Under the Microscope

1. Interest Grabber Section 19-1 Under the Microscope • Microorganisms are living things that can only be seen through a microscope. Imagine that you have just discovered a new microorganism. The first thing that you want to do is to tell the scientific community all about your new discovery.

2. Interest Grabber continued Section 19-1 • 1. Describe your microorganism in detail. • 2. Describe its habitat. • 3. Classify your microorganism by giving it a genus and species based on its characteristics.

3. Section Outline Section 19-1 D. Growth and Reproduction 1. Binary Fission 2. Conjugation 3. Spore Formation E. Importance of Bacteria 1. Decomposers 2. Nitrogen Fixers 3. Human Uses of Bacteria • 19–1 Bacteria A. Classifying Prokaryotes 1. Eubacteria 2. Archaebacteria B. Identifying Prokaryotes 1. Shapes 2. Cell Walls 3. Movement C. Metabolic Diversity 1. Heterotrophs 2. Autotrophs 3. Releasing Energy

4. Eubacteria Archaebacteria Living in soil Infecting large organisms Thick mud Animal digestive tracts Salty lakes Hot springs Concept Map Section 19-1 Bacteria are classified into the kingdoms of include a variety of lifestyles such as live in harsh environments such as

5. Ribosome Cell wall Cell membrane Peptidoglycan Pili Flagellum DNA The Structure of a Eubacterium Section 19-1

6. Interest Grabber Section 19-2 What Viruses Mean to You • If you have ever had a cold, you are probably familiar with the word virus. It is a word that makes most people frown. 1. What do you think of when you hear the word virus? Make a list of all the words you can think of that relate to viruses. 2. What are two things that you would like to find out about viruses?

7. Section Outline Section 19-2 • 19–2 Viruses A. What Is a Virus? B. Viral Infection 1. Lytic Infection 2. Lysogenic Infection C. Retroviruses D. Viruses and Living Cells

8. RNA DNA Head RNA Capsid Capsid proteins Tail sheath Tail fiber Surface proteins Membrane envelope Figure 19-9 Virus Structures Section 19-2 Tobacco Mosaic Virus T4 Bacteriophage Influenza Virus

9. Figure 19-10 Lytic and Lysogenic Infections

10. Figure 19-11 Viruses and Cells Section 19-2

11. Interest Grabber Section 19-3 Bacteria vs. Humans • Bacteria are all around you—in the air you breathe, under your feet, on your skin, and even in your body! They may be tiny, but they can still have an impact on your life. • Use what you already know about bacteria to answer these questions.

12. Interest Grabber continued Section 19-3 • 1. In what ways are bacteria similar to humans? • 2. In what ways are bacteria different from humans? • 3. How can bacteria be harmful?

13. Section Outline Section 19-3 • 19–3 Diseases Caused by Bacteria and Viruses A. Bacterial Disease in Humans 1. Using Cells for Food 2. Releasing Toxins 3. Preventing Bacterial Disease B. Bacterial Disease in Animals C. Controlling Bacteria 1. Sterilization by Heat 2. Disinfectants 3. Food Storage and Processing D. Viral Disease in Humans E. Viral Disease in Animals F. Viral Disease in Plants G. Viroids and Prions 1. Viroids 2. Prions

14. Common Diseases Caused by Bacteria Section 19-3 Disease Pathogen Prevention Regular dental hygiene Protection from tick bites Current tetanus vaccination Vaccination Proper food-handling practices Maintaining good health Clean water supplies Tooth decay Lyme disease Tetanus Tuberculosis Salmonella food poisoning Pneumonia Cholera Streptococcus mutans Borrelia burgdorferi Clostridium tetani Mycobacterium tuberculosis Salmonella enteritidis Streptococcus pneumoniae Vibrio cholerae

15. Common Diseases Caused by Viruses Section 19-3 Type of Virus Nucleic Acid Disease Cancer Cancer, AIDS Respiratory infections Chickenpox Smallpox Oncogenic viruses Retrovirus Adenoviruses Herpesviruses Poxviruses DNA RNA DNA DNA DNA

16. Video Lytic and Lysogenic Cycles Video • Click the image to play the video segment.

17. Go Online Internet • The latest discoveries in microorganisms and viruses • Links from the authors on smallpox vaccinations • Career links on epidemiologists • Interactive test • Articles on bacteria and viruses • For links on bacteria, go to www.SciLinks.org and enter the Web Code as follows: cbn-6191. • For links on the lytic cycle, go to www.SciLinks.org and enter Web Code as follows: cbn-6192.

18. Interest Grabber Answers Section 1 Answers • 1. Describe your microorganism in detail. • Students should describe the appearance of their imaginary organism. A possible answer might include its color and shape. • 2. Describe its habitat. • Students should describe whether it lives in water, soil, or another organism; if it is a plant or animal; and how it gets its energy. • 3. Classify your microorganism by giving it a genus and species based on its characteristics. • Students should specify a name for their organism.

19. Interest Grabber Answers 1. What do you think of when you hear the word virus? Make a list of all the words you can think of that relate to viruses. Possible answers: disease, sickness, AIDS virus, infection, microscopic, vaccines, flu, cold 2. What are two things that you would like to find out about viruses? Possible answers: How are viruses related to bacteria? How do viruses cause disease? How do viruses reproduce? How do viruses spread from person to person? Section 2 Answers

20. Interest Grabber Answers Section 3 Answers • 1. In what ways are bacteria similar to humans? • Like humans, bacteria are alive, and some can move. Both obtain energy, exchange gases, grow, and reproduce. • 2. In what ways are bacteria different from humans? • Unlike humans, bacteria are extremely small; some can live in harsher environments and without oxygen; some bacteria use sunlight to produce their own food. • 3. How can bacteria be harmful? • Bacteria cause diseases, release poisonous chemicals, and compete with humans for food.

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