Note: Use the following criteria to determine whether the concentration of carcinogen in the air exceeds the recommended limit: the probability of observing a concentration of carcinogen in air that exceeds 10 ug/m 3 must be greater than 5%. 10. Select the claim that is better supported by the evidence. a. Yes, the widespread cases of cancer in spotted gliders could be explained by elevated levels of carcinogens in the air. b. No, the widespread cases of cancer in spotted gliders could not be explained by elevated levels of carcinogens in the air. 11. Summarize the evidence that supports your claim, including how you determined whether the concentration of carcinogen in air exceeds the recommended limit (or not), based on probability. Use quantitative evidence when possible. ● In my findings,I determined that the concentration of carcinogens in the air does not exceed the recommended limit. I calculated the probability and found it to be 0%.

Part 2 - Concentration of carcinogen in soil The concentration of carcinogen in soil is measured in units of micrograms of carcinogen per kilogram of soil (µg/kg). The Galactic Environmental Treaty recommends that soil contains a concentration of a given carcinogen that is less than 10 µg/kg. Figure 1.2. The frequency distribution of the concentration of carcinogen in soil samples collected in the Allurian Forest. The red line shows the normal probability distribution that best describes the data. Excel tutorials: ● #10 Estimating Parameters of a Normal Probability Distribution ; #10 Estimating Parameters of a Normal Probability Distribution transcript ● #11 Calculating a Probability from a Normal Probability Distribution ; #11 Calculating a Probability from a Normal Probability Distribution transcript I have concluded that a normal probability distribution reasonably models the concentration of carcinogen in soil. The mean concentration equals 290.16 µg/kg and the standard deviation equals 28.85 µg/kg. Given this information, you can calculate the

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probability that the concentration of carcinogen in the soil exceeds the recommended limit of 400 µg/kg. Directions: For questions 12-14, use the Act I: A Mysterious Disease Workbook and refer to the sheet titled “Q12-14 Soil Concentration Prob,” containing the concentrations of carcinogen in soil samples from the Allurian Forest (sample size = 20 soil samples). Use Excel for calculations, modeling, and graphing. 12. Calculate the probability that soil from Alluria contains more than 400 µg of carcinogen per kilogram (> 400 µg/kg). Express your answer as a percentage (%). Round your answer to the nearest tenth of a decimal place. For example, if you calculate the value as 3.8218%, round to 3.8%. Hint: Format only the cell with your completed function as “Number.” Excel tutorial: ● #11 Calculating a Probability from a Normal Probability Distribution ; #11 Calculating a Probability from a Normal Probability Distribution transcript Probability that soil contains more carcinogens than 400 µg/kg = 0% using =norm.distribution You can now conclude whether the concentration of carcinogen in soil exceeds the recommended limit. Be sure to provide your reasoning, highlighting the relevant evidence supporting your claim. Note: Use the following criteria to determine whether the concentration of carcinogen exceeds the recommended limit: the probability of observing a concentration of carcinogen in soil that exceeds 400 µg/kg must be greater than 5%. 13. Select the claim that is better supported by the evidence. a. Yes, the widespread cases of cancer in spotted gliders could be explained by elevated levels of carcinogens in the soil. b. No, the widespread cases of cancer in spotted gliders could not be explained by elevated levels of carcinogens in the soil. 14. Summarize the evidence that supports your claim, including how you determined whether the concentration of carcinogen in soil exceeds the recommended limit (or not), based on probability. Use quantitative evidence when possible. ● The spread of Cancer in spotted gliders can not be determined by the

elevated levels of carcinogens in the soil. Based on my findings of there being 0% probability regarding the concentration of carcinogens in the soil that exceeds 400 µg/kg. The probability is below 5% which indicates that it is unlikely that the soil is causing the spread of cancer among the gliders.

Appendix 3 How could a malfunction in cellular communication have caused the cancer in spotted gliders? Cancerous cells reproduce uncontrollably. Normally, cells receive signals from their environment that communicate whether to reproduce - we call this cell division . However, a malfunction in the proteins of a signaling pathway can cause a cell to reproduce without the appropriate signals (or to ignore signals to stop reproducing). Thus, cancer results from a breakdown in communication among cells. To investigate the malfunction that caused the tumors of spotted gliders, we must identify proteins that are critical for regulating cell division. Figure 1.3 shows the signaling pathway in spotted gliders in which cell division occurs rapidly in the presence of a signaling molecule. By contrast, cell division in spotted gliders occurs slowly in the absence of the same signaling molecule. Figure 1.3. The signaling pathway that regulates cell division in spotted gliders. Upper left: The signaling molecule (SR1) binds to the receptor (R1). Center: When no signaling molecule is bound to the receptor, most proteins in the signaling pathway are inactive, but a protein that represses cell division (CDI2) is active. Right: When a signaling molecule is bound to the receptor, most proteins in the signaling pathway

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become active. The first three proteins in the pathway (KR1-KR3) are activated by phosphorylation. The protein KR3 inactivates CDI2, which prevents CDI2 from inhibiting cell division. KR3 also activates CDP1, which directly promotes cell division. We will follow two steps to answer the question “How could a malfunction in cellular communication have caused cancer in spotted gliders?” Step 1: Analyze the signaling pathway to determine the consequence of a malfunction in the receptor : Predict what you would observe if the receptor remains active, even in the absence of a signal. This step will enable us to determine whether a malfunction in the receptor could cause cancer. Step 2: Identify a downstream protein whose malfunction would cause the cell to reproduce continuously : Predict what you would observe if other proteins in the signaling pathway, including KR1-KR3, CDP1, and CDI2, malfunction. This step will enable us to determine whether a malfunction in a protein downstream of the receptor could cause cancer. Step 1: Analyze the signaling pathway to determine the consequence of a malfunction in the receptor. Every protein in a cell is made from instructions contained in a gene . When a carcinogen mutates these instructions, the cell will make a mutant protein whose function could differ from that of the typical protein. Many mutant proteins have a different structure than the typical protein, causing the mutant protein to malfunction within the cell. Imagine that a carcinogen mutates the gene for the protein that functions as the receptor (R1) in the signaling pathway of spotted gliders. The mutated receptor remains active at all times, regardless of whether the signal (SR1) is present. What impact, if any, would this mutation have on the signaling pathway? Could this mutation have caused the tumors that we observed in spotted gliders? Directions : Use the scenario provided above and the signaling pathway in Figure 1.3 to answer questions 15-20. 15. Given the scenario above, select the claim that is best supported by the signaling pathway in Figure 1.3.

a. The concentration of active CDP1 in the mutated cell will be greater than the concentration of active CDP1 in a typical cell. b. The concentration of active CDP1 in the mutated cell will be less than the concentration of active CDP1 in a typical cell. c. The concentration of active CDP1 in the mutated cell will be similar to the concentration of active CDP1 in a typical cell. 16. Explain your answer to the previous question. Your explanation should minimally discuss how you used the signaling pathway in Figure 1.3 to determine whether the concentration of active CDP1 in the mutated cell would differ from the concentration of active CDP1 in a typical cell. ● I believe that the concentration of active CDP1 in the mutated cell will be greater than the concentration of active CPD1 in a typical cell because in a typical cell, CDP1 would be active when the SR1 signal is present. In this case, however, we see that the mutated cell CDP1 is constantly active. Furthermore,we can assume that there will be a higher concentration of active CPD1. 17. Given the scenario above, select the claim that is best supported by the signaling pathway in Figure 1.3. a. The concentration of active CDI2 in the mutated cell will be greater than the concentration of active CDI2 in a typical cell. b. The concentration of active CDI2 in the mutated cell will be less than the concentration of active CDI2 in a typical cell. c. The concentration of active CDI2 in the mutated cell will be similar to the concentration of active CDI2 in a typical cell. 18. Explain your answer to the previous question. Your explanation should minimally discuss how you used the signaling pathway in Figure 1.3 to determine whether the concentration of active CDI2 in the mutated cell would differ from the concentration of active CDI2 in a typical cell. ● The concentration of active CDI2 in the mutated cell will be less than the concentration of active CDI2 in a typical cell because the CDP1 is constantly active now in the mutated gene. When the secondary messengers are active, CDI2 is turned off/inactive. Based on the data, we can conclude that the protein that restricts cell division will also be inactive given all the scenarios where the mutated receptor remains on regardless of the signal. 19. Given the scenario above, select the claim that is best supported by the signaling pathway in Figure 1.3. The mutated cell will reproduce… a. …only in the presence of the signal SR1. b. …only in the absence of the signal SR1.

c. …in the presence or absence of the signal SR1. 20. Explain your answer to the previous question. Your explanation should minimally discuss how you used the signaling pathway in Figure 1.3 to determine whether the presence or absence of the signal SR1 will affect the mutated cells’ reproduction. ● The mutated cell will reproduce regardless of being in the presence or absence of the signaling SR1. Based on the signaling pattern, we know the CDP1 protein is supposed to promote cell division. In this case CDP1 is active with or without a signal that comes from SR1. Based on this info, the mutated cell will reproduce in the presence or absence of the signal SR1.

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Step 2: Identify a downstream protein whose malfunction would cause the cell to reproduce continuously. An active receptor interacts with other proteins in the membrane or cytoplasm. For example, in Figure 1.3 when R1 is activated it activates kinase KR1. These downstream proteins, such as kinases, help to filter, interpret and boost the signal, ultimately influencing how a cell behaves. Thus, a cell may behave unusually when a downstream protein in a signaling pathway malfunctions. In Step 1 we considered the impact that a malfunctioning receptor could have on mutated cells. Could the tumors of spotted gliders have been caused by the malfunction of a downstream protein rather than the receptor? The signaling pathway has five downstream proteins: KR1, KR2, KR3, CDP1 and CDI2. For each of the downstream proteins, predict whether a malfunction would stimulate or inhibit cellular reproduction. Once you have analyzed the effect of a malfunction in each downstream protein, you can decide which protein would likely cause a cell to reproduce continuously if the protein malfunctioned. Directions: Use the signaling pathway in Figure 1.3 to answer questions 21-30. For ease, Figure 1.3 has been provided below. For each of the true false statements, assume the R1 receptor is inactive and assume there is no SR1 signal present. Figure 1.3. The signaling pathway that regulates cell division in spotted gliders.

Upper left: The signaling molecule (SR1) binds to the receptor (R1). Center: When no signaling molecule is bound to the receptor, most proteins in the signaling pathway are inactive, but a protein that represses cell division (CDI2) is active. Right: When a signaling molecule is bound to the receptor, most proteins in the signaling pathway become active. The first three proteins in the pathway (KR1-KR3) are activated by phosphorylation. The protein KR3 inactivates CDI2, which prevents CDI2 from inhibiting cell division. KR3 also activates CDP1, which directly promotes cell division. 21. True or False: If a malfunction caused KR1 to permanently remain in its active state, this would likely cause cell division to increase. a. True b. False 22. Explain your answer to the previous question. Your explanation should minimally discuss how you used the signaling pathway in Figure 1.3 to determine if a malfunction that caused KR1 to permanently remain in its active state would likely cause cell division to increase (or not). ● If the malfunctioning is causing KR1 to permanently remain in its active state, this would likely cause cell division to increase. While viewing the signaling pathway, KR1 is the first of the secondary messengers that will send signals to the other secondary messengers. They then will tell CDP1 to become active, which will promote cell division to occur. Based on this information, malfunction that causes KR1 to permanently remain in its active state will more likely cause cell division to grow. 23. True or False: If a malfunction caused KR2 to permanently remain in its active state, this would likely cause cell division to increase. a. True b. False 24. Explain your answer to the previous question. Your explanation should minimally discuss how you used the signaling pathway in Figure 1.3 to determine if a malfunction that caused KR2 to permanently remain in its active state would likely cause cell division to increase (or not). ● If a malfunction is causing kr2 to permanently ramain in its active state, this would likely cause cell division to increase. Looking at the signaling pathway, KR2 is the second of the secondary messengers (Directly behind) KR1 that will send signals to other third secondary messengers. They will tell CDP1 to become active, which will promote cell division to occur. Based on this information, a malfunction that causes KR2 to permanently remain in its active state will more than likely cause cell division to grow.

25. True or False: If a malfunction caused KR3 to permanently remain in its active state, this would likely cause cell division to increase. a. True b. False 26. Explain your answer to the previous question. Your explanation should minimally discuss how you used the signaling pathway in Figure 1.3 to determine if a malfunction that caused KR3 to permanently remain in its active state would likely cause cell division to increase (or not). ● If a malfunction causes KR3 to remain permanently active, it would likely cause cell division to increase. Based on the signaling pathway in the diagram, the protein KR3 inactivates CDI2, which prevents CDI2 from inhibiting and restricting cell division. KR3 also activates CDP1 which directly promotes cell division. Therefore, if a malfunction caused KR3 to remain permanently inactive, it would cause cell division to increase. 27. True or False: If a malfunction caused CDP1 to permanently remain in its active state, this would likely cause cell division to increase. a. True b. False 28. Explain your answer to the previous question. Your explanation should minimally discuss how you used the signaling pathway in Figure 1.3 to determine if a malfunction that caused CDP1 to permanently remain in its active state would likely cause cell division to increase (or not). ● If a malfunctioning cell is causing CDP1 to remain in its cative state, this will cause cell division to increase. This is because of the signaling pathway that is shown in our scenario. CDP1 is primarily responsible for cell division. If this protein remains active, it will more than likely cause cell division to increase. 29. True or False: If a malfunction caused CDI2 to permanently remain in its active state, this would likely cause cell division to increase. a. True b. False 30. Explain your answer to the previous question. Your explanation should minimally discuss how you used the signaling pathway in Figure 1.3 to determine if a malfunction that caused CDI2 to permanently remain in its active state would likely cause cell division to increase (or not). ● If there was a malfunction occurring in CDI2 and it was permanently active, this would cause cell division to decrease. In the signaling pathway, CDI2 is responsible for inhibiting cell division. If the protein remained active, cell division would decrease and not increase. The rate

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of cellular division would be much lower.

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Lab Instructions_ Cell Biology Act I Mission Memo (Spring A 2024 Onward)

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