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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.
Section 19-1
Interest Grabber
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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.
Section 19-1
Interest Grabber continued
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19–1 BacteriaA. Classifying Prokaryotes
1. Eubacteria2. Archaebacteria
B. Identifying Prokaryotes1. Shapes2. Cell Walls3. Movement
C. Metabolic Diversity1. Heterotrophs2. Autotrophs3. Releasing Energy
Section 19-1
Section Outline
D. Growth and Reproduction1. Binary Fission2. Conjugation3. Spore Formation
E. Importance of Bacteria1. Decomposers2. Nitrogen Fixers3. Human Uses of Bacteria
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Section 19-1
Concept Map
are classified into the kingdoms of
live in harsh environments such as
include a variety of lifestyles such as
Bacteria
Eubacteria Archaebacteria
Infecting large organisms
Thick mudLiving in soilAnimal
digestive tracts
Salty lakes Hot springs
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Peptidoglycan
Cell wall
Cell membrane
Ribosome
Flagellum DNA Pili
Section 19-1
The Structure of a Eubacterium
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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.
Section 19-2
Interest Grabber
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?
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19–2 Viruses
A. What Is a Virus?
B. Viral Infection
1. Lytic Infection
2. Lysogenic Infection
C. Retroviruses
D. Viruses and Living Cells
Section 19-2
Section Outline
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T4 BacteriophageTobacco Mosaic
Virus Influenza Virus
Head
Tail sheath
DNA
Tail fiber
RNACapsid
Surfaceproteins Membrane
envelope
RNA
Capsidproteins
Section 19-2
Figure 19-9 Virus Structures
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Figure 19-10 Lytic and Lysogenic Infections
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Section 19-2
Figure 19-11 Viruses and Cells
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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.
Section 19-3
Interest Grabber
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1. In what ways are bacteria similar to humans?
2. In what ways are bacteria different from humans?
3. How can bacteria be harmful?
Section 19-3
Interest Grabber continued
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Section 19-3
Section Outline
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
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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
Regular dental hygiene
Protection from tick bites
Current tetanus vaccination
Vaccination
Proper food-handling practices
Maintaining good health
Clean water supplies
Disease Pathogen Prevention
Section 19-3
Common Diseases Caused by Bacteria
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Oncogenic viruses
Retrovirus
Adenoviruses
Herpesviruses
Poxviruses
DNA
RNA
DNA
DNA
DNA
Cancer
Cancer, AIDS
Respiratory infections
Chickenpox
Smallpox
Type of Virus Nucleic Acid Disease
Section 19-3
Common Diseases Caused by Viruses
Click the image to play the video segment.
Video
Lytic and Lysogenic Cycles
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.
Go Online
Interest Grabber 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.
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?
Interest Grabber 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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