Protists




                     Protists
  • Characteristics

  •            A) Organelles

  •            B) Organizati...
• Diversity of plastids produced by
  secondary endosymbiosis                                   Plastid



               ...
Kingdom
Protista is
   very
 diverse.
 15 phyla,
 based on
  the way
they obtain
  energy.




  • Protist habitats are al...
Groups (Phyla)




     7 monophyletic groups




                                                                       F...
Once ingested by a
                                                   host, the trophozoite
                              ...
Parabasalids--Heterotrophic flagellates
                                                      STD
Trichomonas vaginalis


...
Euglenoids


Euglena gracilis




                                                                      Fig. 22-4b, p.354
...
Kinetoplastids

• Kinetoplastids
   – Have a single, large mitochondrion that
     contains an organized mass of DNA calle...
Trypanosomes- transmitted
                                        by the bite of a tsetse fly,
                           ...
Forams & Radiolarians




    Part of marine plankton
                                            Fig. 22-6, p.355




   ...
Radiolarians
• Radiolarians are marine protists….
   – whose tests are fused into one delicate
     piece, which is genera...
Ciliated Alveolates

  cilium




alveolus




                     Ciliates
 • Ciliates, a large varied group of protists...
Paramecium

                                gullet
      food vacuole
      (being emptied)
                              ...
Paramecium




             macronucleus

                            micronucleus



                                    ...
Flagellated Alveolates
• Dinoflagellates




                  Dinoflagellates
• Dinoflagellates
   – Are a diverse group ...
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Protists+Part+1

  1. 1. Protists Protists • Characteristics • A) Organelles • B) Organizational structure Endosymbiotic hypothesis Protists are believe to be the oldest eukaryotes on the evolutionary tree. 1
  2. 2. • Diversity of plastids produced by secondary endosymbiosis Plastid Dinoflagellates Alveolates Apicomplexans Secondary endosymbiosis Cyanobacterium Ciliates Red algae Primary endosymbiosis Stramenopiles Heterotrophic Plastid eukaryote Euglenids Secondary endosymbiosis Green algae Chlorarachniophytes Protists • Groups • Protists, the most nutritionally diverse of all eukaryotes, include – Photoautotrophs, which contain chloroplasts – Heterotrophs, which absorb organic molecules or ingest larger food particles – Mixotrophs, which combine photosynthesis and heterotrophic nutrition 2
  3. 3. Kingdom Protista is very diverse. 15 phyla, based on the way they obtain energy. • Protist habitats are also diverse. • And including freshwater and marine species (a) The freshwater ciliate Stentor, a unicellular protozoan (LM) 100 µm 100 µm (b) Ceratium tripos, a unicellular marine dinoflagellate (LM) 4 cm (c) Delesseria sanguinea, a multicellular marine red alga 500 µm (d) Spirogyra, a filamentous freshwater green alga (inset LM) LE 16-19 Cellular slime molds Choanoflagellates Closest algal relatives of plants Apicomplexans Plasmodial slime molds Animals Dinoflagellates Amoebas Fungi Diplomonads Diatoms Red algae Plants Green algae Euglenozoans Water molds Brown algae Ciliates Alveolates Stramenopila Amoebozoa Ancestral eukaryote 3
  4. 4. Groups (Phyla) 7 monophyletic groups Fig. 22-2, p.352 Parabasalids & Diplomonads • Most primitive • Are adapted to anaerobic environments • Lack plastids • Have mitochondria that lack DNA, an electron transport chain, or citric-acid cycle enzymes Diplomonads • Diplomonads – Have two nuclei and multiple flagella 5 µm (a) Giardia intestinalis, a diplomonad (colorized SEM) 4
  5. 5. Once ingested by a host, the trophozoite emerges to an active state of feeding and motility. It feeds on mucous inside the digestive tract and causes the host to have epigastric pain, excessive gas, and diarrhea with fat and mucous but no blood. This can last from 2 - 4 weeks but for a lactose intolerant individual, it can last up to six months. Diplomonads – 3+1 flagella Giardia lamblia – intestinal parasite Fig. 22-3b,c p.353 Parabasalids • Parabasalids include trichomonads – Which move by means of flagella and an undulating part of the plasma membrane Flagella Undulating membrane 5 µm Trichomonas vaginalis, a parabasalid (colorized SEM) 5
  6. 6. Parabasalids--Heterotrophic flagellates STD Trichomonas vaginalis Fig. 22-3a, p.353 Euglenoids & Kinetoplastids • Single-celled flagellates • Have flagella with a unique internal structure • A diverse clade that includes – Predatory heterotrophs, photosynthetic autotrophs, and pathogenic parasites • The main feature that distinguishes protists in this clade – Is the presence of a spiral or crystalline rod of unknown function inside their flagella Flagella 0.2 µm Crystalline rod Ring of microtubules 6
  7. 7. Euglenoids Euglena gracilis Fig. 22-4b, p.354 Euglenoids Euglena gracilis long flagellum nucleus chloroplast mitochondrion Fig. 22-4a2, p.354 Diversity of Kingdom Protista Phylum Euglenophyta Freshwater Propels the body through This phylum is a water. typical example of the difficulties in categorizing protists: 1/3 have chloroplasts, the other 2/3 do not. For photosynthesis No sexual reproduction. Longitudinal fission. 7
  8. 8. Kinetoplastids • Kinetoplastids – Have a single, large mitochondrion that contains an organized mass of DNA called a kinetoplast – Include free-living consumers of bacteria in freshwater, marine, and moist terrestrial ecosystems – Known best for its parasitic representatives Kinetoplastids -- Heterotrophs (parasites) single, long mitochondrion Golgi body long flagellum attached to undulating membrane nucleus vacuole ER Fig. 22-5a, p.355 Trypanosoma brucei --- sleeping sickness undulating membrane attached to flagellum red blood cell Fig. 22-5b, p.355 8
  9. 9. Trypanosomes- transmitted by the bite of a tsetse fly, cause African Sleeping Sickness. 9 µm Trypanosoma transferred by Triatomine bugs (kissing bugs) causes South American Chagas disease Forams & Radiolarians 9
  10. 10. Forams & Radiolarians Part of marine plankton Fig. 22-6, p.355 Foraminiferans (Forams) • Foraminiferans, or forams – Are named for their porous, generally multichambered shells, called tests 20 µm Foraminiferans (Forams) • Pseudopodia extend through the pores in the test • Foram tests in marine sediments – Form an extensive fossil record 10
  11. 11. Radiolarians • Radiolarians are marine protists…. – whose tests are fused into one delicate piece, which is generally made of silica – that phagocytose microorganisms with their pseudopodia • The pseudopodia of radiolarians, known as axopodia – Radiate from the central body Axopodia 200 µm Alveolates Alveoli 0.2 µm Cillium/flagellum 11
  12. 12. Ciliated Alveolates cilium alveolus Ciliates • Ciliates, a large varied group of protists – Are named for their use of cilia to move and feed – Have large macronuclei and small micronuclei Paramecium Paramecium Didinium 12
  13. 13. Paramecium gullet food vacuole (being emptied) trichocysts cilia contractile vacuole emptied filled contractile macronucleus vacuole micronucleus Fig. 22-7c, p.356 intact trichocyst Paramecium contractile vacuole pellicle Fig. 22-7a2, p.356 13
  14. 14. Paramecium macronucleus micronucleus Fig. 22-7c, p.356 Fig. 22-8, p.357 Fig. 22-8n, p.357 14
  15. 15. Flagellated Alveolates • Dinoflagellates Dinoflagellates • Dinoflagellates – Are a diverse group of aquatic photoautotrophs and heterotrophs – Are abundant components of both marine and freshwater phytoplankton Flagellated Alveolates • Dinoflagellates Some are bioluminescent Some produce toxins 15

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