Kingdom Protista

1. Kingdom Protista Chapter 18

2. Outline • Introduction • Features of Kingdom Protista • Algae • Phylum Chlorophyta – The Green Algae • Phylum Chromophyta – The Yellow-Green Algae, Golden-Brown Algae, Diatoms, and Brown Algae • Phylum Rhodophyta – The Red Algae • Phylum Euglenophyta – The Euglenoids • Phylum Dinophyta – The Dinoflagellates • Phylum Cryptophyta – The Cryptomonads • Phylum Prymnesiophyta (Haptophyta) – The Haptophytes • Phylum Charophyta – The Stoneworts • Human and Ecological Relevance of the Algae

3. Outline cont’d. • Phylum Myxomycota – The Plasmodial Slime Molds • Phylum Dictyosteliomycota – The Cellular Slime Molds • Phylum Oomycota – The Water Molds

4. Introduction • < 1 bya, organisms confined to oceans • Protected from drying out, UV radiation, and large fluctuations in temperature • Absorbed nutrients directly from H2O • Ca. 400mya, green algae began making transition from H2O to land • Gave rise to green plants • Coleochaete probably indirect ancestor of land plants • Shares features with land plants: parenchyma-like cells, cell plate and phragmoplast during mitosis,protective covering for zygote, and production of lignin-like compound Coleochaete

5. Features of Kingdom Protista • Domain Eukarya-all members have eukaryotic cells • Includes Kingdoms Protista, Plantae, Fungi, Animalia • Organisms in Protista diverse and heterogeneous • Nutrition varied: photosynthetic, ingestion of food, absorption of food • Individual life cycles vary considerably • Reproduction generally by cell division and sexual processes • Algae in Kingdom Protista • Grouped into several phyla based on form of reproductive cells, and combinations of pigments and food reserves

6. Phylum Chlorophyta • Green Algae • Unicellular, filamentous, platelike colonies, netlike tubes, hollow spheres, lettuce-like leaves • Greatest variety in freshwater lakes, ponds, and streams • Have chlorophylls a and b • Store food as starch • Most have single nucleus per cell • Most reproduce both sexually and asexually

7. Phylum Chlorophyta • Chlamydomonas • Common in freshwater pools • Unicellular • Pair of whip-like flagella • 2 or more vacuoles at base of flagella • Regulate H2O content of cell and remove waste • Single, cup-shaped chloroplast with 1 or 2 pyrenoids inside • Pyrenoids - proteinaceous structures associated with synthesis of starch • Red eyespot near base of flagella • Allows alga to swim toward light

8. Phylum Chlorophyta Chlamydomonas

9. Phylum Chlorophyta • Chlamydomonasasexual reproduction: • Nucleus divides by mitosis, and cell contents become 2 daughter cells within cellulose wall • Each develop flagella and swim away • No change in chromosome number; all cells 1n

10. Phylum Chlorophyta • Chlamydomonassexual reproduction:

11. Phylum Chlorophyta • Ulothrix • Filamentous with holdfast cell at one end • Single, wide, curved,somewhat flattened chloroplast, with 1-several pyrenoids

12. Phylum Chlorophyta • Spirogyra (watersilk) • Filaments of cylindrical cells • Frequently floats in masses on surface of quiet freshwater • Chloroplast ribbon-shaped and spirally wrapped around vacuole, with pyrenoids at regular intervals • Asexual reproduction by fragmentation of filament

13. Phylum Chlorophyta • Spirogyra(watersilk) cont’d. • Sexual reproduction by conjugation

14. Phylum Chlorophyta • Oedogonium • Epiphytic filamentous green alga with holdfast • Large netlike chloroplast with pyrenoids at intersections of net • Asexual reproduction by fragmentation or by zoospores • Zoospores produced singly in cells at tips of filaments and have ca. 120 flagella forming fringe at one end • Sexual reproduction by oogamy - 1 gamete motile and other stationary and large

15. Phylum Chlorophyta • Oedogoniumsexual reproduction

16. Phylum Chlorophyta • Other green algae • Chlorella -widespread green alga composed of tiny spherical cells • Only reproduce asexually by forming either daughter cells or autosporesthrough mitosis • Used in research; may become important as food source • Desmids -mostly free-floating and unicellular • Reproduce by conjugation Closterium, a desmid

17. Phylum Chlorophyta • Other green algae cont’d. • Hydrodictyon (water nets) -net-like, tubular colonies with hexagonal or polygonal meshes • Asexual reproduction and isogamoussexual reproduction • Isogamous - 2 flagellated gametes

18. Phylum Chlorophyta • Other green algae cont’d. • Acetabularia(mermaid’s wineglass) -consists of single, huge cell shaped like delicate mushroom • Used in classic experiments demonstrating influence of nucleus on form of cell • Isogamous sexual reproduction

19. Phylum Chlorophyta • Other green algae cont’d. • Volvox -colonial green algae held together insecretion of gelatinous material, resembling hollow ball • Reproduction asexual or sexual • Smaller daughter colonies formed inside parent colony

20. Phylum Chlorophyta • Other green algae cont’d. • Ulva (sea lettuce) -multicellularseaweed with flattened green blades and basal holdfast to anchor blades to rocks • 1nand 2nblades • 2nblades produce spores developing into 1n blades • 1nblades bear gametangia - form gametes • Zygotes grow into 2n blades • 1nand 2nblades indistinguishable = isomorphic

21. Phylum Chromophyta • Yellow-green algae (Xanthophyceae) • Mostly freshwater, with few marine and terrestrial species • 2 flagella of motile cells oriented in opposite directions • Vaucheria - Oogamous, coenocytic, filamentous species • Aplanospores formed during asexual reproduction • Sexual reproduction rare Stipitococcus, a yellow-green algae Sexual reproduction in Vaucheria

22. Phylum Chromophyta • Golden-brown algae (Chrysophyceae) • Most occur in plankton of fresh H2O • Motile cells have 2 flagella of unequal length inserted at right angles to each other • Photoreceptor on short flagellum

23. Phylum Chromophyta • Diatoms (Bacillariophyceae) • Unicellular • Fresh and salt H2O, particularly abundant in cold marine habitats • Dominate algal flora on damp cliffs, tree bark or buildings • Look like ornate, glass boxes with lids • 95% of wallsilica • Chlorophylls a and c and fucoxanthin • Food reserves = oil, fats or laminarin

24. Phylum Chromophyta • Diatoms (Bacillariophyceae) cont’d.

25. Phylum Chromophyta • Brown algae (Phaeophyceae) • Relatively large; none unicellular or colonial • Most marine; majority in cold, shallow H2O • Many havethallusdifferentiated intoholdfast,stipe, and blades • Blades may have gas-filled bladders • Chlorophylls a and c, fucoxanthin • Food reserve = laminarin • Algin in cell walls Nereocystis, a kelp

26. Phylum Chromophyta • Brown algae (Phaeophyceae) cont’d. • Sargassum -floating brown seaweed • Asexual reproduction by fragmentation or autospores Sargassum

27. Phylum Chromophyta • Brown algae (Phaeophyceae) • Fucus(Common rockweed) • Sexual reproduction

28. Phylum Rhodophyta • Red algae • In warmer and deeper waters than brown algae • Most filamentous with filaments so tightly packed they appear to have flattened blades or branched segments

29. Phylum Rhodophyta • Red algae cont’d. • Relatively complex life cycle involving 3 types of thallus structures • Nonmotile reproductive cells

30. Phylum Rhodophyta • Red algae cont’d. • Colors mostly due to phycobilins • Similar to those of cyanobacteria • Red algae may have been derived from cyanobacteria • Chlorophylls a, c,and sometimes d • Food reserve - Florideanstarch • Numbers of species produce agar

31. Phylum Euglenophyta • Euglenoids • No cell wall; pellicle = plasma membrane and underlying strips that spiral around cell • Flagellum • Gullet ingests food • Ca. 1/3 of species have disc-shaped chloroplasts • Red eyespot for light detection • Paramylon food reserve • Asexual reproduction by cell division. • Sexual reproduction not confirmed

32. Phylum Dinophyta • Dinoflagellates • Red tides -sudden multiplication of dinoflagellates • Some produce neurotoxins that accumulate in shell fish • Cellulose “armor plates” inside cell membrane • 2 flagella in intersecting grooves • One acts as rudder • Other gives cell spinning motion

33. Phylum Dinophyta • Dinoflagellates cont’d. • Most have disc-shaped chloroplasts • Contain xanthophyllpigments • Chlorophylls a and c • Ca. 45% non-photosynthetic • Chromosomes remain condensed and visible throughout life of cell • Food reserve = starch • Many have tiny projectiles that fire when irritated

34. Phylum Cryptophyta • Cryptomonads • Marine and freshwater • 2 flagella • Plates on inside of plasma membrane • Single, 2-lobed chloroplast with starch granules surrounding central pyrenoid • Nucleomorph -estigialnucleus of primitive symbiotic organism • Gullet with ejectosomes - aid in propulsion • Sexual reproduction unknown

35. Phylum Prymnesiophyta (Haptophyta) • Haptophytes • Fresh and saltwater; major component of marine plankton • Most unicellular, with 2 smooth flagella of similar length inserted at apex • Pigments and food reserve similar to Chromophyta • Haptonema – 3rd flagellum located between 2 flagella • Aids in food capture • Often covered in scales • 2 disc-shaped chloroplasts

36. Phylum Charophyta • Stoneworts • Shallow, freshwater lakes and ponds • Often precipitate Ca salts on surfaces • Axis with short lateral branches in whorls • Sexual reproduction is oogamous • Multicellular antheridia

37. Human and Ecological Relevance of Algae • Protistan algal phyla at bottom of food chain • Diatoms • Oils sources of vitamins • Diatomaceous earth • Filtration • Polishes, toothpaste • Paint that reflects light • Other algae • Chlorella • Potential human food source

38. Human and Ecological Relevance of Algae • Algin • Produced by giant kelps and other brown algae • Ice cream, salad dressing • Latex paint, textiles, ceramics • Regulates H2O behavior • Controls development of ice crystals • Regulates penetration of water • Stabilizes suspensions Vessel harvesting kelp

39. Human and Ecological Relevance of Algae • Minerals and food • Iodine from kelp • Red algae • Food - Dulse, nori • Carrageenan -thickening agent • Agar • Produced by red alga Gelidium • Solidifier of nutrient culture media • Retains moistness in bakery products • Base for cosmetics

40. Phylum Myxomycota • Plasmodialslime molds • Without chlorophyll • Feed on bacteria and other organic particles • Consist ofplasmodium • Protoplasm containing many 2nnuclei • No cell wall • Flows rapidly and rhythmically • Found on damp forest debris, under logs, on dead organic material Plasmodium

41. Phylum Myxomycota • Plasmodialslime molds cont’d. • Sexual reproduction: • Plasmodium converts into separate small sporangia containing spores Sporangia from various plasmodial slime molds

42. Phylum Myxomycota • Plasmodialslime molds cont’d. • Sexual reproduction of plasmodial slime mold:

43. Phylum Dictyosteliomycota • Cellular slime molds • Individual amoebalike cells feed independently, dividing and producing separate new cells periodically • Clump together to form mass called pseudoplasmodium • Crawls like a garden slug • Eventually transforms into sporangium-like mass of spores • Human and ecological relevance of the slime molds • Break down organic particles to simpler substances

44. Phylum Oomycota • Water molds • Cottony growths on fish; often found on dead insects • Range in form from single spherical cells to branching, threadlike, coenocytichyphae • Coenocytichyphae not divided into individual cells and may form large thread masses (mycelia) • Share features with brown algae, including oogamy, cellulose in cell walls, predominantly 2nlifecycle, and zoospores with 2 flagella • Asexual reproduction: • Crosswalls form at tips of hyphae • Zoospores produced inside and emerge through pore

45. Phylum Oomycota • Water molds cont’d. • Sexual reproduction: • Meiosis takes place in oogonia and antheridia • Zygotes formed in oogonia give rise to new mycelia • Human and ecological significance of water molds: • Downy mildew on grapes • Potato blight

46. Review • Introduction • Features of Kingdom Protista • Algae • Phylum Chlorophyta – The Green Algae • Phylum Chromophyta – The Yellow-Green Algae, Golden-Brown Algae, Diatoms, and Brown Algae • Phylum Rhodophyta – The Red Algae • Phylum Euglenophyta – The Euglenoids • Phylum Dinophyta – The Dinoflagellates • Phylum Cryptophyta – The Cryptomonads • Phylum Prymnesiophyta (Haptophyta) – The Haptophytes • Phylum Charophyta – The Stoneworts • Human and Ecological Relevance of the Algae

47. Review cont’d. • Phylum Myxomycota – The Plasmodial Slime Molds • Phylum Dictyosteliomycota – The Cellular Slime Molds • Phylum Oomycota – The Water Molds