Chapter 20 The Protists (Sections 20.1 - 20.4)

1. Chapter 20The Protists (Sections 20.1 - 20.4)

2. 20.1 Harmful Algal Blooms • Aquatic protists include single-celled and multicellular autotrophs and heterotrophs • An algal bloom is a population explosion of an aquatic protist, or of another aquatic microorganism • Toxins released during some algal blooms can harm wildlife and endanger human health

3. Key Terms • protist • Eukaryote that is not a fungus, animal, or plant • algal bloom • Population explosion of tiny aquatic producers • toxin • Chemical that is made by one organism and harms another

4. Karenia brevis • This dinoflagellate produces brevetoxin, which interferes with nerve cells of people and animals who inhale or ingest it

5. 20.2 A Collection of Lineages • Protists are a collection of mostly single-celled eukaryotes • Many have chloroplasts that evolved from cyanobacteria or another protist • The dominant stage of the life cycle may be haploid or diploid • Protists are not a natural group, but a collection of lineages, some only distantly related to one another

6. Protist Diversity

7. Protist Diversity Fig. 20.2a, p. 312

8. Protist Diversity Fig. 20.2b, p. 312

9. Protist Diversity Fig. 20.2c, p. 312

10. Protist Diversity Fig. 20.2d, p. 312

11. Protist Diversity Fig. 20.2e, p. 312

12. Protist Groups • Protists are not a single lineage • One proposed eukaryotic family tree with protist groups indicated by tan boxes

13. Protist Groups diplomonads parabasalids Flagellated Protozoans trypanosomes euglenoids radiolarians foraminiferans ancestral cells ciliates dinoflagellates Alveolates apicomplexans water molds diatoms Stramenopiles brown algae red algae chlorophyte algae Green Algae charophyte algae land plants amoebas Amoebozoans slime molds fungi choanoflagellates animals F Fig. 20.2f, p. 312

14. Key Concepts • A Collection of Lineages • Protists include many lineages of eukaryotic organisms, some autotrophs and others heterotrophs • Protists are not a clade; some groups are more closely related to plants, or to fungi and animals, than to other protists

15. 20.3 Flagellated Protozoans • Flagellated protozoans are single cells with no cell wall – a protein covering (pellicle) helps maintain the cell’s shape • flagellated protozoan • Protist belonging to an entirely or mostly heterotrophic lineage with no cell wall and one or more flagella • pellicle • Layer of proteins that gives shape to many unwalled, single-celled protists

16. Diplomonads and Parabasalids • Diplomonads and parabasalids have multiple flagella and are adapted to oxygen-poor habitats • Instead of mitochondria, they have organelles that produce ATP by an anaerobic pathway • Both groups include species that infect humans

17. A Diplomonad • Diplomonads have two more or less identical nuclei • Giardia lamblia causes giardiasis, a waterborne intestinal disease

18. A Parabasalid • Trichomonas vaginalis causes a sexually transmitted disease

19. Trypanosomes • trypanosome • Parasitic flagellate with a single mitochondrion and a membrane-encased flagellum • Insects transmit trypanosomes, such as Trypanosoma brucei, which causes African sleeping sickness

20. Euglenoids • euglenoid • Flagellated protozoan with multiple mitochondria • Some have chloroplasts that evolved by secondary endosymbiosis from a green alga • Typically live in fresh water • Have a contractile vacuole • contractile vacuole • In freshwater protists, an organelle that collects and expels excess water

21. Body Plan of Euglena

22. Body Plan of Euglena long flagellum chloroplast contractile vacuole eyespot ER nucleus pellicle Golgi body mitochondrion Fig. 20.4, p. 313

23. ANIMATION: Body plan of Euglena To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERE

24. 20.4 Mineral-Shelled Protozoans • Foraminiferans and radiolarians are single-celled marine protists with sieve-like shells • They capture food with microtubule-reinforced cytoplasmic extensions that protrude through the shell’s openings • Both are marine heterotrophs and may be part of plankton • plankton • Community of tiny drifting or swimming organisms

25. Foraminiferans and Radiolarians • foraminiferan • Heterotrophic single-celled protist with a chalky calcium carbonate shell and long cytoplasmic extensions • Deposits of their remains are mined for chalk and limestone • radiolarian • Heterotrophic single-celled protist with a glassy silica shell and long cytoplasmic extensions that stick out through the porous shell and capture prey

26. Foraminiferans and Radiolarians

27. Foraminiferans and Radiolarians Fig. 20.5a, p. 314

28. Foraminiferans and Radiolarians Fig. 20.5b, p. 314

29. Foraminiferans and Radiolarians Fig. 20.5c, p. 314