Protists

1. Chapter 21 Protists

2. Protists 2 Protists are the most diverse of the four eukaryotic kingdoms Unicellular, colonial and multicellular groups The kingdom Protista is paraphyletic and grouped for convenience Catch-All Kingdom The 15 major protist phyla are grouped into seven major monophyletic groups However, 60 lineages cannot be placed with confidence

3. General Biology of the Protists 3 Cell surface Plasma membrane Extracellular material (ECM), in some Diatoms � Silica shells Cysts Dormant cell with resistant outer covering Used for disease transmission

4. General Biology of the Protists 4 Locomotion Flagella Cilia Pseudopodia (�false feet�) Lobopods � Large, blunt Filopods � Thin, branching Axopods � Thin, long

5. General Biology of the Protists 5 Nutrition Phototrophs Heterotrophs Phagotrophs � Particulate food matter Osmotrophs � Soluble food matter Mixotrophs are both phototrophic and heterotrophic

6. General Biology of the Protists 6 Asexual reproduction Typical mode of reproduction Some species have an unusual mitosis Binary fission = Equal cells Budding = Progeny cell smaller Schizogony = Multiple fission Sexual reproduction Union of haploid gametes which are produced by meiosis

7. Diplomonads and Parabasalids 7 Are closely related to the early, now extinct eukaryotic cell Flagellated Lack mitochondria May have lost their mitochondria, rather than never acquired them

8. Diplomonads and Parabasalids 8 Diplomonads Have two nuclei Giardia intestinalis Parabasalids Have undulating membranes Trichomonas vaginalis

9. Euglenozoa 9 Euglenoids were among the earliest eukaryotes to possess mitochondria 1/3rd have chloroplasts -All have a flexible pellicle None have sexual reproduction

10. Euglenozoa 10 Euglena Two anterior (and unequal) flagella Contractile vacuoles � Collect excess water Stigma � Movement towards light Numerous small chloroplasts The concept of a single Euglena genus is now being debated

11. Euglenozoa 11 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

12. Euglenozoa 12

13. Alveolata 13 Alveolata have flattened vesicles called alveoli These function like Golgi bodies below the cell membrane

14. Alveolata 14 Dinoflagellates Unicellular with two unequal flagella Live in aquatic environments Most are photosynthetic Do not appear to be directly related to any other phylum

15. Alveolata 15 Dinoflagellates Reproduction is primarily asexual DNA is not complexed with histones About 20 species produce powerful toxins that harm vertebrates �Blooms� are responsible for red tide

16. Alveolata 16 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

17. Alveolata 17 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

18. 18

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

20. Alveolata 20 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 21 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 22 Stramenopiles have very fine hairs on their flagella A few species have lost their hairs during evolution

23. Stramenopila 23 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 24 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 25

26. Stramenopila 26 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 27 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 28

29. Choanoflagellida 29 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 30

31. Protists Without a Clade 31 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 32

33. Protists Without a Clade 33 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 34

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

36. Protists Without a Clade 36 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 37

38. Protists Without a Clade 38 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 (spore-forming body)

39. Protists Without a Clade-Cellular slime mold 39