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Name: Elianna Fernandez Date: 07-26-2022 Student Exploration: Virus Lytic Cycle Directions: Follow the instructions to go through the simulation. Respond to the questions andprompts in the orange boxes. Vocabulary: bacteriophage, capsid, host cell, lyse, lytic cycle, virus Prior Knowledge Questions (Do these BEFORE using the Gizmo .) 1. A computer virus is a program that can copy itself and infect a computer without the permission of the owner. How do you think a computer virus compares to a real virus? The computer virus can come from another place, such as a website and is unwanted by the owner. 2. Have you ever been infected with a virus, such as the cold virus or flu virus? Yes 3. If so, how did the virus affect you? made me unwell, therefore I was unable to engage in mytypical activities. Gizmo Warm-up A virus is a microscopic particle that can infect a cell. Viruses are primarily composed of a protein coat, called a capsid , and nucleic acid. In the Virus Lytic Cycle Gizmo™, you will learn how a virus infects a cell and uses the cell to produce more viruses. 1. Viruses are extremely small. A typical virus is about 100 times smaller than a single cell, such as a bacterium. Label the virusand a bacterial cell in the image at right. 2. Bacteriophages are viruses that infect bacteria. Based on thediagram at left, label the head, tail,tail fibers, and the strand of nucleicacid in the image at right. Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved
Activity A: Lytic cycle Get the Gizmo ready: ● If necessary, click Reset ( ). Introduction: Unlike living organisms, viruses cannot reproduce on their own. Instead, viruses infect host cells , taking over the cell’s machinery to produce more viruses. This process is called the lytic cycle . Question: What are the steps of the lytic cycle? 1. 75.Observe: Use the navigation arrows on the DESCRIPTION tab to read about the stages of the lytic cycle. Using your own words, summarize each step of the cycle. Step Summary 1 A lytic virus integrates with the bacterial cell. ↓ 2 The virus injects the cell with its nucleic acid. ↓ 3 The virus capsid and tail, now useless, detach from the cell anddisintegrate ↓ 4 New viruses are created when the virus's proteins and nucleic acidcombine. ↓ 5 The cell ruptured, infecting neighboring cells with fresh viruses. Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved
2. Analyze: The yellow ring inside the bacterial cell represents the bacterial DNA. Why does this structure disappear by step 3 of the lytic cycle? Since the virus controls the cell, the DNA is not in charge. 3. Describe: How does a virus destroy the host cell’s DNA? The virus produces proteins that degrade DNA. 4. Describe: How are new viruses reproduced? The viruses spread to other cells as the cell bursts (STEP 5). 5. Think and discuss: Why can’t a virus reproduce on its own? Because they are not actually living organisms 6. Justify: To lyse is to burst apart or explode. Why do you think a virus’s reproduction cycle is called the “lytic cycle”? After the cells explode, more viruses spread. Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved
Activity B: Spread ofinfection Get the Gizmo ready: ● If necessary, click Reset . Question: How does a viral infection spread? 1. Predict: Suppose that a virus infects a small population of bacteria. Predict how the numbers of viruses, infected cells, and uninfected cells will change as the infection progresses. On the blanks below, write increase, decrease, or stay the same . Viruses: Increase Infectedcells: Increase Uninfected cells Decrease 2. Observe: Click Play ( ), and watch the simulation. Describe what you see. A cell is taken over by the viruses, which then rupture it and propagate it. 3. Test: Click Reset , and Select the BAR CHART tab. Turn on Show numerical values . Click Play , and watch each bar as the simulation runs. What do you notice, and how does this compare to yourpredictions? They match my predictions exactly. 4. Record data: Select the TABLE tab, and use the data to complete the second column of the table below. To complete each cell in the third column, subtract the previous time value from the current time value. Forexample, if it took 80 minutes to reach 40 cells and 100 minutes to reach 30 cells, then the time differenceis 20 minutes. Number of healthy cells Time (minutes) Amount of time to decrease population by 10 50 0 minutes -- 40 10 minutes 30 30 20 minutes 10 20 30 minutes -10 10 40 minutes -30 Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved
7. Analyze: What trend do you see in the third column of your data table? The time difference gets smaller 8. Explain: How would you explain this trend? Because more and more viruses are beingcreated, the time required for it to happendecreases. 9. Interpret: Select the GRAPH tab. Run the Gizmo again, and observe what happens in the SIMULATION pane when the graph shows a decrease in the viruses’ population size. A. Why does the number of viruses sometimes increase and sometimes decrease? Some are killed or do notsurvive B. Sometimes when a virus enters a cell, it becomes dormant for a while. Why might this make it difficult for adoctor to diagnose a viral infection? It could mutate 10. Extend your thinking: AIDS is one disease caused by a virus infection. The virus attacks immune system cells known as Tcells. Based on your observations from the Gizmo, how would youexplain the data shown on the graph? That as time increases, the amount of time a person hasto live decreases Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved
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Virus Lytic Cycle Gizmo Answer Key