Under the Microscope

1
Under the Microscope
Interest Grabber
Section 19-1

• 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

• 191 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

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
4
Concept Map
Section 19-1
Bacteria
are classified into the kingdoms of
live in harsh environments such as
include a variety of lifestyles such as
5
Classifying Prokaryotes

• Prokaryotes are unicellular organisms that do NOT
  contain a nucleus.
• Originally 1 Kingdom Monera
• Currently 2 Kingdoms
• Eubacteria
• Archaebacteria

• Eubacteria
• -Larger of the two kingdoms
• -Live almost everywhere
• -Cell wall containing petidoglycan
• -DNA
• Archaebacteria
• -Lives in extreme environments
• -Cell wall that lacks peptidoglycan
• -DNA is more like a eukaryote

Borrelia burgdorferiNelson, ASM MicrobeLibrary
6
The Structure of a Eubacterium
Section 19-1
7
Identifying Prokaryotes Shape
Identifying Prokaryotes (Shape)
Leucothrix mucor Appl. Environ. Microbiol.
551435-1446, 1989

• Bacilli Rod shaped prokaryotes
• Cocci Spherical prokaryotes
• Spirilla Spiral and corkscrew-shaped prokaryotes

Ball-shaped StreptococciSimonson, ASM
MicrobeLibrary
http//www.ucmp.berkeley.edu/bacteria/bacteria.htm
l
8
Identifying Bacteria (Cell Wall)
Identifying Prokaryotes (Cell Wall)

• The chemical nature of bacterial cell walls can
  be studied by means of Gram staining.
• Gram Positive carbohydrate and protein
  molecules outside the cell membrane. (Purple)
• Gram Negative Outer layer of lipid and
  carbohydrate molecules. (Red)

http//www-micro.msb.le.ac.uk/video/Gram.html
9
Identifying Prokaryotes (Movement)

• Some Prokaryotes do not move while others do in
  different ways.
• Using a corkscrew motion to move through a
  medium.
• Using a whip-like tail called a flagellum.
• Moving along a layer of slimelike material that
  they secrete themselves.

http//www-micro.msb.le.ac.uk/video/motility.html
10
Metabolic Diversity

• Heterotrophic prokaryotes
• Chemoheterotrophs - must take in organic
  molecules for both energy and carbon.
• Photoheterotrophs photosynthetic organisms that
  require to take in organic compounds as a carbon
  source.
• Autotrophic prokaryotes
• -Photoautotrophs use light energy to convert
  carbon dioxide and water into carbon compounds
  and oxygen.
• -Chemoautotrophs make organic carbon molecules
  from carbon dioxide, but do not require light.

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Releasing Energy Releasing Energy
Releasing Energy

• Obligate Aerobes require a constant supply of
  oxygen in order to live (cellular respiration)
• Obligate Anaerobes can not survive in the
  presence of oxygen (fermentation).
• Facultative anaerobes can survive with or
  without oxygen (cellular respiration and/or
  fermentation). This allows them to live nearly
  everywhere.

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Growth and Reproduction
http//www.emc.maricopa.edu/faculty/farabee/BIOBK/
BioBookmito.html

• Binary Fission the bacteria replicates its DNA,
  doubles in size and then divides forming two
  bacteria. (Asexual- no recombination or exchange
  of genetic material)
• Conjugation genetic information is exchanged
  through a hollow bridge between two bacterial
  cells. .
• Spore formation when growth conditions are not
  favorable, many bacteria can form an endospore,
  which is a thick internal wall that encloses its
  DNA and cytoplasm. They can remain dormant for
  many years.

http//tidepool.st.usm.edu/crswr/bactconjug.html
http//science.nasa.gov/headlines/y2002/01feb_anth
rax.htm
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Importance of Bacteria

• Decomposers bacteria break down dead matter
  into nitrogen and carbon containing compounds.
  These compounds then can be used by other
  organisms, such as plants. With out bacterial
  decomposers, plant and animal life would not be
  able to survive.
• Nitrogen Fixation (process of changing nitrogen
  gas into ammonia and/or nitrates) bacteria
  change the nitrogen present in the atmosphere
  into a useable nitrogen source.
• Human Uses E. coli help break down food and
  produce vitamins in the large intestines. Yogurt
  tastes tangy, due to an acid produced by a
  bacteria. Other uses include waste removal, gold
  mining, and oil removal.

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What Viruses Mean to You
Interest Grabber
Section 19-2

• 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?
15
Section Outline
Section 19-2

• 192 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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What is a Virus?

• Viruses are particles of nucleic acid, protein,
  and in some cases, lipids.
• Viruses reproduce by infecting living cells.
• Extremely small in size
• Usually cell specific
• A viruss protein coat is called its capsid.
  This capsid enables a virus to enter a host cell.
  The capsid protein tricks the cell and allows
  the DNA/RNA to enter the cell.

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Figure 19-9 Virus Structures
Section 19-2
Tobacco Mosaic Virus
T4 Bacteriophage
Influenza Virus
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Viral Infection

• Lytic Infection
• Virus identifies and attaches itself to a host
  cell. (Infection)
• Genetic material overrides host cells
  activities. Cell is instructed to replicate
  viral genetic material and protein coat.
  (Growth)
• Cell is lysed broken open and new viruses are
  released to infect other cells. This kills the
  host cell.

• Lysogenic Infection
• Virus identifies and attaches itself to a host
  cell.
• The prophage (viral DNA) is enbedded in the
  hosts DNA. The prophage may remain part of the
  DNA of the host cell for many generations before
  becoming active.
• When conditions are right, the virus will enter a
  Lytic cycle similar to Lytic Infection.

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Figure 19-10 Lytic and Lysogenic Infections
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Retrovirus

• A new form of virus has been identified known as
  a retrovirus.
• Retroviruses are RNA viruses which can conduct a
  process known as Reverse Transcription
• In reverse transcription RNA is used to make DNA
  (the reverse of the normal RNA transcription
  process).
• HIV is a retrovirus

http//www.vircolab.com/content/backgrounders/www.
vircolab.com/hiv_virus.gif
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Figure 19-11 Viruses and Cells
Section 19-2
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Bacteria vs. Humans
Interest Grabber
Section 19-3

• Bacteria are all around youin 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.

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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?

24
Section Outline
Section 19-3
193 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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Bacterial Disease in Humans
http//www.orchd.com/TB/WhatTB.asp

• Some bacteria and virus make us sick. These
  pathogens are disease causing agents and can
  infect organisms in two ways.
• Most attack the bodys cells directly. They
  break down the cells and/or tissues for food.
• -Mycobacterium tuberculosis breaks down lung
  tissue
• Several others produce toxins (poisons) that can
  be carried through out the body.

http//www.giantmicrobes.com/images/circles/strept
ococcus.gif
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Germ Theory

• Pasteur, Louis (1860s)
• Pasteur definitively demonstrated that
  microorganisms are present in air but not created
  by air.
• This was critical for refutation of the concept
  of spontaneous generation and the for development
  of germ theory of disease.
• No contamination when air is withheld
• Contamination due to air-borne particles
• Vaccine discoverer

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Preventing Bacterial Disease

• Vaccine is a preparation of a weakened or
  killed pathogen. This gives the organism a
  resistance to the disease by creating antibodies
  for the specific pathogen.
• Antibiotic - a class of substances that kill or
  inhibit the growth of bacteria. Examples are
  penicillin, tetracycline, and fluoroquinolones.
  Originally, antibiotics were derived from natural
  sources, eg, penicillin from molds, but many
  currently used antibiotics are semi-synthetic and
  modified with additions of synthetic chemical
  components. Some scientists reserve the term
  antibiotic for naturally produced substances and
  use antimicrobial to encompass both synthetic and
  natural forms.

www.ucsusa.org/food_and_environment/antibiotic_res
istance/page.cfm
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Common Diseases Caused by Bacteria
Section 19-3
Disease
Pathogen
Prevention
Regular dental hygiene Protection from tick
bites Current tetanus vaccination Vaccination Prop
er food-handling practices Maintaining good
health Clean water supplies
Tooth decay Lyme disease Tetanus Tuberculosis Salm
onella food poisoning Pneumonia Cholera
Streptococcus mutans Borrelia burgdorferi Clostrid
ium tetani Mycobacterium tuberculosis Salmonella
enteritidis Streptococcus pneumoniae Vibrio
cholerae
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Controlling Bacteria

• Sterilization by Heat sterilization destroys
  all bacteria by subjecting them to great heat.
• Disinfectant disinfectants kill pathogenic
  bacteria.
• Antiseptic kills or inhibits the growth of
  microorganisms on the surface of the body.

• Food Storage and Processing
• Refrigeration slows the growth of bacteria.
• Boiling, frying, or steaming sterilizes many
  kinds of food.
• Canning
• Treatment
• Vinegar
• Salt
• Sugar

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Viral Disease in Humans
Polio
Influence

• Viruses can produce disease by disrupting the
  bodys normal equilibrium.
• Viruses attack and destroy cells in the body.
  (foot and mouth)
• Some viruses can cause cancer. Oncogenic Virus
  (Rous sarcoma)
• Can affect plants. (Tobacco mosaic virus)

West Nile
http//images.google.com/imgres?imgurlhttp//i.cn
n. net/cnn/2003/HEALTH/12/02/west.nile.ap/story.we
st.nile. ap.jpgimgrefurlhttp//www.cnn.com/2003/
HEALTH/12/0 2/west.nile.ap/h168w220sz14tbni
dhuoj_f4iP0ln fMtbnh77tbnw102hlenstart1
prev/images3F q3Dwest2Bnile26svnum3D1026hl
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http//www.path.ox.ac.uk/dg/vdisease.html
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Viroids and prions are viruslike particles that
can cause disease.

• Viroids single stranded RNA molecules that have
  no surrounding capsid. They cause disease in
  plants, by disrupting the metabolism of the plant
  cell and stunt its growth.

• Prions protein infectious particles.
• 1st discovered in the 1980s
• Cause disease by producing protein clumps that
  induce normal protein molecules to become prions.
  
• Attacts nervous system
• Mad Cow
• Creutzfeldt-Jakob Disease

http//www.madcowsracing.org/moo.html
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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 Herpesvi
ruses Poxviruses
DNA RNA DNA DNA DNA
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Video
Video
Lytic and Lysogenic Cycles

• Click the image to play the video segment.

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Internet
Go Online

• 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.

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Section 1 Answers
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.

36
Section 2 Answers
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?
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Section 3 Answers
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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