Section 19-1
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Section 19-1 CHAPTER Summary 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

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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

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BACTERIA – Chapter 19

  • How big are they?

  • What are their structures?

  • How do they eat and make energy?

  • How do they reproduce?

  • In general, what role do many bacteria play? (“niche”)

  • What are some of the positive uses of bacteria?

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Living in soil

Infecting large organisms

Thick mud

Animal digestive tracts

Salty lakes

Hot springs

Concept Map

Section 19-1


are classified into the kingdoms of

include a variety of lifestyles such as

live in harsh environments such as

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More species

Found everywhere

Cell walls of peptidoglycan



No peptidoglycan

Different lipids in its membrane

Found in harsh environments

DNA sequences similar to eukaryotes

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  • The domain Archaea

  • Include prokaryotes that do not have peptidoglycan walls

  • 3 major groups:


    Extreme halophiles

    Extreme thermophiles

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  • Methanogens: convert hydrogen and carbon dioxide into methane to generate energy anaerobically. Methanogens are obligate anaerobes: they are killed by oxygen.

  • Methanogens digest cellulose in cow and termite guts. Each cow belches 50 liters of methane a day. A major greenhouse gas.

  • Methanogens are also in swamps, wetlands, and garbage dumps. (Garfield Shopping Mall)

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  • Extreme halophiles. Grow in very salty conditions. Colorful bacteria in seawater evaporation beds, Great Salt Lake.

  • Mostly aerobic metabolism.

  • Some have a form of photosynthesis that uses bacteriorhodopsin, a pigment very similar to the rhodopsin pigment in our eyes. It is also called “purple membrane protein”

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  • Extreme thermophiles. Live at very high temperatures: ocean hydrothermal vents (up to 113o C, which would be boiling except for the high pressure under the ocean), hot springs in Yellowstone National Park.

  • Use sulfur to generate energy just like we use oxygen: donate electrons to sulfur to create hydrogen sulfide. Some generate sulfuric acid instead—they live at very low pHs.

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ProkaryoticvsEukaryoticvsMitochondria and Chloroplasts

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  • Methods for Identifying and classifying microorganisms

    * Morphological characteristics

    * Differential staining

    * Biochemical tests

  • Bergey’s Manual of Systematic Bacteriology-Used to identify microorganisms based on the results of these observations. The “bible” of bacterial identification.

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Basic BacterialShapes

  • Three basic shapes:

  • Coccus

  • Bacillus

  • Spirilum

  • Common Prefixes:

  • Diplo - two

  • Tetra - four

  • Staphylo - cluster

  • Strepto - chain

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Bacterial morphologies (1)

Assorted Shapes

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  • Appendages - flagella, pili

  • Surface layers - capsule, cell wall, cell membrane

  • Cytoplasm - nuclear material, ribosome, cytoplasm

  • Specialized structure - endospore

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Bacterial Cell Wall

  • Gram (+)

    Those made up of peptidoglycan.

    (Appear blue/purple after staining)

  • Gram (-)

    Those with little petidoglycan but a great deal of lipopolysaccharide.

    (Appear pink/red after staining)

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Gram Stain


( - )


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Differential Agar - Mannitol agar

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Capsule or slime layer

  • Many bacteria are able to secrete material that adheres to the bacterial cell

  • It consists of polysaccharide (andsometimes polypeptide) on bacilli. Most of them have only polysaccharide. It is a protective layer that resists host phagocytosis (process of engulfing).

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How do bacteria “breathe”?- Obligate aerobe- Obligate anaerobe- Facultative anaerobes

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Endotoxin VS Exotoxin

  • Exotoxins: Produced inside the bacterium and given off.

  • Endotoxins: Make up the bacterium’s cell wall (some lipopolysaccharides in Gram (-))

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Cytoplasm & Structures

80% water, nucleic acids, proteins, carbohydrates, lipid and inorganic ions etc.

1. Bacterial chromosomes

Single large circular double stranded DNA (no histone proteins)

2. Plasmids

An extra loop of DNA found in some bacteria. Used in genetic engineering.

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Cytoplasm & Structures (cont’d)

3. Ribosome

Site of protein synthesis. (Amino acids linked together)

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Bacterial Reproduction

  • Binary fission

    (What is it?)

  • Conjugation

    (What does it accomplish?)

  • Endospores

    (What is their advantage?)

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Spore Production (endospores)

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Two different stains showing endospores. Closteridium tetani on the right.

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Growth of Bacteria

  • Under ideal conditions, bacteria grow very rapidly: some double in number every 20 minutes.

  • Doubling in number: 1-2-4-8-16-… is exponential growth. It starts off slowly, but once going the number of bacteria increase very rapidly

  • Usually some nutrient runs short, or waste material builds up, and growth ceases. Eventually a die-off occurs, reducing the number of live bacteria.

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“Ideal conditions?”

  • Temperature

  • Food

  • Water

  • No light (or light?)

  • Oxygen (or no oxygen)

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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

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BioEd Online


  • Here is how you can imagine the size of viruses:

    “If a virus was the size of a basketball…”

    • A bacterium would be as large as a city block

    • A grain of sand would be two miles long

    • A person would be 4,000 miles tall

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Tail sheath

Tail fiber





Figure 19-9 Virus Structures

Tobacco Mosaic


Influenza Virus

T4 Bacteriophage

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Nucleic acid


What Are Viruses Made Of?

  • Viruses are composed of nucleic acid, proteins, and sometimes, lipids.

  • *Nucleic acid, which can be either DNA or RNA, encodes the genetic information to make virus copies.

  • *The nucleic acid is surrounded by a protective protein coat, called a capsid.

  • *An outer membranous layer, called an envelope, made of lipid and protein, surrounds the capsid in some viruses..

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into the

Lytic Cycle

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No capsid

Strand of RNA

Can reproduce inside cell


No capsid.

Only a protein (glycoprotein) – that can enter into cells and cause disease

Viroids Prions

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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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Common Diseases Caused by Bacteria

Section 19-3




Tooth decay

Lyme disease



Salmonella food poisoning



Streptococcus mutans

Borrelia burgdorferi

Clostridium tetani

Mycobacterium tuberculosis

Salmonella enteritidis

Streptococcus pneumoniae

Vibrio cholerae

Regular dental hygiene

Protection from tick bites

Current tetanus vaccination


Proper food-handling practices

Maintaining good health

Clean water supplies

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Common Diseases Caused by Viruses

Section 19-3

Type of Virus

Nucleic Acid



Cancer, AIDS

Respiratory infections



Oncogenic viruses










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  • Possesses RNA rather than DNA

  • HIV is a retrovirus

  • Human Immune Deficiency Virus

  • Acquired Immune Deficiency Syndrome

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CD4 Receptor

  • (protein data bank)