Chapter 20 Protists

1. Chapter 20 Protists Isosporafelis

2. Some Protist Basics • Domain: Eukarya • Kindgom: Protista • Cell wall composition: various • Prokaryotic or Eukaryotic: Eukaryotic • Examples: • **Mostly Unicellular**

3. What’s in a name? • Derived from Greek word meaning “The Very First” – Proto

4. Characteristics: • Eukaryotic • Mostly unicellular - may be Colonial (Spirogyra and Volvox) • Plant-like, Animal-like, or Fungus-like characteristics

5. Where did they come from? • Lynn Margulis’ Endosymbiont Hypothesis – Present day protists evolved from the symbiotic relationship of prokaryotes that lived together until eventually, they had to remain together.

6. Where did they come from? • Used organelle evidence: • Mitochondria and chloroplasts are actually Eubacteria & blue-green bacteria (now Archaeabacteria). • Flagella were spirochetes • Further proof provide by the algae, Cyanophora paradoxa when their chloroplasts were removed, they were actually blue-green bacteria which were able to reproduce & multiply

9. Animal-like Protists • Protozoans – First animals • Classification is based on method of mobility

10. Protozoan Structures • Contractile vacuole– Regulates water pressure • Trichocysts – defense mechanisms • Macronucleus – binary fission • Micronucleus – Conjugation • Gullet – food is packaged into food vacuoles • Oral groove – cilia lined to sweep food into gullet

11. Phylum Ciliophora • Ciliophora – Paramecium, Stentor, Didinium, Vorticella • Use cilia to move

12. Mastigophora • Giardia (Giardiasis) and Chilomonas • Have flagella for mobility • Many are parasitic and cause intestinal distress

13. Apicomplexa • Plasmodium (Malaria) and Trypanosoma (African Sleeping sickness) • Nonmotile • Reproduce by forming spores in host cells

14. Sarcodina • Amoeba, Radiolarians and Formanifera • Move using pseudopods or false feet • Pseudopods are used for movement and phagocytosis of food

15. Amoeba

16. Reproduction • Most Protozoa reproduce by binary fission & conjugation

17. Feeding • Sarcodines – Phagocytosis into a vacuole which fuses with a lysosome where digestion takes place. Undigestables exit via exocytosis

18. Feeding • Ciliates actively hunt food and ingest them via an oral groove. Using cilia, they create a current to sweep food into oral groove, into gullet and then into a food vacuole.

19. Plant-like Protists Classified by their main pigment • Euglenophyta – Euglena • Move using Flagella • Eyespot as a photoreceptor to keep organism in photic zone • May be auto or heterotrophic

20. Plant-like Protists • Pyrrophyta – Fire algae Dinoflagellates • 2 flagella • Luminescent – gives off light • Produce a neurotoxin – cause Red Tides when they bloom and Paralytic Shellfish poisoning in clams and oysters. (blooms concentrate in shell fish then into fish which we eat)

21. Red Tides • Caused by a bloom in Dinoflagellates, Karenia (Gymnodinium) breve • Produce neurotoxins • Responsible for large die-offs of marine organisms and seabirds Karenia brevis

22. Plant-like Protists 3. Chrysophyta – Golden brown algae • Diatoms • Silica shell • Diatomaceous earth as filtering and also abrasives • Store food as oil (buoyancy)

23. Plant-like Protists 4. Chlorophyta—Green algae • Volvox and Spirogyra May have flagella or be immobile like Spirogyra • Main pigment is Chlorophyll a & b

24. Fungus-like Protists • Slime molds – Found in nutrient rich areas like mulch, compost and thick wet lawns. • 2 stages in life • Single amoeba-like cells • Mold-like mass that produce spores • Witches’ butter