Welcome to Biolgoy 3: General Microbiology

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Welcome to Biolgoy 3 General Microbiology

• Spring 2007
• Carla DiGennaro

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The Microbial World

• Spontaneous generation
• Scientific method
• Microbes and us
• Microbial diversity and classification
• Nomenclature
• Size

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What are microbes?

• Bacteria
• Viruses
• Protozoa
• Algae
• Fungi (some visible with naked eye)
• Some multicellular parasites helminths (visible
  with naked eye)

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Fields of Microbiology
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Spontaneous Generation vs. Francesco Redi

• Difficult to disprove
• 1600s

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Lazzaro Spallanzanis Experiments

• Earlier experimenters may not have heated vials
  sufficiently or sealed them tightly
• Microorganisms in the air can contaminate
  experiments
• Spontaneous generation of microorganisms does not
  occur

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Louis Pasteurs Experiments

• 1861 Demonstrated that air contains
  microorganisms by filtering air through a cotton
  plug

Figure 1.12
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The Scientific Method
Observation
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Experimental data support hypothesis
Accepthypothesis
Theory or law
Question
Repeat
2
3
Rejecthypothesis
Hypothesis
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Experiment
Observations
Experimental data do not support hypothesis
Modifyhypothesis
Modified hypothesis
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Controls and Experimental Samples

• Positive () Controls
• Negative (-) Controls
• Samples

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Proper controls

• Do the experiment ? look for the effect or lack
  of effect
• Controls
• If you get an effect (-) control ?
• If you get no effect () control ?

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What is a scientific THEORY?

• Theory
• Explanation supported by all available evidence
  (no contradicting evidence)
• If necessary, a theory will be modified

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Pasteurs Experiments on Pasteurization
Figure 1.14
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Pasteurs Experiments on Pasteurization
Figure 1.14 (cont.)
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Microbes and Us

• 1014 cells in human body
• 10 are cells of human origin
• 90 are commensal flora

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Cant live with em, cant live without em

• Viruses have killed more people than war
• BUT, life as we know it could not exist without
  microbes
• Microbes are diverse in every way

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We need them

• Bacteria convert into a
  form plants can use
• Microbes are primarily responsible for
  replenishing
• Microbes help break down materials
• indispensable role in
  cleaning sewage and wastewater
• live in digestive
  tracts of ruminants like cattle, sheep and deer

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We use them

• application of
  biology to solve practical problems and produce
  economically useful products
• Yeast helps make bread and beer (yum!)
• Bacteria help make yogurt, cheese and buttermilk
  (yum again!)

• the use of living
  organisms to degrade environmental pollution
• Assist in cleanup of oil spills
• Assist in treatment of radioactive waste
• Bacteria can destroy dangerous chemical
  pollutants
• A bacterium that can live on TNT? Thats right!

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Genetic Engineering
We can introduce genes from one organism into an
unrelated organism ?

• Produce medically important products
• Engineer plants
• Transfer antibody-eliciting genes into plants
• Gene therapy
• Produce vaccines

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They can kill us

• 1918-1919 more Americans killed by influenza than
  WWI, WWII, Korean War and Vietnam War combined!
• Where did this flu come from?
• Can we overcome?

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Worldwide Flu Epidemic 1910s
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Small Pox Eradicated worldwide 1980
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Polio Worldwide eradication soon?
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SARS (severe acute respiratory syndrome) a
recently emerging viral disease
(a)
(b)
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Emerging Viruses Hantavirus and Ebola Virus
Hantavirus
Ebola Virus
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Emerging Viruses Avian Flu
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Emerging Diseases!

• Diseases
• Change in infectious agents allows them access to
  new hosts
• Changing lifestyles bring new opportunities for
  infectious agents

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Chronic Diseases Caused by Bacteria

• Illnesses thought be result from other causes now
  shown to be caused by microbes
• thought be
  caused by diet, stress ? responsive to
  antibiotics
• known to be
  caused by a worm ? worm must be carrying a
  specific bacterium which causes disease

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Kochs Postulates

• The suspected causative agent must be found in
  every case of the disease and be absent from
  healthy hosts.
• The agent must be isolated and grown outside the
  host.
• When the agent is introduced to a healthy,
  susceptible host, the host must get the disease.
• The same agent must be re-isolated from the
  diseased experimental host.

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How are living organisms classified?

• Domain ? Kingdom ? Phylum/Division ? Class ?
  Order ? Family ? Genus ? species

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Linnaeuss Classification Scheme
Figure 4.25.1
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Linnaeuss Classification Scheme
Figure 4.25.2
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Classifications of Life

• Where does your average house cat fit into the
  grand scheme of life?
• Domain Eukaryota
• Kingdom Animalia
• Phylum Chordata
• Subphylum Vertebrata
• Class Mammalia
• Order Carnivora
• Family Felidae
• Genus Felis
• Species silvestris

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Nomenclature

• Genus species Escherichia coli
• or Homo sapiens
• Genus name may be abbreviated to single, capital
  letter E. coli
• Members of a species are similar to eachother,
  but
• Minor differences may result in organisms
  designated as a different strain E. coli strain
  B

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The Domains of Life

• Eukarya true
  nucleus
• Helminths, algae, fungi and protozoa
• Some may have
• Membrane-bound nucleus and organelles

• Bacteria
  pre-nucleus
• No membrane-bound nucleus or organelles
• DNA stored in region
• Cells may be surrounded

• Archaea Prokaryotes pre-nucleus
• No membrane-bound nucleus or organelles
• DNA stored in region -

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Prokaryotes

• Archaea
• Same size, shape and appearance as bacteria
• May have cell walls
• Ability to grow in extreme environments

• Bacteria
• Specific shapes rod-shaped, spherical, spiral
• Most have rigid cell walls made of
• Multiply by
• Many can move using appendages extending from
  cell -

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Prokaryotes
Prokaryotes
Archaea - Extreme Environment!
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Eukaryotic Microorganisms

• Algae
• All contain can use light
  as a source of energy
• Rigid cell walls made of
• May use flagella for movement different from
  prokaryotic flagella
• Protozoa
• Most groups are motile may have flagella or
  cilia
• No
• Fungi
• Gain energy from organic materials
• Rigid cell wall made of
• Parsitic Worms
• Derive nutrients from host organism ? cause
  disease in humans
• No

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Eukaryotic Microorganisms

• Single-celled or
  multicellular
• All contain can
  use light as a source of energy
• Rigid cell walls made of
• May use flagella for movement different from
  prokaryotic flagella
• Single-celled
• Most groups are motile may have flagella or
  cilia
• No cell wall
• Single-celled or
  multicellular
• Gain energy from organic materials
• Rigid cell wall made of
• 
  Multicellular
• Derive nutrients from host organism ? cause
  disease in humans
• No cell wall

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Eukaryotic Microorganisms Protists
Protozoa
Algae
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Eukaryotic Microorganisms Fungi
Yeast
Mold
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Eukaryotic Microorganisms Parasitic Worms
Figure 1.8
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Viruses and Prions
Non-living infectious agents

• nucleic acid (RNA or DNA)
  surrounded by protective protein coat
• Reproduce by
• All forms of life may be infected by viruses
• Viruses usually kill infected cells but some may
  exist harmoniously with host

• protein only
• Misfolded protein causes other proteins to misfold

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Viruses and Prions
Viruses
Prions
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How big is micro?
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Metric Conversions

• Think of microbial size in terms of
• 1meter 103 mm
• 1 mm 0.001 m
• 1meter 106 µm
• 1 cm 0.000001 m
• 1meter 109 nm
• 1 nm 0.000000001 m

1 m
1,000 mm
1,000,000 µm
1,000,000,000 nm