Protists are a diverse group of eukaryotic organisms that cannot be classified as plants, animals, fungi or bacteria. They include both single-celled and multi-cellular organisms, and exhibit characteristics of plants, animals and fungi. Protists are divided into groups based on these characteristics, including plant-like protists such as algae, animal-like protists such as protozoa, and fungus-like protists such as slime molds. They serve important ecological roles including as primary producers through photosynthesis and as decomposers.

1. Protists Classifying the Exceptions

2. What are Protists? Those organisms that cannot be classified as Monerans, fungi, plants or animals Created as a group because of classification problems Some share characteristics of more than one other kingdom Example: Euglena has chloroplasts & is an autotroph like plants, but has no cell wall and can swim using a flagella, so also like an animal

3. Characteristics of Protists Almost all are unicellular A few are colonies of identical cells Are distinguished from unicellular Monerans because they are eukaryotes Have a nuclear membrane Have mitochondria and other organelles A diverse group with diverse characteristics some are plant-like, autotrophs  algae some are animal-like, heterotrophs  protozoans some are fungus-like, decomposers  slime molds

4. Plant-like Protists 10,000 species of plant-like protists Divided into 3 phyla Phylum Euglenophyta Phylum Pyrrophyta dinoflagelates, plankton Phylum Chrysophyta diatoms

5. Phylum Euglenophyta Most have chloroplasts - are autotrophs Have a large nucleus and nucleolus Have large chloroplasts these disappear if the organism is placed in the dark No cell wall on the outer surface of the cell are spiral strips of protein which form a pellicle - give cell shape Can move by changing shape Have 2 flagella: one long, one short Have an eye spot an area of red pigment that is sensitive to light A gullet opens into reservoir Reproduce asexually

6. Euglenoids

7. Freshwater Protists Euglenoids live in fresh water ponds and lakes The single-celled organism is in a hypotonic solution Water diffuses in by osmosis No rigid cell wall These organisms have to have an other means to prevent the cell membrane from bursting Contractile vacuole controls water balance Pumps excess water back out of the cell

8. The Contractile Vacuole

9. Phylum Pyrrophyta Most common are dinoflagellates Unicellular algae with 2 flagella Most are marine Many plankton (small organisms near the surface of the ocean) are dinoflagelates Mitosis is somewhat like prokaryotes some scientists believe are intermediate form between prokaryotes and eukaryotes

10. Dinoflagellate Characteristics Most have chloroplasts with chlorophyll red & yellow pigments mask the green Most have a cellulose cell wall Segments fit together like armor Most have 2 flagella One extends back from the middle of the cell - propels the organism 2nd wraps around middle in a groove - vibrates causing cell to spin Chromosomes are visible in dinoflagellates Some produce toxins - red tide! Many produce light - bioluminescence

11. A Dinoflagellate

12. Phylum Chrysophyta Most are diatoms - live in fresh and salt water Most are photosynthetic Most are gold or brown from pigments other than chlorophyl Most don't have flagella Have cell walls with 2 overlapping halves composed of pectin - a gelatinous material; also contains silica Reproduce a sexually

13. Diatoms

14. Multi-cellular Algae Many algae have multi-cellular bodies Body of a multi-cellular algae = thallus Once classified as plants because they have chlorophyll and perform photosynthesis Now usually classified as protists because they have reproductive structures different from plants Three phyla: Chlorophyta = green algae Rhodophyra = red algae Phaeophyta = brown algae

15. Red Algae

16. Volvox – A Colonial Green Algae

17. Spirogyra Conjugation

18. Kelp – A Brown Algae

19. Protozoans Animal-like protists Are heterotrophs Can move Classified by their means of movement Four diverse groups: Sarcodinians Zooflagellates Ciliaphorans Sporozoans

20. Sarcodinians Protozoans that move by extending lobes of cytoplasm Pseudopods = false feet Example: amoeba Some have hard shells of calcium carbonate or silica Extend pseudopods through holes in their shells Examples: foraminferans & radiolarians

21. The Amoeba

22. Radiolarian

23. Heliozoan

24. Zooflagellates Protozoans that move by means of a flagella Many are free-living freshwater or marine organisms Many live in symbiotic relationships with other organisms Example: Trichonympha live in the guts of termites and digest cellulose Some are parasites that cause disease Example: Trypanosoma causes African sleeping sickness

25. Trypanosomes

26. Trichomona

27. Ciliaphorans Protozoans covered with hair like projections, cilia, used to move The largest and most diverse group Examples: Paramecium Stentor

28. The Paramecium

29. Sporozoans Have no structures for movement Live as parasites on other animals Spore-forming parasitic protozoans Have complex life cycles that include both sexual and asexual phases Some cause human diseases Example: plasmodium causes malarial carried by mosquitos

30. Fungus-like Protists Live in damp, watery places Decomposers Extract nutrients from dead organisms Three groups: Plasmodial slime molds Cellular slime molds Water molds

31. Plasmodial Slime Molds Have different forms at different stages in their life cycle Plasmodium = feeding stage Forms a fruiting body that produces spores Spores unite to form amoeboid zygote  the second stage Mitosis of the zygote regenerates the plasmodium

32. Slime Mold

33. Cellular Slime Molds Live in fresh water, damp soil, or decomposing plant material Also alternate between an amoeboid form and a spore-producing fruiting body Amoeboid stage is the feeding stage Reverse of plasmodial slime molds Amoeboid stage can produce a pseudoplasmodium “ Pseudo” because the individual cells are still independent Pseudoplasmodium produces fruiting bodies Fruiting bodies produce spores

34. Water Molds Used to be classified as fungi Fungi have cell walls that contain chitin Water molds have cell wall of cellulose Water molds produce spores with flagella Fungi produce spores without flagella Are decomposers or parasites Includes water molds, white rusts, downy mildews Potato blight

35. Powdery Mildew