Classification II Protista & Fungi

1. Classification IIProtista & Fungi AP Biology

2. Kingdom Protista • This kingdom of the domain Eukarya, is a kingdom of convenience • Little is known of the evolutionary relationships of its members • Similar features are just as likely to be due to convergent evolution as they are due to recent common ancestry • Protists can be algae/plant-like, animal-like, fungus-like, unicellular, or occasionally multicellular

3. Algae-Like Protists (or Plant-Like) • Autotrophic; obtain energy via photosynthesis • 1. Euglenophyta (euglenoids) • 1-3 Flagella • Can become heterotrophic in darkness • Eyespot: phototaxis • 2. Dinoflagellata (dinoflagellates) • 2 Flagella • Some bioluminescent • Some produce nerve toxins which accumulate in shellfish & can cause illness

4. Algae-Like Protists (or Plant-Like) • 3. Chrysophyta (golden algae) • 2 Flagella • Golden or Yellow • 4. Bacillariophyta (diatoms) • Have tests (shells) with silica (SiO2) • 5. Chlorophyta (green algae) • Contain chlorophyll a and b • Cellulose cell walls • Various gamete types • Form colonies (some large – volvox) • Ancestors of plants?

5. Algae-Like Protists (or Plant-Like) • 6. Phaeophyta (brown algae) • Multicellular • Flagellated sperm cells • Seaweeds, Kelps • 7. Rhodophyta (red algae) • Red accessory pigments (phycobilins) • Multicellular • Gametes have no flagella

6. Animal-Like Protists (Protozoa) • Heterotrophic; get energy from living things or dead organic matter • 1. Rhizopoda (Amoebas) • Move by extensions of the body called pseudopodia (also encircles food and absorbs via phagocytosis) • 2. Foraminifera (Forams) • Have tests usually made of calcium carbonate • Ancient marine deposits rich in certain foram tests are good indicators of underlying oil deposits

7. Animal-Like Protists (Protozoa) • 3. Zoomastigophora (zooflagellates) • Some mutualistically digest cellulose in the guts of termites • Others are parasites: Trypanosoma is one transmitted by tsetse flies and causes African sleeping sickness • 4. Sporozoa • Parasites of animals • No physical means of motility • Form spores that can be dispersed and live parts of their life cycle in animals (malaria, for example)

8. Animal-Like Protists (Protozoa) • 5. Ciliophora • Distinguished by their cilia, for motion • Specialized structures like mouths, anal pores, contractile vacuoles (water balance)

9. Fungus-Like Protists • Resemble fungi because they form either filaments or spore-bearing bodies similar to the fungi • 1. Acrasiomycota (cellular slime molds) • Exhibit both fungus-like and animal-like characteristics during their life cycle • Spores germinate to amoebas which feed on bacteria • When food gone, they aggregate to one unit and migrate as a slug • Cells then form stalks with a spore bearing capsule on top similar to fungi

10. Fungus-Like Protists • 2. Myxomycota (plasmodial slime molds) • Grow as a single spreading mass (plasmodium) feeding on decaying veg. • When environment dessicates, stalks bearing spore capsules form • Haploid spores released from the capsule germinate into haploid amoeboid or flagellated cells, which fuse to form a diploid cell • The diploid cell grows into a spreading plasmodium

11. Fungus-Like Protists • 3. Oomycota • Water molds, downy mildews, and white rusts • Parasites or Saprobes • Form filaments (hyphae) which secrete enzymes that digest surrounding substances for absorption and digestion • Multinucleated cells • Cell walls made of cellulose, rather than the chitin found in true fungi

12. Kingdom Fungi • Grow as filaments called hyphae • A mass of hyphae is called mycelium • Some fungi have septa (cross walls), which divide the filament into compartments containing a single nucleus • When the lack septa, they are called coenocytic (multinucleated) • Cell walls consist of chitin (nitrogen-containing polysaccharide)

13. Kingdom Fungi • Either parasites or saprobes, absorbing the breakdown products from the action of digestive enzymes they secrete • Many parasitic fungi have hyphae called haustoria that penetrate their host for nutrient absorption

14. Fungi Sex • Mostly haploid, but most form temporary diploid structures for sexual reproduction… stages: • 1. Plasmogamy – fusing cells from two different fungal strains to produce a single cell with nuclei from both strains. Pair of haploid nuclei (1 from each strain) is called a dikaryon. • 2. Karyogamy – fusing of the two haploid nuclei of a dikaryon to form a single diploid nucleus. • 3. Meiosis – the diploid nucleus restores haploid condition. Daughter cells develop into haploid spores, which germinate and form haploid hyphae.

15. Fungi Asexual Reproduction • Various means: • Fragmentation: breaking up of hyphae • Budding: pinching off of small hyphal outgrowth • Asexual spores: • Sporangiospores – produced in saclike capsules called sporangia that are borne on a stalk called a sporangiophore • Conidia – formed at the tips of specialized hyphae, not enclosed inside sacs. Hyphae bearing conidia are called conidiophores

16. Fungus Groups • 1. Zygomycota • Lack septa • Reproduce sexually by fusion of hyphae from different strains • Example: Bread Mold • 2. Ascomycota • Have septa • Reproduce sexually by producing 8 haploid ascospores in a sac called an ascus • Examples: yeasts, powdery mildews, truffles

17. Fungus Groups • 3. Basidiomycota • Have septa • Reproduce sexually by producing haploid basidiospores • Fruiting body: basidiocarp (mushroom) • 4. Deuteromycota (imperfect fungi) • No sexual reproductive cycle has been observed • Example: Penicillium

18. Fungus Groups • 5. Lichens • Mutualistic associations between fungi and algae • Algae provides sugar from photosynthesis, sometimes N • Fungus provides water and protection from the environment, sometimes shield algae from UV radiation, excess light, or even toxic substances for discouraging grazers

19. Fungus Groups • 6. Mycorrhizae • Mutualistic associations between fungi and roots of plants • Plant provides sugars to the fungus • Fungus increases the ability of the roots to absorb water and minerals, especially phosphorus