Protists

• Invertebrates


  Organisms without a backbone
• Basis for classification of organisms

  • Advancement in body structure organisation
  • Habitat
  • Lifestyle
  • Biochemical and molecular characteristics
• Kingdoms of life (in some widely used taxonomic systems)

  • Monera (prokaryotae)
  • Protista
  • Fungi
  • Plantae
  • Animalia
• Eukarya (eukaryotes)


  Composed of one or more cells containing visible evidence of nuclei and organelles
• Kingdoms of Eukarya important for this course

  • Protista
  • Animalia
• Protista


  Kingdom comprising a variety of unicellular, coenocytic, colonial and multicellular eukaryotic organisms
• Protists


  Eukaryotic microorganisms and their immediate descendants, defined by exclusion (not animals, plants, fungi, or prokaryotes)
• Types of Protists

  • Animal-like
  • Plant-like
  • Fungi-like
• For this course we shall restrict ourselves to protists that are animal-like
• Protozoa are usually the protists that are animal-like
• The plant-like protists are algae
• Animal-like Protists: The Protozoans ("first animals")


  • Single-celled (unicellular) organisms
  • Some may gather to form colonies but do not depend on one other for most of their life processes
  • Some colonies can have specialization among members
• Ectoplasm


  The outer and relatively clear and firm part of the cytoplasm
• Endoplasm


  The more fluid and granular inner part of the cytoplasm
• Animal-like protists lack a cell wall
• Animal-like Protists


  • Microscopic, ranging from 0.01-0.5mm in diameter
  • Most are naked, but some have a simple endoskeleton or exoskeleton
  • All forms of body symmetries are present
  • No organs or tissues are present but possess highly specialized cell organelles
• Vesicles


  Membrane-enclosed compartments that increase the effective surface area of large unicellular protists
• Isotonic


  Having a solute concentration similar to the environment
• Hypertonic


  Having a higher concentration of solutes than the environment
• Contractile vacuoles

  Organelles that collect and expel excess water in freshwater protists
• Food vacuoles


  Organelles that engulf and digest food through endocytosis
• Types of nutrition in animal-like protists

  • Autotrophic
  • Heterotrophic
• Parasitic


  Obtaining nutrients from a host organism
• Saprozoic


  Obtaining nutrients from dead or decaying organic matter
• Types of endocytosis


  • Phagocytosis (cell-eating)
  • Pinocytosis (cell-drinking)
  • Receptor-mediated endocytosis
• Amoeboid motion


  • Forming pseudopods (extensions of the constantly changing body mass) that the cell flows into
• Types of movement in animal-like protists

  • Amoeboid motion
  • Ciliary action
  • Flagellar locomotion
• Cilia

  Tiny, hairlike organelles that beat in a coordinated fashion to move the cell
• Flagella


  Whip-like organelles that move to push or pull the cell forward
• Symbiosis


  Persistent biological interactions where organisms of different species live together, either for mutual benefit (mutualism), where one benefits with little effect on the other (commensalism), or where one benefits at the expense of the other (parasitism)
• Forms of asexual reproduction in protists

  • Binary fission
  • Multiple fission or schizogony
  • Budding
• Binary fission


  Simple splitting of a parent cell into two daughter cells, with division of nucleus (mitosis) followed by division of the cytoplasm (cytokinesis)
• Multiple fission or schizogony


  Splitting of a parent cell into more than two daughter cells
• Budding


  Outgrowth of a new cell from the surface of an old one
• Sub-phyla of Phylum Sarcomastigophora

  • Sarcodina
  • Mastigophora
• Sarcodina


  • Largest sub-phylum, comprising free-living naked amoebae and amoebae with shells or tests
• Shelled amoebae


  • Arcella
  • Difflugia
• Mastigophora


  • Includes parasitic species that cause diseases in animals
• Symbiotic member of Mastigophora


  • Trichonympha
• Other phyla of animal-like protists

  • Apicomplexa
  • Ciliophora
  • Labyrinthomorpha
  • Microspora
  • Acetospora
  • Myxozoa