EX 3 Microbial Diversity

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EX 3 Microbial Diversity
2015-04-12 17:20:47
BIOL189 ex3
microbial diversity
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  1. Relative ages of Earth and 1st prokaryotic and eukaryotic fossils
    ~4.6 billion years ago= Earth

    ~3.5 BYA= Prokaryotes appeared

    ~2.1 BYA= Single celled eukaryotes appeared

    ~1.2 BYA= Multicellular eukaryotes appeared
  2. Do prokaryotes or eukaryotes have more total biomass on Earth?
    • Prokaryote biomass is ~10x higher than eukaryotes
    • biomass
  3. Review features of prokaryotic cells
    -smaller than eukaryotes cell

    -lack membrane-enclosed nucleus

    -lack other membrane-enclosed organelles

    -typically have cell walls
  4. Classification of prokaryotes: shapes, associations or attachments, mobility, survival in extreme conditions (endospores), modes of nutrition
    • 1.    
    • Shape:

    • a.    
    • Coccus or cicci-SPHERICAL

    • b.    
    • Bacillus or bacilli- ROD
    • SHAPED

    • c.    
    • Spiral or curved shape

    • 2.    
    • Association or attachment
    • with other cells

    • a.    
    • May form chains or clumps

    • b.    
    • Spiral or curved shape

    • 3.    
    • Mobility

    • a.    
    • Pilli, capsule, flagella,
    • cilia

    • 4.    
    • Survival of extreme
    • conditions

    • a.    
    • Endospore: a thick,
    • protected cell wall which can survive extreme heat and cold, even boiling water

    • 5.    
    • Modes of nutrition-How
    • organisms obtain:

    • a.    
    • Energy:

    • i.     Phototroph-obtains energy from light

    • ii.     Chemotroph-obtains energy from chemical bonds

    • b.    
    • Carbon:

    • i.     Autotroph-obtains carbon from carbon dioxide

    • ii.     Heterotroph-obtains carbon from organic molecules such as
    • gluecose

    • **Multicellular organisms are either
    • Chemoheterotrophs (animals, fungi) or Photoautotrophs (plants, algae)
  5. What is a biofilm and why are they important to people?
    • A special association of one or several species
    • of prokaryotes, and/or protists and fungi which can divide labor and defense
    • against invaders

    •                   -form
    • on rocks, metal and teeth

    •                   -difficult
    • to remove

    •                                     -medical
    • devices, dental plaque, UTI, sinusitis, plants: nitrogen fixation, plants: crop
    • disease, microbial fuel cells, sewage treatment plants
  6. What are the two basic ways that bacteria cause disease?
    Exotixins: proteins secreted into the environment

    Endotoxins: chemical components of the outermembrane of certain bacteria that cause illness
  7. How are archaea related to bacteria and eukarya?
    Archaea has similarities with:

    • -bacteria (small cells, no nucleus, circular
    • genome, no introns)

    • -eukarya
    • (similar DNA replications, histones)
  8. How are archaea classified?
    • There are currently 4 Phyla of Archaea                 
    • -becausethey occupy extreme habitats, they are the most poorly characterized domain
  9. Why are protists placed in the same group? Is this appropriate?
    Protists are Eukaryotes which are not fungi,animals, not plants.  They are notgrouped together because they are closely related, but because they were notwell understood in the past
  10. Where do most protists live?
    • -Oceans, lakes and ponds
    • -damp soil and leaf litter
    • -the bodies of host organisms with which they mayhelp or harm
  11. What are some of the differences among protists?
  12. Be able to recognize the groups of protists by their types and properties: protozoans, slime molds, unicellular and colonial algae, seaweeds
    • Protozoans: protists that live primarily by
    • ingesting food most free-living, but a few parasites

     Slime molds: decomposers- NOT FUNGUS

                      -plasmoidial slime molds: only have one cell, but many nuclei

                      -cellular slime molds: complex life history

    Unicellular and Colonial algae:

    • Algae-photosynthetic
    • portists whose chloroplasts support food chains in aquatic



    -Dinoflagellates: have external plates made of cellulose

    -Diatoms: have glassy cell walls

    -Green algae: unicellular or colonial in fresh water


    Seaweeds: large, multicellular marine algae

    •                   -grouped
    • based on pigments of chloroplasts

                                  -green algae

                                  -red algae

                                 -brown algae-including kelp
  13. Potential exam question: What two processes likely created the membrane-bound organelles in eukaryotic cells? Briefly explain how each works.