What are Fungi? Fungi are eukaryotic heterotrophs that have cell walls made of chitin (a carbohydrate). Fungi DO NOT ingest their food, but rather they digest food OUTSIDE their bodies and the ABSORB it! (Fungi are decomposers) Reasons Fungi Not Plants! No chlorophyll Cell wall not Cellulose NO vascular tissue Do not photosynthesize (Not an autotroph)
Structure and Function Multicellular (except yeasts) Composed of hyphae—thin filaments one cell thick Cross walls—cytoplasm and nuclei can move through openings Without cross walls—contain many nuclei Structure and Function of Fungi
Structure & Function of Fungi Except for yeasts, ALL fungi are multi- cellular and composed of tiny filaments called hyphae. The bodies of multicellular fungi are composed of many hyphae tangled together into a thick mass called a mycelium. The mycelium is well suited to absorb food. The fruiting body is a reproductive structure that develops from a mycelium that grows below the surface of the ground.
Mycelium Fruiting body Hyphae Section 21-1 Fungi Structure
Reproduction in Fungi Most fungi reproduce both asexually and sexually. Asexual: In some fungi, spores are produced in structures called sporangia. Sporangia are found at the tips of specialized hyphae called sporangiophores. Sexual: Sexual reproduction involves a gametangium - a gamete-forming structure produced when the hyphae of opposing mating types of fungi meet.
How Fungi Spread How Fungi Spread Fungal spores Scatter easily in the wind Must land in favorable environment Temperature Moisture Food Some are specialized to lure animals, flies Disperse spores over long distances
21-2 Classification of Fungi Fungi are classified according to their structure and method of reproduction The 4 main groups of fungi are: 1. Zygomycota (common molds) 2. Ascomycota (sac fungi) 3. Basidiomycota (club fungi) 4. Deuteromycota (imperfect fungi)
Zygomycota – The Common Molds Zygomycetes are the familiar molds that grown on meat, cheese, and bread. Ex: Rhizopus stolonifer (black bread mold). the rootlike hyphae that anchor the fungus to the bread are called rhizoids the stem-like hyphae that run along the surface of the bread are called stolons
FERTILIZATION Diploid Haploid MEIOSIS Sexual Reproduction Asexual Reproduction Zygospore (2N) Spores (N) Sporangium Zygospore (2N) + Mating type (N) Stolons Rhizoids - Mating type (N) Spores (N) Sporangiophore Sporangium Gametangia Section 21-2 p. 531 Figure 21-5 The Life Cycle of Rhizopus
Ascomycota – The Sac Fungi The phylum Ascomycota is named for the ascus, a reproductive structure that contains spores. Ascomycetes are the largest phyum in the kingdom Fungi. Some are large and some are microscopic. Examples: cup fungi (large) and yeasts (microscopic).
FERTILIZATION MEIOSIS HYPHAE FUSE Diploid Haploid Sexual Reproduction Asexual Reproduction Section 21-2 p. 533 Figure 21-7 The Life Cycle of an Ascomycete Hypha (N) Conidiophore Conidia (N) + Mating type (N) - Mating type (N) 8 Ascospores (N) Ascus Zygote (2N) Ascus (N + N) Fruiting body (N + N) Hyphae (N + N) Gametangia Asci Hyphae (N)
Yeasts Unicellular fungi Ascomycetes—baking and brewing Budding—process of asexual reproduction—cell division Alcoholic fermentation to obtain energy Byproducts—carbon dioxide and alcohol Yeast is an Ascomycete Fungus
Sac Fungi - Ascomycota CUP FUNGI (visible to the eye) YEASTS (microscopic)
Basidiomycota – The Club Fungi The phylum Basidiomycota gets its name from a specialized reproductive structure (called a basidium) that resembles a club. Includes: Mushrooms Shelf fungi Puffballs Earthstars Jelly fungi Plant rusts Bird’s nest fungi
FERTILIZATION MEIOSIS HYPHAE FUSE Fruiting body (N + N) Button Secondary mycelium (N + N) Primary mycelium (N) + Mating type (N) - Mating type (N) Basidiospores (N) Zygote (2N) Basidia (N + N) Gills lined with basidia Gills Stalk Base Cap Haploid Diploid Section 21-2 p. 534 Figure 21-8 The Life Cycle of a Basidiomycete
Mushrooms – “Club Like” Fungi or Basidiomycete Fungi
The Club Fungi Diversity of Club Fungi Mushrooms Shelf fungi Puffballs Earthstars Jelly fungi Rusts Edible and Inedible Mushrooms Almost identical Some inedible can cause severe illness or death
Diversity of Club Fungi EARTH STAR JELLY FUNGI MUSHROOM BIRD’S NEST FUNGI PUFFBALL SHELF FUNGI
Deuteromycota – The Imperfect Fungi Deuteromycota is an extremely varied phylum composed of those fungi that are not placed in other phyla. The term imperfect implies that these fungi do not appear to have sexual reproduction. Ex: Penicillium notatum – the source of antibiotic penicillin.
-Regarded as imperfect because they exhibit no sexual stage has been observed in their life cycle -Members are not closely related and are not necessarily similar in structure or appearance; do not share a common ancestry, polyphyletic = coming from many ancestors – hmm weird Deuteromycota (Imperfect Fungi)
Truffles are round, warty, fungi that are irregular in shape. They vary from the size of a walnut to that of a man's fist. Since the times of the Greeks and Romans these fungi have been used in Europe as delicacies, as aphrodisiacs, and as medicines. They are among the most expensive of the world's natural foods, often commanding as much as $250 to $450 per pound. Truffles are harvested in Europe with the aid of female pigs or truffle dogs, which are able to detect the strong smell of mature truffles underneath the surface of the ground. The female pig becomes excited when she sniffs a chemical that is similar to the male swine sex attractant. The use of dogs to find truffles is also and option.
21-3 Ecology of Fungi All Fungi Are Heterotrophs Saprobes - Organisms that obtain food from decaying organic matter Parasites - which harm other orgnisms Symbionts - live in close and mutually beneficial association with other species Capture live animals Pleurotus ostreatus Lives on the sides of trees and trap worms to digest them
Fungi as Decomposers Maintain equilibrium in nearly every ecosystem by recycling nutrients Release digestive enzymes that break down organic material into simple molecules which diffuse into the fungus 21-3 Ecology of Fungi
Fungi as Parasites Cause serious plant and animal diseases and a few cause diseases in humans Plant Diseases Smuts, mildews, rusts Corn smut Plant mildew Spruce rust 21-3 Ecology of Fungi
Parasitic fungi cause serious plant and animal diseases: wheat rust mildew on fruit 21-3 Ecology of Fungi
Other Basidiomycetes Rusts and Smuts Rust infecting wheat leaves Rust infecting a Leaf Whitrot Smut digesting old wood
Human Diseases Athlete’s foot, ringworm Candida albicans (yeast)—oral thrush Bacteria and yeast in the human body keep each other in check 21-3 Ecology of Fungi
Other Animal Diseases Cordyceps— grasshoppers in rain forests in Costa Rica 21-3 Ecology of Fungi
Symbiotic Relationships Mutualistic (both benefit) Lichens Fungus and an alga or a cyanobacterium or both Live mostly on bare rock and in places that most other organisms cannot live Break down rock into soil Autotroph makes food, fungus absorbs water and nutrients and serves as an anchor 21-3 Ecology of Fungi
Lichens are mutualistic symbiotic organisms. They have an ____________ fungus and a _________ or cyanobacterial portion. There are three lichen growth forms which are predominant in nature: _____________________ _____________________________
Symbiotic Relationships Lichens A symbiotic associations between a fungus and a photosynthetic organism. Lichen can grow on dry, bare rock and are often the first organisms to inhabit an area (pioneer species). The lichen break down the bare rock, allowing other plants to grow. lichen
Symbiotic Relationships mycorrhizae Mycorrhizae A symbiotic associations of plant roots and fungi. Fungi increases the surface area of the plants roots. Its presence is often necessary for the growth of many plants.
Mycorrhizae Plant roots and fungi Plant roots provide energy and fungus provides a large surface area for more absorption of water and minerals 21-3 Ecology of Fungi
PhylumEx’sCharacteristicsAsexualSexual ZygomycotaBread Mold Rhizopus a dung fungus Chitin cell walls Coenocytic = hyphae lack crosswalls Unflagel. spores drop from sporangia Gametangia fuse to create zygospore AscomycotaYeast, morels, truffles Conidia on conidophores Hyphae + & - fuse to create ascospores in ascus BasidiomycotaMushrooms Puffballs, rusts, smuts Cross walls in hyphae Asexual by way of Conidophores which produce conidiospore s Sexual when hyphae fuse in BASIDIA to produce basidiospores Fungi Imperfecti Deuteromycota Penicillium, Athlete’s Foot fungus, Tomato Blight Similar To Basidio and Zygomy Asexual by conidia which produce conidophores Sexual repro Not known