Chapter 23 24 Bacteria

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Chapter 23 - 24 Bacteria Viruses
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How are bacteria classified?

• Domain Archaea
• Kingdom Archaebacteria
• Lack Peptidoglycan (protein
  carbohydrate) in cell wall
• Extremophiles -
• Halophiles (love salt),
• Methanogens (convert H2 CO2 into methane gas),
• Thermoacidophiles (love acidic, hot environments)
• First organisms to colonize primitive earth

Mouth of a geyser
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Domain BacteriaKingdom Eubacteria

• Eu True
• 3 basic shapes
• Bacilli rod shaped. E. coli, Bacillus
  anthracis
• Cocci spherical shaped. Staphylococcus aureus,
  Streptococcus pyogenes
• Spirilla spiral shaped. Spirochette, Syphilis

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Staining properties

• Groups Eubacteria in two groups
• 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

Gram Positive Gram Negative
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Basic Structure

• Cell Wall,
• Plasma membrane
• Ribosomes
• Circular DNA
• Pili (hairs) for adherence to host cells
• Flagella (protein) for movement, capsule (made of
  polysaccharides) for attachment.

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Endospores

• Produced by Gram (usually Bacillus
  Clostridium)
• Dormant structure to survive adverse conditions
  (heat, cold, dryness). Vegetative cell (2N), not
  reproductive

Bacillus anthracis
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Methods of Respiration

• Obligate aerobic bacteria must have oxygen
  (tuberculosis bacteria)
• Obligate anaerobes die if oxygen is present
  (tetanus bacteria that causes lockjaw)
• Facultative anaerobes do not need oxygen, but
  dont die if oxygen is present (E. coli)
• Anaerobes carry on fermentation, while aerobes
  carry on cellular respiration 

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Nutrition

• Heterotrophic or autotrophic
• Saprophytes feed of dead, decaying material
• Autotrophes capable of making their own food,
  photoautotroph photosynthesize, or
  chemoautotrophs oxidize inorganic compounds to
  produce energy (ammonia (NH3) to form nitrite
  (NO2) to get energy

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Reproduction

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

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Binary Fission
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Transformation

• Bacteria pick up pieces of DNA from other dead
  bacterial cells
• New bacterium is genetically different from
  original

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Bacteria and Humans

• Pathogens disease causing agents (Pathology
  science of studying diseases)
• Can produce poisonous toxins (poisons)
• Endotoxins are made of lipids carbohydrates by
  Gram - bacteria released after the bacteria die
  (cause high fever, circulatory vessel damage) E.
  coli  
• Exotoxins are made of protein by Gram
  bacteria . Secreted into environment.
  Clostridium tetani

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To fight them

• Antibiotics interfere with cellular functions
  (Penicillin interferes with synthesis of the cell
  wall tetracycline interferes with protein
  synthesis)
• Some antibiotics are made by bacteria or fungi
• Broad-spectrum antibiotics affect a wide variety
  of organisms
• Bacteria can mutate and become antibiotic
  resistant (often results from overuse of
  antibiotics)

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Helpful Bacteria

• Bacteria of decay
• Nitrogen fixing bacteria (Legumes)
• Fermentation of milk products sour cream,
  yogurt, buttermilk
• Production of cheese
• Fermentation to produce wine, sauerkraut, pickles
• Mining and oil spill cleanup
• 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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Chapter 24 Viruses
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Stanley (1935)

• Crystallized tobacco mosaic virus.
• Living cells dont form crystals
• Named them virus meaning Poison

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Living or non-living?

• Neither!
• Its a non-living pathogenic particle made of a
  protein coat a nucleic acid

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• A virion a single virus particle
• - Small - 20 nm (polio virus) - 350 nm (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 glycoproteins
  for attachment onto host cells - Are
  specific to their host

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Virus Structure

• Icosahedral
• 20 triangular faces Polio, herpes, chicken
  pox, cancer, AIDs, hepatitis, Respiratory
  infections (the cold)Helical TMV, measles,
  rabies, influenza
• Brick shaped small pox, cowpox
• Helical - TMV

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• Viruses are classified by their shape and
  structure
• If it contains DNA
• May produce RNA to make more viral proteins in
  host cell
• Join with hosts DNA to direct the production of
  virions (viral particles)
• If it contains RNA
• Retroviruses such as HIV. Viral RNA uses
  hosts ribosomes for viral protein synthesis
• Reverse transcriptase viral enzyme that uses
  RNA as template to make DNA. Then DNA integrates
  into host DNA and then when triggered, normal
  transcription occurs with the production of RNA
  and translation to produce new viruses. RNA to
  DNA to RNA to protein. Normal is DNA to RNA to
  protein.

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Human Immunodeficiency Virus (HIV)
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• Viroids another disease causing agent but no
  capsid, only the RNA. Found only in plants
• Prion viral proteins that are able to cause
  diseases by clumping together within cell. 250
  amino acids but no nucleic acid. Scrapie in
  sheep degrades nervous system. Mad Cow disease
  (Bovine spongiform encephalopathy) in cows
  puts holes into brain. In humans, its
  Creutzfeld-Jakob disease.

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A Bacteriophage  

• Host is E. coli

Head
Tail w/ Tail Fibers
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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 Cycle of 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 b y the lytic cycle
are called Virulent
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Lysogenic Cycle

• Infect cell but do not cause disease immediately.
  Instead, they incorporate their nucleic acid into
  hosts for extended periods of time (sometimes
  years).
• May turn lytic or stay incorporated depending on
  conditions.
• Temperate viruses - 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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• HIV that causes AIDS attaches onto cell membrane
  of White Blood Cells, injects RNA, then goes
  through reverse transcriptase to produce DNA.
• This DNA will incorporate itself into host DNA
  for an unknown amount of time.

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So are we going to just sit back and let them
cause diseases in us?

• Prevention
• Antiviral drugs not a lot since viruses arent
  living. Basically change the receptor sites
• Vaccines either inactivated (dead viral
  particles) or attenuated (weakened or altered
  viral particles) are injected into organism.
  Body starts the production of antibodies and
  memory cells to combat viral invaders when needed.

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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