Bacteria

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Bacteria Viruses
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Virus Objectives

• What is a virus?
• What is the structure of a typical virus?
• How do viruses reproduce?
• C/C lytic and lysogenic cycles
• What happens to viruses once they infect
• an organism?
• Name some viruses and what they do

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History

• Iwanowski and Beijernick (1890s)
• Worked on Tobacco Mosaic Virus (infects tobacco
  and tomato leaves).
• Creates mosaic pattern on leaves.
• Made a juice of the infected leaves and then put
  this juice through a filter.
• Rubbed the filtered juice onto leaves.
• Still became infected.
• Concluded that whatever these disease causing
  particles were, they were very small (smaller
  than bacteria).
• Named them viruses meaning poison.

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• Stanley (1935)
• Purified TMV into a crystal.
• Living particles dont crystallize therefore,
  viruses are non-living pathogenic (disease
  causing) particles.

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Viruses

• Particles of nucleic acid, protein and sometimes
  a lipid envelope.
• Obligate intracellular parasite (can only
  replicate within a living cell)

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Structure of a virus

• Small 20nm (polio virus) 350nm (small pox
  virus)
• Single type of nucleic acid (RNA or DNA but never
  both)
• Protein coat capsid
• Some have envelopes (made of lipids)outside of
  capsid
• Surface projections made up of lipids for
  attachment onto host cells
• Are specific to their host

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Shapes

• Shapes are
• Rod
• Helical
• Icosahedral (20 sides)

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HIVRetrovirus
Envelope Projections
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Bacteriophage
Capsid
Infect E. coli bacteria Attach with tail fibers
onto cell. Inject nucleic acid into cell
Tail
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The Lytic Cycle

• Get in, replicate and get out to invade other
  host cells
• Virulent (Disease causing)
• The cold, rubella (German measles), mumps

Release
Attachment at Receptor site
Entry
Assembly
Replication
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The Lytic Virus infection
Attaches onto host cell Injects DNA
into host cell Replication of Viral parts
Reassembly of virons
Lysis bursting out
Viruses that reproduce only by the lytic cycle
are called Virulent
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Lysogenic Infection

• Virus embeds its DNA into hosts DNA which is
  replicated with host cells DNA.
• Remains unnoticed for sometimes years
• AIDS, cold sores, chicken pox, hepatitis

Prophage
Attachment
Integration Cell multiplication
Injection of nucleic acid

Prophage remains unnoticed and not transcribed
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Lytic and Lysogenic Cycles
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Viral Diseases

• Measles, Mumps, Rubella, Rabies, the Cold, the
  Flu, Influenza, Hepatitis, AIDS, Chicken pox,
  Small pox, Polio, Yellow fever, Meningititis,
  some cancers, Swine flu
• Vaccines are small doses of either killed,
  altered or live viruses. Body builds up
  antibodies against virus

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Diseases caused by viruses

• AIDS
• The Cold
• Measles
• Mumps
• Rubella
• Chicken pox/Shingles
• Small Pox
• Hepatitis
• SARS
• The Flu
• Ebola
• HPV
• Bird Flu
• Polio

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Polio and the Iron Lung
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The Different forms of Viruses

• Retroviruses AIDS. Contains RNA instead of
  DNA. Goes from RNA to DNA to RNA to protein.
  Normal is DNA to RNA to protein.
• Viroids another disease causing agent but no
  capsid, only the RNA.
• Found only in plants
• Prion viral proteins that cause diseases.
  Scrapie in sheep degrades nervous system. Mad
  Cow disease (Bovine spongiform encephalopathy) in
  cows puts holes into brain.
• In humans, its Creutzfeld-Jakob disease Kuru.

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Bacteria
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Bacterial Objectives

• What are the two bacterial kingdoms/domains? How
  are they different?
• Describe the structure of a typical bacterial
  cell and the 3 main shapes
• How do bacteria reproduce and metabolize?
• Name some common bacterial disease and their
  causative agents.
• How are bacteria important to us?

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• Formally known as Kingdom Monera
• Unicellular,
• Prokaryotic cell (no nucleus or membrane bound
  organelles.
• Have Ribosomes and a cell wall ,
• Single long, circular strand of DNA
• Auto or Heterotrophic

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Kingdom Archaebacteria

• Lack Peptidoglycan in cell wall a sugar/protein
  substance
• Extremophiles
• First organisms to colonize primitive earth

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Kingdom Eubacteria

• Larger of the two kingdoms
• Have Peptidoglycan in cell wall
• 3 basic shapes
• Bacilli Rod shaped. E. coli, Bacillus anthracis

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• Cocci Spherical shaped.
• Staphylococcus aureus, Streptococcus pyogenes
• Strepto Chains Tetra - 4
  Staphylo clusters
• Diplo 2
  
• Spirilla Spiral shaped. Spirochette, Syphilis

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Staining properties

• Groups Eubacteria in two groups
• Gram Staining
• Gram Positive Gram stain purple with Crystal
  violet due to thick layer of peptidoglycan.
  Easier to kill with antibiotics
• Gram Negative Gram stain pink with Safarin.
  Hard to kill with antibiotics due to thin layer
  of peptidoglycan

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Basic Structure
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Endospores

• Produced by Gram (usually Bacillus
  Clostridium)
• Dormant structure to survive adverse conditions
  (heat, cold, dryness).

Bacillus anthracis
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Methods of Respiration

• Obligate aerobic bacteria must have oxygen.
• Streptococcus
• Obligate anaerobes die if oxygen is present.
• Clostridium
• Facultative anaerobes w/ or w/o oxygen.
• E. coli

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Reproduction

• Asexually by binary fission
• Conjugation - Sexual repro method . Two bacteria
  form a conjugation bridge or tube between them.
  DNA is transferred from one bacteria to the other 

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Binary Fission
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Bacteria and Humans

• Pathogens disease causing agents (Pathology
  science of studying diseases)
• Can produce poisonous toxins (poisons) like the
  botulism toxin
• Destroy food crops

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To fight them

• Antibiotics interfere with cell wall or protein
  synthesis. Penicillin, tetracycline
• Bacteria can mutate and become antibiotic
  resistant (often results from overuse of
  antibiotics)

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Helpful Bacteria

1. Bacteria of decay - major decomposers
   (Saprophytes)
2. Symbiosis Nitrogen Fixing bacteria - Convert
   atmospheric N2 to NH3, Rhizobium in root nodules
   of legumes
3. Fermentation Food processing of sour cream,
   yogurt, buttermilk, wine, sauerkraut, pickles,
   cheese
4. Industrial oil eating bacteria, mining gold,
   cleaning up pollutants - Bioremediation
5. Biotechnology

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Diseases caused by bacteria

• Anthrax
• Botulism
• Cholera
• Cavities
• Gonorrhea
• Syphilis
• Tetanus
• Staph Infection (MRSA)
• Food Poisoning
• Lyme Disease
• Diphtheria
• Tuberculosis
• Escherichia coli O157 H7
• Leprosy
• Meningitis
• Strep throat
• Whooping cough (Pertussis)

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Food poisoning

• Results from decay of foods and production of
  toxins
• 33 million people/yr get stomach flu
• Seafood accounts for 20 25 of cases
• 33 of all raw poultry tests for Staphylococcus
• 1 in every 200 eggs has Salmonella

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4 Cs of Food Safety Chill your foods Cook your
food to the proper temperature Clean food and
cooking surfaces Combat Cross Contamination
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Antibacterial Agents

• Antibiotics organic substance that inhibits
  growth in/on living material. Penicillin
• Disinfectants inhibits growth on a non-living
  surface bleach, ammonia
• Antiseptics inhibits growth on a living surface
  alcohol, hydrogen peroxide
• Sterilization high heat or chemicals that kills
  bacteria

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Antimicrobial agents

• Disinfectants
• 1 Bleach
• 2 Ammonia
• 3 409
• 4 Sterile water

• Antiseptics
• 1 Hand gel
• 2 Iodine
• 3 Alcohol
• 4 Sterile water

• Bacteria (indicate which on you have on your lab)
• Bacillus cereus
• E. coli
• Serratia marcescens

• Antibiotics
• 1 Streptomycin
• 2 Erythromycin
• 3 Tetracycline
• 4 Sterile water

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Disinfectant CC
Antibiotic CC
Antiseptic CC