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Prokaryotes and Protists

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					Prokaryotes and Protists

        Chapter 16
 Organizing Life
• Domains
   – What are they?
• Linnaean hierarchy
   – Arrangement of taxons
   – http://animaldiversity.ummz.umich.edu/site/index.html
• Tree of Life
   – Branched organization
   – http://www.tolweb.org/tree/
• Cell Types
   – Prokaryotes or eukaryotes
           Comparing Cell Types
Prokaryotes                     Eukaryotes
• 1-5 um in size                • 10-100 um in size
• 10X’s more biomass            • 10X’s larger in size
• Wider range of environments   • Membrane bound nucleus
• Greater diversity               and organelles
• Single, circular chromosome   • DNA arranged on multiple
• Can live without eukaryotes     chromosomes
                                • Can’t live without prokaryotes
                  Prokaryotic Shapes
 Cocci
    Sperical
    Chains or clusters
    E.g streptococci and staphylococci
     (MRSA and beta-lactams)
 Bacilli
    Rod shaped
    Occur singularly, in pairs, or chains
    E.g. soil organisms
 Spirochetes
    Corkscrew shaped
    E.g. Borrelia burgdorferi (Lyme
     disease)
           Prokaryote Characteristics
 Cell wall
    Maintains shape, provides protection, and prevents lysis
          Salt and curing meats
    Gram stains identifed as gram (+) or gram (-)
           (+) simple walls with thicker peptidoglycan (sugar polymer)
           (-) more complex walls with less peptidoglycan
           More resistant to antibiotics
 Capsule
    Sticky polysaccharides or proteins to adhere to substrates
    Prevent immune system attacks
 Pili
    Hair-like appendages for adhesion
    Specialized for DNA transfer
        Prokaryotic Characteristics

 Motility
    Many utilize a flagella
 Reproduction
    Review division by binary fission
     Occurs quickly (E. coli overnight from 1 to 16 million)
 Adaptation
   Form resistant structures like endospores during inhospitable times
      Bacillus anthracis (anthrax) and Clostridium botulinum (botulism)
 Internal Organization
    All DNA is actively used
      Lack junk DNA found in eukaryotes called __________?
    Small genetic rings that aid in resistance called plasmids
    Smaller ribosomal = efficiency of antibiotics
         Prokaryotic Nourishment
• Unmatched diversity in nutrient attainment
• Nutrients provide energy and carbon
• Naming
   – Photo- or chemo- = energy source
   – Auto- or hetero- = carbon source
   – -troph = to eat
                          Biofilms
• Surface coating colonies of prokaryotes
   – Signal to recruit more cells and produce sticky proteins
   – E.g. dental plaque, UTI’s, or sewer treatment
• Can be 1+ species
• Channels provide nutrients to entire colony
                      Prokaryotes
• Archaea
  – Live where other organisms can’t survive,
    ‘extremophiles’
     • Thermophiles
        – Very hot water such as geysers and hot springs
     • Halophiles
        – Salt environments such as the Great Salt Lake and salt farms
     • Methanogens
        – Animal guts and swamps where they produce methane gas
• Bacteria
  – Few species are pathogens, disease-causing organisms
  – Most not harmful to humans
             9 Bacterial Clades
• Proteobacteria (5 subgroups)
    – Gram negative
•   Gram positive
•   Chlamydias
•   Spirochetes
•   Cyanobacteria
                     Proteobacteria
 Alpha (α)
   Rhizobium  root nodules, fix N2
   Foreign DNA carriers into crop plant genomes
 Gamma (γ)
   Photosynthetic examples
   Animal intestine inhabitants                                 Salmonella
       E.g Salmonella, Vibrio cholerae, and Escheria coli
 Delta (δ)                                                        Myxobacteria

   Slime secreting myxobacteria
      Can form fruiting bodies for selves when food is scarce
   Bdellovibrio attacks other bacteria
                       Gram Positive
 Actinomycetes
    Branched chains of cells or are solitary
    Pathogenic or free-living
       Mycobacteria leprae and mycobacteria tuberculosis
       Live in soil and give it the ‘earthy’ smell
 Streptomyces
    Cultured by pharmaceutical companies as antibiotics
 Bacillus anthracis
    Form endospores, a cell within a cell that dehydrates and lies dormant
     till more favorable conditions exist                       Bacillus anthracis
 Staphylococcus and streptococcus
 Mycoplasmas
    Lack cell walls
    Tiniest of all known cells
     Other Bacterial Clades
 Chlamydias
                                                     Chlamydia
   Obligate intracellular parasite
   Common cause of blindness (developing countries;
    conjunctivitis) and most common STD (United
    States)
 Spirochetes
   Spiral through environments by rotating internal
    filaments
   E.g Treponema pallidum (syphilis) and Borrelia
    burgdorferi (Lyme disease)
 Cyanobacteria
   Only Only prokaryote
   Food for freshwater and marine ecosystems
                 Bacterial Poisons

 Exotoxins are proteins secreted by bacteria
    Clostridium tetani produces muscle spasms (lockjaw)
    Staphylococcus aureus common on skin and in nasal passages
      Produces multiple types
      TSS, septicemia, and pneumonia
   Can be acquired from genetic transfer between species
       E. coli Acquires genes that produce harmful effects
 Endotoxins are components of gram (-) outer membranes
   Released when cell dies or digested by defensive cell
   All cause same general symptoms (fever, aches, and blood
    pressure drops)
       Neisseria meningitidis (bacterial meningitis) and Salmonella (typhoid
        fever and salmonellosis)
Bacteria, Human Populations, & Disease
• Improvements in sanitation
  – Water treatment and sewer systems
• Antibiotic development
  – Increase in bacterial resistance
• Education
  – Importance of seeking treatment
  – Prevention
• Biological weapons
• Bioremediation
                  Protists
• Single or multicellular eukaryotes
• Source of food and parasites
• Autotrophic (algae) or heterotrophic
  (protozoan)
• Found in/near water (most) or in animal host
   Protist Clades
• Regularly changing
  hypotheses
• Divergence not truly
  simultaneous
• Eukaryotic origin is
  unknown
            Diplomonads and Parabasalids
• Heterotrophs with altered mitochondria
• Diplomonads
   –   Possibly most ancient Protist lineage
   –   Mitochondria lack DNA & ETC
   –   Anaerobic
   –   E.g Giardia intestinalis ‘backpackers disease”
• Parabasalids
   – Anaerobic energy generation
   – E.g Trichomonas vaginalis (Trichomoniasis)
        • Lives in the vagina
             – pH shift to basic = growth
             – Feed on WBC and bacteria
        • Males rarely symptomatic b/c food availability
          limits population size
        • Treatment is available, but resistance is increasing
                  Euglenozoans
• Flagella have a crystalline rod structure
• Heterotrophs, photoautotrophs, &
  pathogenic parasites
• E.g Trypanosoma
   – Causes sleeping sickness
   – Spread by African tsetse fly
   – Avoid detection by changing protein structure
• E.g Euglena
   – Common in pond water
   – Reproduce by binary fission
   – Simultaneously heterotrophic and autotrophic
                     Alveolates
• Contain alveoli, membranous sacs below
  the PM
• Dinoflagellates
   – Red tide blooms
   – Toxins kill fish and can affect humans
• Ciliates
   – Cilia to move and feed
   – 2 types of nuclei, 1 for daily activities (single,
     large) and 1 (many, small) for reproduction
      • E.g Paramecium or Stentor
• Apicomplexans
   – Animal parasites
      • E.g Plasmodium (malaria)
          Stramenopiles
• Have hairy and smooth flagella
• Water molds
   – Decomposers in moist environments
   – May be parasitic (Ireland potato famine)
• Diatoms
   – Cell wall of silica
   – Fresh and marine organism food source
   – Diatomaceous earth
• Brown algae
   – Autotrophic
   – Kelp
                     Amoebozoans
• Use pseudopodia for movement and feeding
• Free-living amoebas
• Parasitic types
  – E.g. amoebic dysentery
• Slime molds
  – Organisms found in moist, decaying matter
  – Spread under favorable conditions, form spore
    producing structures under less favorable ones
     • Plasmodial slime molds are brightly colored
         – Single-celled plasmodium
         – Cell cycle research
     • Cellular slime molds solitary until food is scarce
         – Cell differentiation research
   Foraminiferans and Radiolarians
• Move and feed by thread like
  psuedopodia
• Forams
  – Marine and fresh water organisms
  – Pseudopodia extend through tests of
    calcium carbonate
• Radiolarians
  – Marine
  – Internal silica shell and organic outer test
              Land Plant Relatives
• Red algae
  – Carrageenan stabilizes yogurt,
    chocolate milk, and pudding
  – Nori in sushi
  – Agar for medium plates
• Green algae
  – Volvox, colonial hollow balls
    composed of 100’s of
    biflagellated cells

				
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posted:2/10/2012
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