EUKARYOTES

• Eukaryotes


  Organisms whose cells have a nucleus enclosed within membranes
• Kingdom Fungi


  • Aerobic or facultatively anaerobic chemoheterotrophs with chitin cell walls
  • Includes unicellular yeasts and multicellular molds & mushrooms
  • Mostly are decomposers, while only a few are parasites of plants & animals

  
• Fungal dimorphism


  Ability to exist as both yeasts (nonfilamentous unicellular spherical or oval fungi) and molds or fleshy fungi (filamentous multicellular)

  
• Fungal morphology


  • Thallus (body)
  • Mycelium
  • Hyphae (vegetative and reproductive)
  • Spores

  
• Fungal adaptations


  • Fungal growth is better in an environment with pH of 5.0
  • Almost all molds are aerobic, most yeasts are facultatively anaerobic
  • Most are more resistant to osmotic pressure & moisture depletion
• Economic effects of fungi


  • Some fungi are used in production of food
  • Some fungi are used for biological control of pests
  • Fungi more commonly cause spoilage of fruits & vegetables than do bacteria
  • Many fungi cause disease in plants
• Kingdom Plantae: Algae


  • Unicellular filamentous or multicellular photoautotrophs with cellulose cell walls
  • Some algae produce oxygen
  • Lack the usual tissues of plants (no roots, stems or leaves)
  • Can reproduce asexually by cell division & fragmentation, or sexually

  
• Algae phyla


  • Brown algae
  • Red algae
  • Green algae
  • Diatoms
  • Dinoflagellates (plankton)
  • Oomycotes (water molds)

  
• Algae


  • Plankton (dinoflagellates)
  • Euglena

  
• Roles of algae in nature


  • Primary producers in aquatic food chains
  • Planktonic algae produce the most oxygen in the Earth's atmosphere
  • Some species can act as symbionts in animals
• Kingdom Protista: Protozoa


  • Unicellular mostly-aerobic chemoheterotrophs with a pellicle, a cystostome (mouth) & an anal pore
  • Usually found in soil & water and as normal microbiota in animals
  • Can reproduce sexually by conjugation, or asexually by fission/budding/schizogony
• Protozoa


  • Amoeba
  • Giardia
  • Paramecium
• Protozoan life cycle


  Cyst --> Trophozoite
• Protozoan life cycle


  • Entamoeba
• Protozoan


  • Plasmodium (merozoites & schizonts)

  
• Kingdom Animalia: Helminths


  • Multicellular chemoheterotrophs which are oftentimes parasitic to humans
  • Includes the flatworms (platyhelminths) & the roundworms (nematodes)
  • Life cycle is modified for parasitism (larval stages require an intermediate host, adult stages are found in their definitive host)

  
• Platyhelminths (flatworms)


  • Flattened dorsoventrally
  • Includes the flukes & cestodes (tapeworms)
  • Some (parasitic) lack a digestive system but may have an oral sucker for attachment
  • Microscopic forms range from eggs (cestodes) to adults (flukes)
• Platyhelminths


  • Flukes (Chlonorchis)
  • Schistosoma (cercaria & ova)

  
• Nematodes (roundworms)


  • Non-flattened with complete digestive system
  • Includes the parasitic worms such as Ascaris
  • Infective stages differ per species: either eggs or larvae
• Lab exercise 6: slide viewing