LS 204 Microbiology Chapter 7

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LS 204 Microbiology Chapter 7
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Student Learning Outcomes

• 1. Name some organisms that are microorganisms
• 2. Explain the importance of microorganisms to
  our everyday lives
• 3. Describe the importance of and differences
  between viruses, viroids, and prions
• 4. Discuss why it is important to understand the
  growth requirements, metabolism, and genetics of
  bacteria
• 5. Explain how microbes cause disease and how we
  control them, both inside and outside of the body

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Questions starting

• What sorts of organisms would be called
  microorganisms give examples
• What are some ways we benefit from microbes?
• What is a virus?
• How do bacteria divide?
• What are some ways the human body defends itself
  against disease?

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Examples of microorganisms of 3 Domains (Fig.
7.1)

• Bacteria Archaea Eukarya

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Example microorganisms of the three Domains

• Domain Archaea prokaryotes extremophiles
• Halobacterium Pyrococcus
• No human pathogens many unusual metabolic
  patterns
• Domain Bacteria prokaryotes
• Escherichia coli, Staphylococcus aureus
  Bacillus anthracis
• Beneficial organisms and human pathogens
• also unusual metabolic patterns
• Domain Eukarya
• Kingdom Protista pathogens like
  Amoeba, Trypanosoma,
• Kingdom Fungi pathogens include yeast like
  Candida
• Kingdom Animalia worms include
  Schistosoma
• Kingdom Plantae algae like Chlamydomonas

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Importance of microorganisms

• Pathogens cause disease in humans, other
  organisms
• Beneficial organisms
• cyanobacteria and algae in oceans do
  photosynthesis and produce sugar and oxygen
• fungi and Bacteria recycle waste products,
  organic molecules, oil spill
• fungi and Bacteria produce food and drinks
  (yoghurt, beer, wine)
• normal microbiota microbes on our skin,
  digestive system that protect from pathogens

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Naming microbes

• Bacteria Domain Bacteria
• bacteria prokaryotes, includes Domain Archaea
• 1 bacterium, 2 bacteria
• Binomial nomenclature Species genus
• ex. Escherichia coli
• Spell out genus first time its used,
• Afterwards, can abbreviate E. coli
• Write names in italics

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Hierarchy in Domain Bacteria

• The groupings help understand shared
  characteristics, antibiotics that will kill them
• Ex. E. coli is Domain Bacteria, Phylum
  Proteobacteria Family Enterobacteriaceae
• Family includes other intestinal inhabitants and
  pathogen genera such as Salmonella, Enterobacter,
  Shigella)

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Names can reflect shapes, sizes, arrangement of
cells

• Coccus (cocci plural) round
• Bacillus (bacilli) rod
• Spirilla spiral-shaped
• Strepto chains
• Staphylo clusters
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• Diplo- two

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Names can indicate properties

• Escherichia coli Eponym for Dr. Escher coli
  for colon
• Micrococcus roseus small red circles
• Mycobacterium tuberculosis
• waxy cell walls, causes tuberculosis (tubercles
  in lungs)
• Streptococcus pneumonia
• round cells in chains, causes pneumonia
• Bacillus megaterium very large rod-shaped
  organism
• Thiobacillus rod-shaped organism that eats
  sulfur

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More microbes Viruses, Viroids, Prions
HPV

• Not considered living since not cells,
• lack ability to reproduce on own
• (use host resources).
• Virus (Fig. 7.4) has nucleic acid (DNA OR RNA)
  wrapped in protein coat
• Some also have envelope
• (made of hosts membrane
• with viral proteins)
• Bacteriophages infect bacteria
• Animal viruses infect animals

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Virus examples
Shapes of virus capsids
herpesvirus
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Virus quantification

• Plaque assay grow viruses on lawn of
  susceptible host cells
• Infection of host cell, replication and
  infection of adjacent cells -gt hole or plaque

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Virus life cycle (Fig. 7.4)

• Attachment specific molecules on virus and
  receptors on host
• Penetration all or some of virus enters
• Uncoating protein coat removed
• Biosynthesis of viral nucleic acids and
  proteins
• mRNA -gt proteins using host ribosomes
• DNA or RNA of genome is reproduced
• Release virus breaks out of cell or buds
  through membrane

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Virus life cycle (Fig. 7.4)

• Herpesvirus
• A DNA virus

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Retrovirus life cycle (Fig. 7.4)

• HIV (Human immunodeficiency virus)
• A retrovirus RNA genome, converts to DNA

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• Viroid
• nucleic acid only some plant diseases
• Prions only protein animal diseases
• Spongiform encephalopathy (Mad Cow disease,
  elk wasting disease) Creutzfeld-Jacob disease
  (CJD)

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Examples of microorganisms of 3 Domains (Fig.
7.1)

• Bacteria Archaea Eukarya

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How bacteria work tiny factories of only 1 cell
compartment

• Growth and nutrition
• Divide by binary fission
• (Fig. 7.5) 1 cell -gt2 cells -gt 4 cells
• Many different metabolic,
• nutrition patterns
• more diverse than eukaryotes
• Latin terms refer to metabolic patterns

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How bacteria work tiny factories of only 1 cell
compartment
cyanobacteria

• Producers include Photoautotrophs
• (photosynthesis,
• use CO2 H2O to make sugars O2)
• Human pathogens are mostly Mesophiles
• (grow at middle temperatures)
• Some bacteria are thermophiles (high
  temperatures)
• Some bacteria are psychrophiles (low
  temperatures)

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• Oxygen requirements
• obligate aerobes (skin, lungs)
• Pseudomonas aeruginosa
• facultative anaerobes (gut)
• Escherichia coli
• obligate anaerobes (puncture wound)
• Clostridium tetani

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• Metabolism similar to eukaryotes, especially for
  pathogens, but only 1 compartment
• Catabolism to take apart molecules and gain ATP,
  building blocks
• Anabolism uses ATP and small molecules to build
  macromolecules

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Typical metabolism

• Glycolysis 6C sugar (glucose) -gt to 3-C
  pyruvate ATP NADH (e- carriers)
• occurs in cytoplasm of bacteria and eukaryotes
• Krebs cycle (citric acid cycle) 3-C pyruvate -gt
  CO2 ATP NADH FADH2
• Electron transport chain (aerobic respiration)
• NADH FADH2 O2 -gt lots of ATP H2O NAD
  FAD
• Occurs in cytoplasm of bacteria
• mitochondria of eukaryotes

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Metabolism cont.

• Fermentation alternative path that does not
  require oxygen occurs in cytoplasm
• Pyruvate -gt an organic molecule a low energy
  path that recycles the NADH
• Yeast make alcohol CO2 (muscle cells lactic
  acid)
• Bacteria make lactic acid, butyric acid, other
  products
• (Fig. 7.6 concept map of relationships of
  pathways)

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Microbial GeneticsDNA -gt RNA -gt protein
(Fig. 7.7)

• Transcription is
• DNA copied into
• rRNA, tRNA or mRNA
• Translation is
• synthesis of protein
• from mRNA
• on the ribosome

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Examples of microorganisms of 3 Domains (Fig.
7.1)

• Bacteria Archaea Eukarya

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Bacterial gene transfer

• Bacteria can transfer some genes from one to
  another (even between species) (Fig. 7.8)
• Transformation piece of DNA can go into another
  cell
• Transduction piece of bacterial DNA packaged in
  bacteriophage coat goes into other cell
• Conjugation two bacteria attach and one donates
  copy of some genes
• Antibiotic-resistant bacteria can transfer
• these genes to other bacteria

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Bacterial gene transfermethods
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Microbial control how we control them.

• Physical and chemical agents
• Disinfectants
• Sterilants (gas, autoclave)
• Sanitizers
• Radiation
• Chemotherapeutics (antibiotics) compounds
  taken inside us to kill them

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Principles of disease

• Each pathogen has its niche temperature,
  humidity, cell type, oxygen
• Epidemiology study of epidemics, or sudden
  large numbers of cases of disease in population.
• Epidemiologists look for patterns of disease,
  moniter numbers
• Note Latin terms, name of disease for body part
  
• meningitis inflammation of meninges
• bacteremia bacteria in the blood system

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Defenders against disease (Table 7.9)

• Innate immunity (nonspecific)
• First line intact skin,
• mucus membranes,
• normal microbiota
• Second line
• natural killer cells
• phagocytic white blood cells,
• inflammation, fever

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Adaptive (specific) immunity

• Specialized lymphocytes
• T cells and B cells
• Antibodies produced by B cells
• circulate in blood stream
• Antibodies recognize
• specific antigens (structures)
• on the pathogen
• Vaccines stimulate
• production of memory
• T cells and B cells
• to defend future infection