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Viruses and Bacteria Table of Contents Viruses Bacteria Viruses, Bacteria, and Your Health Viruses and Bacteria - Viruses What Is a Virus? A virus is a tiny nonliving particle that enters and then reproduces inside a living cell. Virus particles are tiny compared to bacteria. Viruses and Bacteria - Viruses The Structure of Viruses All viruses have two basic parts: a protein coat that protects the virus and an inner core made of genetic material. Some viruses are surrounded by an outer membrane envelope. Viruses and Bacteria - Viruses How Viruses Multiply Active viruses enter cells and immediately begin to multiply, leading to the quick death of the invaded cells. Viruses and Bacteria - Viruses Diameter The diameter of a circle is a line that passes through the center of the circle and has both of its endpoints on the circle. To find the diameter, draw a line like the one shown below. Then use a metric ruler to measure the length of the line. For example, the diameter of a penny is about 1.9 mm. Viruses and Bacteria - Viruses Diameter Practice Problem Measure the diameter of a quarter. 2.4 cm Viruses and Bacteria - Viruses Diameter Practice Problem Measure the diameter of a CD. 12 cm Viruses and Bacteria - Viruses How Viruses Multiply Hidden viruses “hide” for a while inside host cells before becoming active. Viruses and Bacteria - Viruses Active and Hidden Viruses Activity Click the Active Art button to open a browser window and access Active Art about active and hidden viruses. Viruses and Bacteria - Viruses Sequencing As you read, make two flowcharts that show how active and hidden viruses multiply. Put the steps in the process in separate boxes in the flowchart, in the order in which they occur. How Active Viruses Multiply Virus attaches to the surface of a living cell. Virus injects genetic material into cell. Cell produces viral proteins and genetic material. Viruses assemble. Cell bursts, releasing viruses. Viruses and Bacteria - Viruses Sequencing As you read, make two flowcharts that show how active and hidden viruses multiply. Put the steps in the process in separate boxes in the flowchart, in the order in which they occur. How Hidden Viruses Multiply Virus attaches to cell. Virus injects its genetic material. Virus’s genetic material becomes part of cell’s genetic material. Cell produces viral proteins and genetic material. Viruses are assembled. Cell bursts, releasing viruses. Viruses and Bacteria - Viruses Deadly Virus Click the Video button to watch a movie about deadly viruses. Viruses and Bacteria End of Section: Viruses Viruses and Bacteria - Bacteria The Bacterial Cell Bacteria are prokaryotes. The genetic material in the cells is not contained in a nucleus. Viruses and Bacteria - Bacteria Population Explosion Suppose a bacterium reproduces by binary fission every 20 minutes. The new cells survive and reproduce at the same rate. This graph shows how the bacterial population would grow from a single bacterium. Viruses and Bacteria - Bacteria Population Explosion Reading Graphs: What variable is being plotted on the horizontal axis? What is being plotted on the vertical axis? Horizontal axis–time (minutes); vertical axis– number of bacterial cells. Viruses and Bacteria - Bacteria Population Explosion Interpreting Data: According to the graph, how many cells are there after 20 minutes? One hour? Two hours? 2 cells after 20 minutes; 8 cells after one hour; 64 cells after two hours. Viruses and Bacteria - Bacteria Population Explosion Drawing Conclusions: Describe the pattern you see in the way the bacterial population increases over two hours. The number of cells doubles with each division. Viruses and Bacteria - Bacteria Population Explosion Predicting: Do you think the bacterial population will continue to grow at the same rate? Why or why not? Not likely. The bacteria will continue to reproduce at this rate only as long as the conditions are favorable. Viruses and Bacteria - Bacteria Building Vocabulary After you read the section, reread the paragraphs that contain definitions of Key Terms. Use all the information you have learned to write a definition of each Key Term in your own words. Key Terms: bacteria reproduction flagellum asexual endospore pasteurization respiration sexual reproduction cytoplasm binary fission decomposer ribosome conjugation Examples: AnLeeuwenhoek If A Asexual bacterial endospore reproduction cell may ishad a small, also owned ishave a rounded, reproductive one a flagellum, of the thick-walled, high-powered process a long,that microscopes whiplike involves resting cell structure only that in one use forms parent that today, inside helps and heaproduces would cell bacterial tohave move. offspring cell. seen the that single-celled are to organisms the parent. known as bacteria Theidentical During process pasteurization, of breaking food down is food heated to release to a in detail. its Sexual reproduction involves two parents who The region inside cellenough membrane, the energy temperature is called thatrespiration. isthe high to killcalled most harmful combine their genetic material to produce a new cytoplasm, contains material. bacteria changing the taste of the food. Bacteria without reproduce byaagel-like process called binary organism, which differs from both parents. fission, in one cell divides to form identical These bacteria, which liveare in the are twocalled Located in which the cytoplasm tinysoil, structures During a process called conjugation, one bacterium cells. decomposers—organisms thatwhere break proteins down large ribosomes, chemical factories are transfers some of its genetic material to another chemicals produced. in dead organisms into small chemicals. bacterium through a thin, threadlike bridge that joins the two cells. Viruses and Bacteria - Bacteria More on Bacteria Click the PHSchool.com button for an activity about bacteria. Viruses and Bacteria End of Section: Bacteria Viruses and Bacteria - Viruses, Bacteria, and Your Health Common Bacterial Diseases Many bacterial diseases can be cured with antibiotics. Viruses and Bacteria - Viruses, Bacteria, and Your Health Common Viral Diseases Unlike with bacterial diseases, there are currently no medications that can cure viral infections. Viruses and Bacteria - Viruses, Bacteria, and Your Health Using Prior Knowledge Look at the section headings and visuals to see what this section is about. Then write what you already know about diseases caused by viruses and bacteria in a graphic organizer like the one below. As you read, write what you learn. What You Know 1. 2. You can catch a cold from somebody who has one. Some diseases can be treated with medicines. What You Learned 1. 2. You can catch diseases through contact with an infected person, a contaminated object, an infected animal, or an environmental source. Antibiotic resistance results when some bacteria are able to survive in the presence of an antibiotic. Viruses and Bacteria - Viruses, Bacteria, and Your Health Antibiotic Resistance Click the Video button to watch a movie about antibiotic resistance. Viruses and Bacteria - Viruses, Bacteria, and Your Health Links on Infectious Diseases Click the SciLinks button for links on infectious diseases. Viruses and Bacteria End of Section: Viruses, Bacteria, and Your Health Viruses and Bacteria Graphic Organizer Nonliving Can be useful Treated with antibiotics Viruses and Bacteria End of Section: Graphic Organizer