Exam (elaborations) BIOLOGY 101 GIZMO Virus Lytic Cycle Student Exploration Sheet

Exam (elaborations) BIOLOGY 101 GIZMO Virus Lytic Cycle Student Exploration Sheet 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? A computer Virus and a real virus are very similar because theey both duplicate and infect the host in order to harm the host. 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? I felt like i didn't have energy, and I was coughing and Sneezing all the time, most likely because my body was fighting against the virus. 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 virus and a bacterial cell in the image at right. 2. Bacteriophages are viruses that infect bacteria. Based on the diagram at left, label the head, tail, tail fibers, and the strand of nucleic acid in the image at right. Activity A: Lytic cycle Get the Gizmo ready:  If necessary, click Reset ( ). This study source was downloaded by from CourseH on :46:16 GMT -05:00 This study resource was shared via CourseH BIOLOGY 101 GIZMO Virus Lytic Cycle Student Exploration Sheet 2019 The virus injects its nucleic acid into the cell. The nucleic acid uses the cell's ribosomes to make virus proteins. The proteins break up the cell's DNA 2 The virus capsid and tail, now useless, detach from th cell and disintegrate. Inside the cell, the viral nucleic acid takes over and directs the production of new virus proteins and nucleic acid. 3 The virus proteins and nucleic acid assemble into new viruses. 4 Special proteins produced by the viral nucleic acid cause the host bacterial cell to lyse (burst) destroying the cell in the process. The numerous new viruses are now free to infect other cells. 5 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. 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 lytiv bacteriophage viurs attaches itself to a bacteria cell. The virus is a very simple structure, composed if a protein capsid, nucleic acid, and a tail section. ↓ ↓ ↓ ↓ (Activity A continued on next page) This study source was downloaded by from CourseH on :46:16 GMT -05:00 This study resource was shared via CourseH Activity A (continued from previous page) 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? Because now the Virus DNA's is the main DNA inside the cell and its used to produce more viruses off that cell. 3. Describe: How does a virus destroy the host cell’s DNA? It replaces the cell's DNA for the Virus DNA and starts making new viruses from there on. 4. Describe: How are new viruses reproduced? Those viruses g o to othe r cells an d repeat the_ the same process over and over. 5. Think and discuss: Why can’t a virus reproduce on its own? because it doesn't have the necessary structures to reprduce for itself unlike the cells inside the body. 6. Justify: To lyse is to burst apart or explode. Why do you think a virus’s reproduction cycle is called the “lytic cycle”? Becuas after the virus uses the cells structure to reproduce then it explodes out of the cell to go out and reproduce in other cells. Activity B: Spread of infection 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. This study source was downloaded by from CourseH on :46:16 GMT -05:00 This study resource was shared via CourseH Viruses: Increase Infected cells: Increase Uninfected cells: Dicrease 2. Observe: Click Play ( ), and watch the simulation. Describe what you see. One virus entered the organism and infected on cell, then it used that cell to reproduce itself and infect more cells. 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 your predictions? As the process went on the number of viruses and infecteed cells increased and the number of Healthy cells decreased, but when the process finished the number of infected and healthy cells went to 0 and the numbeer of viruses increased to 151. 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. For example, if it took 80 minutes to reach 40 cells and 100 minutes to reach 30 cells, then the time difference is 20 minutes. Number of healthy cells Time (minutes) Amount of time to decrease population by 10 50 0 minutes -- 40 68 minutes 68 30 82 minutes 14 20 101 minutes 19 10 108 minutes 7 (Activity B continued on next page) This study source was downloaded by from CourseH on :46:16 GMT -05:00 This study resource was shared via CourseH Activity B (continued from previous page) 7. Analyze: What trend do you see in the third column of your data table? _ as the number of healthy cells go down the time that it takes to go down decreases as well, which shows that more viruses were duplicated. 8. Explain: How would you explain this trend? The amount of time that it took for a ten cells to get infected went down because there were more viruses after the time passed by. 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? because white blood cells are fighting against the virus, and trying to kill it. B. Sometimes when a virus enters a cell, it becomes dormant for a while. Why might this make it difficult for a doctor to diagnose a viral infection? Becausee the virus hides, and acts as a regular cell so its difficult for the doctors to identify it 10. Extend your thinking: AIDS is one disease caused by a virus infection. The virus attacks immune system cells known as T cells. Based on your observations from the Gizmo, how would you explain the data shown on this graph? The virus attacks the T cells so those infected T cells become useless and the virus count keeps growing, and the cells count goes down because the virus keeps infecting them and killing them. This study source was downloaded by from CourseH on :46:16 GMT -05:00 This study resource was shared via CourseH