Classification II Protista & Fungi AP Biology

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

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

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?

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

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

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)

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

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

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

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

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)

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

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.

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

Fungus Groups 1. Zygomycota 2. Ascomycota 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

Fungus Groups 3. Basidiomycota 4. Deuteromycota (imperfect fungi) 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

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

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