Bacteria, Viruses, Prions, and Protists

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Bacteria, Viruses, Prions, and Protists
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Bacteria

• Unicellular or Multicellular?
• Prokaryotic or Eukaryotic?
• Cells Walls?

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Bacteria

• Unicellular
• Prokaryotes
• Cells walls containing peptidoglycan

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Bacteria

• Extremely Abundant
• Cover nearly every square centimeter of Earth

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What are the differences between eubacteria and
archaebacteria?
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Eubacteria versus Archaebacteria

• Cell walls of Eubacteria have peptidoglycans
  while those of Archaebacteria do not.
• DNA sequences of archaebacteria is more similar
  to that of eukaryotes than to the DNA of
  eubacteria
• Archaebacteria often live in very extreme
  environments (hot springs, digestive tracts,
  Great Salt Lake, etc.)

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Bacterial Shapes

• Bacilli rod shaped
• Cocci spherical
• Spirilla spiral, corkscrew

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Grouping of Bacteria

• Diplo- Groups of two
• Strepto- chains
• Staphylo- Grapelike clusters

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Diplococcus
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Streptococcus Causes Strep Throat
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Staphylococcus
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Bacillus - E. coli
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Cell Walls

• Gram positive stain violet due to thick
  peptidoglycan walls
• Gram negative stain pink/red, have much thinner
  walls inside lipid layer

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Metabolism

• Heterotrophs
• Chemoheterotrophs must take in organic molecules
  and a supply of carbon
• Photoheterotrophs are photosynthetic but also
  need to take in organic molecules for carbon
  source

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Metabolism

• Photoautotrophs use light energy to make carbon
  compounds
• Chemoautotrophs use energy from chemical
  reactions to make carbon compounds
• Where might each type of bacteria be found?

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Binary Fission

• When a bacteria grows so that it has doubled in
  size, it replicates its DNA and divides in half
• Is this sexual or asexual?
• Identical or different daughter cells?

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Conjugation

• Some bacteria are able to exchange genetic
  information
• A hollow bridge forms between two bacteria and
  genes move from one cell to the other
• Increases genetic diversity of a population

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Pili

• Short protein appendages
• Smaller than flagella
• Adhere bacteria to surfaces
• Used in conjugation for Exchange of genetic
  information
• Aid Flotation by increasing buoyancy

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Pili in Conjugation
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Conjugation
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Spore Formation

• Spores are formed when the bacteria produces a
  thick internal wall that encloses the DNA and
  part of the cytoplasm
• Why do you think this would be beneficial for
  bacteria?

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Spore Formation

• Occurs when conditions are unfavorable for growth
• Can remain dormant for years until conditions
  improve

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Spore Formation
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What are some benefits of bacteria?
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Benefits of Bacteria

• Some are producers that undergo photosynthesis
• Some are decomposers that break down dead matter
  to recycle the nutrients
• Some convert nitrogen gas to a form that can be
  used by plants (nitrogen fixation)

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What are some dangers of bacteria?
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Dangers of Bacteria

• Break down cells and tissues for food
• Example Tuberculosis (destroys lung tissue)
• Release toxins (poisons) that travel through the
  body
• Example Streptococcus releases toxins into the
  blood stream causes strep throat and scarlet fever

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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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Vaccines

• A vaccine is a preparation of weakened or killed
  pathogens that are injected into the body
• This stimulates the body to produce immunity to
  the disease

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Vaccines

• Why do you think we dont vaccinate everyone for
  all disease we have created vaccines for?

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Antibiotics

• Antibiotics block the growth and reproduction of
  bacteria
• Used to treat bacterial infections

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Solve the Problem

• What would you do to find out what causes the
  tobacco leaves to be diseased?

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Viruses

• A virus is a core of DNA or RNA surrounded by a
  protein coat (capsid)

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Viruses

• They can only reproduce by infecting living cells
• They enter a cell and use its cell machinery to
  produce more viruses

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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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Retroviruses

• Contain RNA as genetic information instead of DNA

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Are Viruses Living?

• Cannot reproduce alone, must have a host cell
• Do not undergo growth or development
• Do not obtain or use energy
• Evolve

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Figure 19-11 Viruses and Cells
Section 19-2
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Prions

• Diseases such as Scrapie (in sheep) and Mad Cow
  Disease are not caused by bacteria or viruses.
  What could cause them?

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Prions

• Contain only protein
• Cause disease by forming protein clumps which
  then induce normal proteins to become Prions
• The build up eventually damages nerve tissue

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Protists

• Domain?
• Kingdom?
• Prokaryotic or Eukaryotic?

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Protists

• Domain Eukarya
• Kingdom Protists
• Eukaryotic

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Protists

• Protists are defined by what they are not.
• Protists are eukaryotes that are not animals,
  plants, or fungi.
• They were the first eukaryotic organisms on earth.

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Types of Protists

• Animal-Like Protists heterotrophs
• Plant-Like Protists produce food through
  photosynthesis
• Fungus-Like Protists obtain food by external
  digestion

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Animal-Like Protists

• Heterotrophs

cilliate
sporozoan
Sarcodine (amoeba)
zooflagellate
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Animal-Like Protists

• Malaria
• African Sleeping Sickness

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Plant-Like Protists

• Carry out photosynthesis

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Fungus-Like Protists

• Grow in damp, nutrient rich environments
• Absorb food through cell membranes