Eukaryotic Diversity

Diplomonads

• Unicellular, flagellated protists
• Lack mitochondria and chloroplasts
• Live in anoxic habitats
  • Animal intestines
• Conserve energy from fermentation
• Can cause diseases in:
  • Fish
  • Domestic animals
  • Humans
• Contain two nuclei of equal size
• Contain mitosomes
• Reduced mitochondria lacking electron transport proteins
• Genome quite compact
  • Contains few introns in genome
• Lacks genes for metabolic pathways such as the citric acid cycle

Euglenozoans

• Unicellular
• Can be free-living or parasitic flagellated
  • Kinetoplastids and euglenids
• Kinetoplastids
  • Kinteoplast
    • Mass of DNA present in single, large mitochondrion
  • Primarily live in aquatic habitats
  • Some are parasites of animals and humans
  • Responsible for Trypanosoma cells
    • Trypanosoma brucei causes African sleeping sickness, which is a chronic and fatal disease
    • Trypanosoma cruzi causes Chagas disease
      • Spreads by a “kissing bug”
      • Can be fatal
    • Leishmania causes cutaneous and systemic leishmaniasis
  • Euglenids
    • Motile and nonpatbhogenic
    • Chemotrophic and phototrophic
    • Contain two flagella
      • Dorsal and Ventral
    • Live in aquatic habitats
      • Freshwater and Marine
    • Contain chloroplasts
    • In darkness they can lose chloroplasts and live as cheoorganotrophs
    • Many feed on cells by phagocytosis

Alveolates

• Contain aveoli
  • Cytoplasmic sacs located under the cytoplasmic membrane
  • Helps cell maintain osmotic balance by controlling water influx and efflux
  • Some function as armor plates
• Ciliates
  • Contain cilia
    • Function in motility and some cover the cell
    • Paramecium are widely distributed species
  • Have macronuclei and micronuclei
  • Maconucleus
    • Growth and feeding
  • Micronucleus
    • Sexual reproduction
  • Parramecium
    • Hosts for endosybiotic prokaryotes and eukaryotes
  • Obligate anaerobe ciliates
    • Present in rumen of animals
    • Some can be parasites to animals
      • Balatidium coli is an intestinal parasite in animals
    • Dinoflagellates
      • Marine and freshwater phototrophic alveolates
      • Have two flagella of differents lengths and with different points of insertion
        • Transverse and longitudinal insertion points
      • Some are free-living and some share symbiotic relationships with coral reefs
      • Some are toxic
        • Gonyaulax cells or red tides
          • Kills fish and poisons humans
        • Pfiesteria
          • Infect and kill fish due to neurotoxins that affect movement and destroy skin
        • Apicomplexans
          • Nonphototrophic obligate parasites
          • Can cuase malaria, toxoplasmosis, and coccidiosis
          • Nonmotile adult stages
          • Produce sporozoites
            • Function in transmission of the parasite to a new host
          • Apicoplasts
            • Dengenerate chloroplasts that lack pigments and phototophic capacity
            • Catalyze fatty acid, isoprenoidm and heme biosynthesis and export products to cytoplasm

Stramenophiles

• Contain chemoorganotrophic and phototrophic microorganisms and macroorganisms
• Possess flagella
  • Diatoms
    • Unicellular
    • Phototrophic
    • Major component of plankton
    • Produce cell wall made of silica
      • Protects cell against predation
    • Diatom Frustule
      • Resistant to decay
    • Oomycetes
      • Water molds
        • Contain flagellated cells
      • Coenocytic hyphae
      • Cell walls are made of cellulose
      • Phytophthora infestans
        • Causes blight disease of potatoes
      • Pythium
        • Causes white rust of agricultural crops
      • Golden algae
        • Chrysophytes
        • Primarily unicellular marine and freshwater phototrophs
        • Two flagella
        • Chlorophyll c major pigment
      • Brown algae
        • Marine and multicellular
        • Typically macroscopic
        • No unicellular brown algae
        • Seaweeds are considered brown algae

Cercozoans

• Chlorarachniophytes
  • Freshwater and marine amoeba-like phototrophs
  • Develop a flagellum for dispersal
  • Acquisition of green algal chloroplasts is a prime example of secondary endosymbiosis
• Foraminifera
  • Exclusively marine and form shell-like structures called tests
    • Tests are organic materials reinforced with calcium carbonate
  • Hosts a variety of algae that form endosymbiotic relationships with the protists
  • Tests are resistant to decay and readily fossilized

Radiolarians

• Mostly planktonic marine eukaryotes
• Form threadlike pseudopodia
• Strictly heterotrophic
• Reside in the upper 100m or so of ocean waters
• Consume bacteria and particulate organic matter
• Some associate with algae that take on a symbiotic role and supply nutrients to the radiolarian
• Tests have radial symmetry

Amoebozoa

• Terrestrial and aquatic protists
• Lobe-shaped pseudopodia for movement and feeding
• Gymnamoebas
  • Free-living protists
  • Live in aquatic and soil environments
  • Amoeboid movement
    • Facilitates pseudopodia movement
  • Amoeba
    • Common organism in pond waters
  • Entamoebas
    • Parasites of vertebrates and invertebrates
    • Live in oral or intestinal tract of humans
    • Entamoeba histolytica
      • Pathogenic to humans and cause amebic dysentery
      • Forms cyst
    • Slime molds
      • Motile
      • Plasmodial slime molds
        • Vegetative form are masses of protoplasm
      • Cellular slime molds
        • Vegetative form are single amoebae
      • Live primarily on decaying plant matter
      • Form differentiated spore-like structures that can remain dormant and then germinate

Chytridiomycetes

• Earliest diverging lineage of fungi
• Fruiting body contains sexual spores
  • Flagellated and motile
• Some exists as single cells whereas others form colonies with hyphae
• Batrachochytrium dendrobatidis
  • Causes chytridiomycosis of frogs
• Some are obligate anaerobes
• Inhabit rumen of ruminant animals
• Neocallimasitx
  • Inhabits the rumen and conserves energy from the fermentation of sugars to acids

Zygomycetes

• Known for food spoilage
• Found in soil and on decaying plant material
• Rhizopus
  • Black bread mold
  • Undergoes asexual and sexual reproduction

Glomeromycetes

• Important in mycorrhizal associations
• Form symbiotic relationship with plant roots
• Relatively small
• Obligately symbiotic and all species form relations with endomycorrhizae
• Played pivotal role in early vascular plants ability to colonize on land
• Reproduce asexually and are coencytic

Ascomycetes

• Single-celled species
  • Saccharomyces (Baker’s yeast)
• Common mold
  • Aspergillus
• Found in aquatic and terrestrial environments
• Reproduce asexually by production of conidia that form at tips of specialized hyphae
• Saccharomyces
  • Reproduce sexually in which two cells fuse, zygote

Basidiomycetes

• Basidium
  • Structure in which haploid basidiospores are formed by meiosis
  • Basidiocarp
    • Mushroom fruiting body
    • Starts out as mycelium that differentiates into a small button-shaped structure underground that then expands into the full-grown basidiocarp
  • Diakaryotic basdia
    • Borne on the underside of the basdiocarp on flat plates called gills, which are attached to the cap of the mushroom

Algae

• Red Algae
  • Rhodophytes
  • Inhabit marine environment
  • Few species found in freshwater and terrestrial habitat
  • Phototrophic and contain chlorophyll a
  • Chloroplasts contain phycobiliproteins
    • Major light harvesting pigments of cyanobacteria
  • Red color results from phycoerythrin
  • Most species are multicellular
  • Lack flagella
  • Some are filamentous, leafy, or coralline in structure
  • Unicellular
    • Cyaniadiales
      • Live in acidic hot springs at temperatures and at pH values 0.5 to 4.0
    • Green Algae
      • Chlorophytes
      • Conatain chlorophylls a and b
      • Lack phycobiliproteins
      • Chlorophytes and charophyceans
      • Chlorophytes
        • Unicellular and multicellular species
        • Volvox(colonial level)
          • Forms colonies composed of several hundred flagellated cells
            • Some are motile and carry out photosynthesis
            • Some specialize in reproduction
          • Cells are interconnected by thin strands of cytoplasm that allow the entire colony to swim in a coordinated fashion
        • Some green algae have potential for biofuels
        • Endolithic
          • Some grow inside of rocks
            • Cold and dry environments