210 likes | 346 Vues
Kingdom Fungi. General Characteristics. All fungi are eukaryotes (nucleus and other organelles). Most fungi are multicellular , but some, like yeasts, are unicellular. Fungi are heterotrophic, but they cannot ingest their food because their cell walls are too thick. General Characteristics.
E N D
General Characteristics • All fungi are eukaryotes (nucleus and other organelles). • Most fungi are multicellular, but some, like yeasts, are unicellular. • Fungi are heterotrophic, but they cannot ingest their food because their cell walls are too thick.
General Characteristics • Fungi absorb nutrients into their cells by releasing enzymes that break down nutrients before they are taken in. • Fungi have cell walls (like plants) but do not contain chloroplasts.
Heterotrophic Fungi • Saprophytes • Live off dead/dying plants and/or animals. • i.e. mushrooms • Parasites • Live directly off a host. • i.e. athlete’s foot • Symbionts • Live in a close relationship with other organisms. • i.e. lichen
Kingdom Fungi • We will be studying 5 phyla in kingdom fungi: • Oomycota (p. 409) • Zygomycota (p. 410) • Ascomycota (p. 411) • Basidiomycota (p. 414) • Deuteromycota (p. 415) • Mycota = mykos (Greek for mushroom)
Structure of a Typical Fungus • The body of a typical fungus is composed of masses of tangled filaments called hyphae (singular = hypha).
Structure of a Typical Fungus • The entire mass of tangled filaments if collectively called the mycelium. • The mycelium increases that surface area so that more fungus can come into contact with the food (like bread).
Cross Walls • One way to tell one fungus from another is by the presence or absence of cross walls. • Each cell may have 1 or more nuclei. • The cross walls are made of cellulose or chitin. Both of these are carbohydrates.
Reproduction of Fungi • Most fungi can either reproduce asexually (1 parent) or sexually through the use of mating types + and -.
Life Cycle of the Black Bread Mold • Label the diagram: • A: spores • B: sporangium • C: sporangiophore • D: sporangium • E: spores • F: stolons • G: zygosporangium • H: zygospore • I: rhizoids • J: gametangia
Life Cycle of the Black Bread Mold • Asexual reproduction: • Step 1: Sporangia produce (N) spores (up to 40,000 per sporangium!) • Step 2: Sporangia open when mature and release (N) spores to wind, water and gravity. • Step 3: Spores germinate when temperature and moisture allow them to. • Step 4: New masses of hyphae form which grow into mycelia.
Life Cycle of the Black Bread Mold • Sexual reproduction: • Step 1: Mating types + and – fuse together. • Step 2: Gametangia are formed which produce (N) gametes. • Step 3: Gametes fuse together to form a (2N) zygosporangium. A thick wall forms around it to produce a (2N) zygospore.
Life Cycle of the Black Bread Mold • Sexual reproduction: • Step 4: The zygospore may remain dormant. Later it undergoes meiosis and grows a hypha. • Step 5: Hypha grows a sporangium which produces (N) spores. • Step 6: Spores can germinate and grow hyphae/ mycelia. • ** Alternation of generations. The 2N portion of the life cycle if only during the zygospore period. **