Kingdom Protista

1. Kingdom Protista Protists

2. 50 m • Even a low-power microscope • Can reveal an astonishing menagerie of organisms in a drop of pond water

3. Protist Diversity • Protists are more diverse than all other eukaryotes • And are no longer classified in a single kingdom • Most protists are unicellular • And some are colonial or multi-cellular

4. Protist Diversity • Organisms that range in size from single cells to complex structures more than 100 meters long. • They show a variety of reproductive and nutritional strategies.

5. Protist Diversity • 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

6. (a) The freshwater ciliate Stentor,a unicellular protozoan (LM) 100 m 100 m (b) Ceratium tripos, a unicellular marine dinoflagellate (LM) 4 cm (c) Delesseria sanguinea, a multicellular marine red alga 500 m (d) Spirogyra, a filamentous freshwater green alga (inset LM) • Protists are also diverse in habitat • Including freshwater and marine species

8. ProtistA Evolution • There is now considerable evidence • That much of protist diversity has its origins in endosymbiosis

9. ProtistA Evolution • The plastid-bearing lineage of protists • Evolved into red algae and green algae • On several occasions during eukaryotic evolution • Red algae and green algae underwent secondary endosymbiosis, in which they themselves were ingested

10. Plastid Dinoflagellates Alveolates Apicomplexans Secondary endosymbiosis Cyanobacterium Ciliates Red algae Primary endosymbiosis Stramenopiles Heterotrophic eukaryote Plastid Euglenids Secondary endosymbiosis Green algae Chlorarachniophytes 2˚ Endosymbiosis

11. Diplomonadida and parabasala • Have modified mitochondria • Are adapted to anaerobic environments • Lack plastids • Have mitochondria that lack DNA, an electron transport chain, or citric-acid cycle enzymes • A tentative phylogeny of eukaryotes • Divides eukaryotes into many clades

12. 5 µm (a) Giardia intestinalis, a diplomonad (colorized SEM) • Diplomonads • Have two nuclei and multiple flagella

13. Zooflagellates ·Move by flagella ·They may enter into symbiotic relationships with other organisms.

14. Parabasalids • -include trichomonads • Which move by means of flagella and an undulating part of the plasma membrane

15. Euglenozoa • Have flagella with a unique internal structure • Euglenozoa is a diverse clade that includes • Predatory heterotrophs, photosynthetic autotrophs, and pathogenic parasites • 2 Types • Kinetoplastids & Euglenids

16. Flagella 0.2 µm Crystalline rod Ring of microtubules Euglenozoa • The main feature that distinguishes protists in this clade • Is the presence of a spiral or crystalline rod of unknown function inside their flagella

17. 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 Kinetoplastids

19. 9 m Tsetse fly Trypanosoma • Causes sleeping sickness in humans

20. Long flagellum Eyespot: pigmented organelle that functions as a light shield, allowing light from only a certain direction to strike the light detector Light detector: swelling near the base of the long flagellum; detects light that is not blocked by the eyespot; as a result, Euglena moves toward light of appropriate intensity, an important adaptation that enhances photosynthesis Short flagellum Contractile vacuole Nucleus Euglena (LM) 5 µm Plasma membrane Pellicle: protein bands beneath the plasma membrane that provide strength and flexibility (Euglena lacks a cell wall) Chloroplast Figure 28.8 Paramylon granule Euglenids

21. Euglenids

22. Euglenids Only one third of the species of Euglenoids are photosynthetic. ·Euglena stores glucose in a polymer called Paramylon · An eyespot with a photoreceptor is capable of detecting the presence of light. · Reproduction is asexual.

23. Alveoli 0.2 µm Flagellum Alveolates • Members of the clade Alveolata • Have membrane-bounded sacs (alveoli) just under the plasma membrane • Includes: • Dinoflagellates • Apicomplexans • Ciliates

24. Dinoflagellates • Are a diverse group of aquatic photoautotrophs and heterotrophs • Are abundant components of both marine and freshwater phytoplankton • Shape is reinforced by internal plates of cellulose • Two flagella • Make them spin as they • move through the water

25. Dinoflagellates Some species are responsible for red tides that kill fish and shellfish Toxins released can kill aquatic & terrestrial animals (aerosols)

26. Apicomplexans • Are parasites of animals and some cause serious human diseases • Are so named because one end, the apex, contains a complex of organelles specialized for penetrating host cells and tissues • Have a non-photosynthetic plastid, the apicoplast

27. Apicomplexans Most apicomplexans have intricate life cycles • With both sexual and asexual stages that often require two or more different host species for completion • Plasmodium causes malaria

28. Plasmodium Anopheles mosquito

29. Sporozoans • Parasitic • Complicated life cycle that usually involves the formation of infective spores. e.g. malaria - The parasite is injected into a human by a mosquito. The parasite then invades red blood cells and ruptures them.

30. Ciliates • Are named for their use of cilia to move and feed • Have large macronuclei and small micronuclei • The micronuclei • Function during conjugation, a sexual process that produces genetic variation • Conjugation is separate from reproduction • Which generally occurs by binary fission

31. Ciliates • Example - Paramecium • The outer covering of paramecium is covered with hundreds of cilia • They have numerous organelles including a gullet (oral groove) and an anal pore • The macronucleus controls the cell's activities. • The micronucleus is involved in cell reproduction (sexual & asexual).

32. CONJUGATION AND REPRODUCTION 2 MEIOSIS Macronucleus Haploidmicronucleus Compatiblemates Diploidmicronucleus Diploidmicronucleus MICRONUCLEARFUSION 7 8 Key Conjugation Reproduction Meiosis of micronuclei produces four haploidmicronuclei in each cell. 3 micronuclei in each cell disintegrate. The remaining micro-nucleus in each cell divides by mitosis The cells swap one micronucleus The cellsseparate Micronuclei fuse,forming a diploid micronucleus. Two rounds of cytokinesis partition one macronucleus and one micronucleus into each of four daughter cells. The original macro-nucleus disintegrates. Four micronuclei become macronuclei, while the other four remain micronuclei. Three rounds of mitosis without cytokinesis produce eight micronuclei.

33. Paramecium

35. 50 µm FEEDING, WASTE REMOVAL, AND WATER BALANCE

36. Stentor (Type of ciliate)

37. Hairy flagellum Smooth flagellum 5 µm Stramenopila • Stramenopiles have “hairy” and smooth flagella • The clade Stramenopila Includes: • Water molds • Diatoms • Golden algae • Brown algae

38. Oomycetes • Include water molds, white rusts, and downy mildews • Were once considered fungi based on morphological studies • Are decomposers or parasites • Have filaments (hyphae) that facilitate nutrient uptake • Have cell walls made of cellulose

39. 3 µm Diatoms • Are unicellular algae • With a unique two-part, glass-like wall of hydrated silica • major component of phytoplankton

40. Diatoms ·Most numerous unicellular algae in the oceans and are an important source of food and oxygen. ·Also important in freshwater environments. ·Glucose stored as polysaccharide laminarin (Same as golden & brown algae) ·Their remains form diatomaceous earth.

41. 50 µm Diatoms ~ 100 000 species

42. 25 µm Golden Algae • Or chrysophytes • Are named for their color, which results from their yellow & brown carotenoids • The cells of golden algae • Are typically bi-flagellated, with both flagella attached near one end of the cell

43. Brown algae • Or phaeophytes • Are the largest and most complex algae • Are all multicellular, and most are marine • Include many of the species commonly called seaweeds • Seaweeds • Have the most complex multi-cellular anatomy of all algae

44. Blade Stipe Holdfast Brown Algae Photosynthetic&multicellular ·Range in size. Many are 50-100 m long. ·Found along rocky shores The thalus (plant like body) contains: ·Holdfasts for attachment ·Blades and air bladders that function in floatation ·A stem-like structure that holds the blades is called a stipe. Fucus Common "seaweed" found along the rocky coast.

45. Brown Algae

46. Kelps, or giant seaweeds • Live in deep parts of the ocean • Can grow as long as 60m Cell walls are composed of cellulose and gel forming polysaccharides which cushion the algae in the intertidal zone

47. Brown Algae - Macrocystis and Nereocystis (Deep water Kelp) Nereocystis Macrocystis

48. Sporangia MEIOSIS Sporophyte (2n) Zoospores Female Developing sporophyte Gametophytes (n) Zygote (2n) Egg Male FERTILIZATION Mature female gametophyte (n) Sperm Key Haploid (n) Diploid (2n) A variety of life cyclesHave evolved among the multi-cellular algae • The most complex life cycles include an alternation of generations • The alternation of multi-cellular haploid and diploid forms

49. Cercozoans • Cercozoans and radiolarians have threadlike pseudopodia • A newly recognized clade, Cercozoa • Contains a diversity of species that are among the organisms referred to as amoebas • Amoebas were formerly defined as protists • That move and feed by means of pseudopodia • Cercozoans are distinguished from most other amoebas

50. 20 µm Foraminiferans, or forams • Are named for their porous, generally multichambered shells, called tests Pseudopodia extend through the pores in the test