lecture 6c

• Protists


  Eukaryotic

  mostly heterotrophs

  unicellular, colonial, multicellular

  mostly motile

  free living in aquatic (marine, freshwater) and terrestrial
• Protists


  makes majority of the plankton
• Polyphyletic


  Protists used to described diverse group of microscopic eukaryotic organisms and is not a formal taxonomic term because organisms does not share evolutionary origin. They also do not share the same common ancestor which means it is ________
• Endocytosis


  general term describing a process by which cells absorb external material by engulfing it with cell membrane
• Vesicle


  Endocytosis occurs when a portion of the cell cytoplasm moves forward and surrounds the particle that has come in contact with the cell membrane. The movement of the cytoplasm continues until the particle is completely engulfed in a pocket called
• Lysosome

  Fuses with the vesicle and is responsible for the digestion of the particle.

  
  

  Are membranous organelles

  composed of digestive, hydrolytic enzymes which include maltases, sucrases, lipases, and nucleases. These enzymes are

  involved in digesting the macromolecules.
• phagocytosis


  engulfing and digesting of microscopically visible particles (amoeba and other protozoan)
• pinocytosis


  engulfing and digesting dissolved particles "cell drinking"
• Trophozoite


  Is the vegetative form, non-infectious, metabolically active invasive stage and form that inhabits the gut of its host
• Cyst


  Dormant yet infectious form and functions to protect against adverse conditions, site for nuclear reorganization and cell division, and means of transfer between hosy
• entamoeba


  forms cysts that are transmitted from person to person by fecal contamination of water, food, and eating utensils.

  During the encystment process, the protozoan cell undergoes a series of changes that considerably reduce the complexity of the organism.
• Pellicle


  bands of protein inside the membrane that

  adds rigidity to the cell of a euglena
• Phototaxis


  locomotory movement that occurs when a whole organism moves towards or away from stimulus of light. This is advantageous for phototrophic organisms as they can orient themselves most efficiently to receive light for photosynthesis.
• Stigma


  for phototaxis of a euglena
• chloroplast


  for photosynthesis of a euglena
• Ectoplasm


  ·Semisolid/ gelatinous cytoplasm that imparts rigidity to cell

  
  

  · Outer, non-granulated layer of cytoplasm

  
  

  · Typically watery and immediately adjacent to the cytoplasm
• Endoplasm


  · Area inside ectoplasm that contains most of the organelles

  
  

  · Inner, often granulated denser part of cytoplasm
• Macronucleus


  regulates somatic functions

  (locomotion, osmoregulation,

  cell regeneration, feeding) by

  directing protein synthesis
• micronucleus


  functions in sexual reproduction,

  regeneration of macronucleus
• food vacuole


  - sites of food digestion

  - fuses with lysosomes
• contractile vacuole


  - for excretion, osmo-regulation and water balance (example is paramecium which has 2 of these_
• pseudopodia


  "false feet" are blunt lobe-like extensions of the cytoplasm
• flagella


  thin, long whip-like projections

  arising from the surface of the cell
• cilia


  similar to but shorter and more

  numerous than flagella
• Carbon carbonate and silica


  shells of protists are made of?
• Foraminiferans


  calcium-carbonate shelled protists
• diatoms and radiolarians


  silica shelled protists
• Holozoic


  Food-taking type that employs phagocytosis (e.g., Entamoeba histolytica and Balantidium coli)
• saprozoic


  Food-taking type when nutrients cross plasma membrane by pinocytosis, diffusion, carrier-mediated transport or osmosis by the process of osmotrophy (e.g., chilomonas, polytoma, and some species of euglena)
• Syngamy and conjugation


  Sexual reproduction processes of protists
• conjugation


  exchange of nuclei between two organisms
• Schizony


  multiple fission where nucleus of the cell

  divides multiple times before the rest of the cell

  divides
• Fission, budding, schizony


  Asexual reproduction processes of protists
• Excavata


  Key Genera: Giardia, Trichomonas, Trypanosoma, Euglena
• parabasalids, euglenids, kinetoplastids, diplomonads


  groups of excavata
• Excavata


  Super group of protists that

  
  

  • includes both chemoorganotrophs and phototrophs

  
  

  • some species anaerobic motile via flagella

  
  

  • Habitat - anoxic habitats (such as animal intestines),

  freshwater

  
  

  • some free-living; others may live as either symbionts or

  as parasites
• Diplomonads


  -serious common diseases in fish, domestic animals, and humans

  
  

  - contain two nuclei of equal size, each

  with 4 associated flagella

  
  

  - with mitosomes (modified

  mitochondria)

  
  

  - some free-living, most are commensal

  
  

  - can be parasitic and anaerobic
• Parabasalids


  - contain parabasal body (for

  structural support), lacks mitochondria

  - with hydrogenosome

  - anaerobic

  - binary fission

  - live in intestinal and urogenital tract

  of vertebrates and invertebrates as

  parasites or commensal symbionts
• Hydrogenosome


  site for

  pyruvate metabolism of a parabasalids
• Kinetoplastids


  - From subgroup excavata that contain kinetoplast

  - with single flagellum

  - free-living found in soil or

  aquatic environment

  - primarily feed on bacteria,

  some parasites of humans

  and vertebrate animals