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Protists

Protists. Chapter 29. Protists. Protists are the most diverse of the four eukaryotic kingdoms -Unicellular, colonial and multicellular groups The kingdom Protista is paraphyletic and grouped for convenience The 15 major protist phyla are grouped into seven major monophyletic groups.

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Protists

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  1. Protists Chapter 29

  2. Protists Protists are the most diverse of the four eukaryotic kingdoms -Unicellular, colonial and multicellular groups The kingdom Protista is paraphyletic and grouped for convenience The 15 major protist phyla are grouped into seven major monophyletic groups

  3. Protists

  4. Protists (Cont.)

  5. Eukaryotic Origins The nucleus and endoplasmic reticulum arose from infoldings of prokaryotic cell membrane

  6. General Biology of the Protists Cell surface -Plasma membrane -Extracellular material (ECM), in some -Diatoms – Silica shells Cysts -Dormant cell with resistant outer covering -Used for disease transmission

  7. General Biology of the Protists Locomotion -Flagella -Cilia -Pseudopodia (“false feet”)

  8. General Biology of the Protists Nutrition -Phototrophs -Heterotrophs -Mixotrophs are both phototrophic and heterotrophic

  9. General Biology of the Protists Asexual reproduction -Binary fission -Budding -Schizogony = Multiple fission Sexual reproduction -Union of haploid gametes which are produced by meiosis

  10. Diplomonads and Parabasalids Diplomonads -Have two nuclei -Giardia intestinalis Parabasalids -Have undulating membranes -Trichomonas vaginalis

  11. Euglenozoa

  12. Euglenozoa Kinetoplastids -Unique, single mitochondrion with DNA maxicircles and minicircles (RNA editing) -Trypanosomes cause human diseases -African sleeping sickness – Tsetse fly -Leishmaniasis – Sand fly -Difficult to control because organisms repeatedly change their protective coat

  13. Euglenozoa

  14. Alveolata Alveolata have flattened vesicles called alveoli -These function like Golgi bodies below the cell membrane

  15. Alveolata Dinoflagellates -Unicellular with two unequal flagella -Live in aquatic environments “Blooms” are responsible for red tide -Most are photosynthetic -Do not appear to be directly related to any other phylum

  16. Alveolata Dinoflagellates -Reproduction is primarily asexual -DNA is not complexed with histones -About 20 species produce powerful toxins that harm vertebrates -

  17. Alveolata Apicomplexans -Spore-forming animal parasites -Apical complex is a unique arrangement of organelles at one end of the cell -Enables the cell to invade its host

  18. Alveolata Plasmodium -An apicomplexan that causes malaria -Eradication of malaria 1. Elimination of mosquito vectors 2. Development of drugs 3. Development of vaccines -Organism has a very complex life cycle

  19. Alveolata Otherapicomplexans -Gregarines -Found in the intestines of arthropods, annelids and mollusks -Toxoplasma gondii -Causes infections in humans with immunosuppression

  20. Alveolata Ciliates -Feature large numbers of cilia arranged in longtitudinal rows or spirals around the cell -Have two types of vacuoles -Food vacuoles = Digestion of food -Contractile vacuoles = Regulation of water balance

  21. Alveolata Ciliates -Have two types of nuclei -Macronucleus = Divides by mitosis -Responsible for physiological functions -Micronucleus = Divides by meiosis -Involved in conjugation -Fusion of two cells of different mating types

  22. Stramenopila Stramenopiles have very fine hairs on their flagella -A few species have lost their hairs during evolution

  23. Stramenopila Brown algae -Kelps -Grow in relatively shallow waters throughout the world -Life cycle involves alternation of generations -Sporophyte = Multicellular and diploid -Gametophyte = Multicellular and haploid

  24. Stramenopila Diatoms (Phylum Chrysophyta) -Unicellular organisms -Have unique double shells made of silica -Some move using raphes -Two long grooves lined with vibrating fibrils

  25. Stramenopila

  26. Stramenopila Oomycetes (“water molds”) -Were once considered fungi -Motile zoospores with two unequal flagella -Undergo sexual reproduction -Either parasites or saprobes -Phytophthora infestans -Irish potato famine (1845-1847)

  27. Rhodophyta Rhodophyta, or red algae, range from microscopic to very large sizes -Lack flagella and centrioles -Have accessory photosynthetic pigments within phycobilisomes -Origin has been a source of controversy -Tentatively, treated as a sister clade of Chlorophyta (green algae)

  28. Rhodophyta

  29. Choanoflagellida Choanoflagellates are most like the common ancestor of all animals -Single emergent flagellum, surrounded by funnel-shaped contractile collar -Use collar to feed on bacteria -Have a surface tyrosine kinase receptor found in sponges

  30. Choanoflagellida

  31. Protists Without a Clade Amoebas are paraphyletic -Rhizopoda (True amoebas) -Move by means of cytoplasmic projections called pseudopods -Actinopoda (Radiolarians) -Glassy exoskeletons made of silica -Needlelike pseudopods

  32. Protists Without a Clade

  33. Protists Without a Clade Foraminifera are heterotrophic marine protists -Have pore-studded shells called tests,through which thin podia emerge -Use podia for swimming and feeding -Have complex life cycles with haploid and diploid generations -Limestones are rich in forams -White cliffs of Dover

  34. Protists Without a Clade

  35. Protists Without a Clade Slime molds -Were once considered fungi -Include two lineages 1. Plasmodial slime molds 2. Cellular slime molds

  36. Protists Without a Clade 1. Plasmodial slime molds -Stream along as a plasmodium, a nonwalled, multinucleate mass of cytoplasm -Ingests bacteria and other organic material -When food or moisture is scarce, organism forms sporangia, where spores are produced

  37. Protists Without a Clade

  38. Protists Without a Clade 2. Cellular slime molds -Individual organisms behave as separate amoebas -Move through soil ingesting bacteria -When food is scarce, organisms aggregate to form a slug -Slug differentiates into a sorocarp

  39. Protists Without a Clade

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