Chapter 28: Protists

1. Chapter 28: Protists The Kingdom that no one knows what to do with

2. Lynne Margulis – 1981Endosymbiont Hypothesis • "Life did not take over the globe by combat, but by networking“ • She considers Darwin's notion of evolution driven by competition to be incomplete. • Proposed that the first eukaryotic cells originated through endosymbiosis with prokaryotic cells. • Suggests a monophyletic origin (same ancestral cells) • Mitochondria and Chloroplasts both have double membranes, circular DNA and small ribosomes. Both reproduce by binary fission. Both are about the same size as average bacteria • Purple bacteria - Mitochondria • Cyanobacteria - Chloroplasts

3. Endosymbiont Hypothesis Simplified diagrams of serial phagocytosis of purple and photosynthetic bacteria, leading to Primary endosymbioticaccommodations. 1. Ancestral prokaryote, undergoes 2. Infoldingsof plasma membrane, which permits 3. Development of nuclear membrane and endomembranous system 4. Engulfment of aerobic heterotrophic prokaryotes, generates 5. Ancestral heterotrophic eukaryote with mitochondria. Next, an ancestral heterotropiceukaryote (5) undergoes (Secondaryendosymbiosis) 6. Serial engulfment of photosynthetic prokaryotes, which generates 7. Ancestral photosynthetic eukaryote with plastids.

4. Animation

5. Characteristicsof Protist • Least clearly defined & most diverse of all kingdoms • Paraphyletic – not closely related to one another but share some characteristics due to common ancestry. • Unicellular, filamentous, and colonial w/ some being multicellular • Most are microscopic & a few like Kelp are HUGE • Photosynthetic, heterotrophic ormixotrophs(both) • Plant-like (Algae), animal-like (Protozoa) and fungus-like (Slime molds and water molds) characteristics • Aquatic (marine and freshwater), in the soil, symbionts in the digestive tract of animals and parasitic. • Some are immobile, some move by amoeboid motion, some have flagella and some have cilia

6. Paramecium Spirogyra Giardia Volvox Slime mold Euglena Amoeba Diatom Plasmodium Kelp

7. Phylogenetic Tree Amoeba Paramecium Euglena Giardia

10. Bacillariophyta

12. Influence on Environment • Dinoflagellates • Marine and Freshwater. • Blooms • Produce toxins causing Paralytic Shellfish poisoning • Bioluminescent • Apicomplexa are parasites in animals. • Produce Sporozoites • Intricate life cycle of both sexual and asexual stages • Plasmodiumthat causes malaria carried by the Anophelesvector

13. Video 1Video 2 RBC

14. Ciliates • Have cilia covering all or part of their pellicle • Have Macronuclei (binary fission) and Micronuclei (conjugation) • Contractile vacuoles to regulate osmotic pressure • Video

15. Diatoms • Bacillariophyta • Have a silica shell provides protection from predators • Major component of phytoplankton • Diatomaceous earth used as a filtering medium • Abrasives

16. Seaweeds Phaeophyta (brown algae), Rhodophyta (red algae) and Chlorophyta (green algae) Used as food source Laminaria – in soups Porphyra – nori are the thin sushi wraps Agar Thickening agent in pudding, ice cream &salad dressing Ulva – sea lettuce is dried or eaten fresh

17. Oomycetes: Water Molds Oh the Oomycetes! Fungus like protists with cells walls of cellulose (chitin in fungus) and is basically diploid most of its life cycle (fungus are basically haploid). Have flagellated reproductive cells Filamentous like the hyphae of fungus Ich on fish and “mold” on moist fruit Caused TheGreat Potato blight of 1840’s in Ireland. Phytophthorainfestans Destroys 15% of North American crops & 70% in Russia!