Chapter 19 part II Fungi

General characteristics Variety of moist habitats Variety of sizes and colors Variety of temperatures All decompose large amounts of organic waste materials

Fungal structure Hyphae Develop from spores Branch to form a network of mycelium Divided by cross walls (septa) Cytoplasm passes through pores in septa to allow transport of nutrients Some hyphae have no septa

Fungal structure Cell walls Made of chitin (carbohydrate)

Food getting Extracellular digestion Food is digested outside of fungus cells Hyphae release enzymes to digest food and nutrients released are absorbed (pass into cells by diffusion or facilitated diffusion)

Food getting Feeding relationships of fungi and plants Fungi absorb nutrients from plants but provide the plant with water and minerals Some fungi parasitize plants and animals (athlete’s foot, yeast infections, tree fungus) Some fungi are decomposers and use dead organic materials for nutrients

Reproduction is asexual Fragmentation Pieces of hyphae break off and grow new mycelia Budding Mitosis occurs producing new individual fungi which separates from the parent cell Spores Reproductive cells made that germinate and develop into new organisms

Classification Fungi are classified by spores produced in sexual reproduction or meiosis

Adaptations Spores Small and light weight for easy dispersal Produced in large quantities Can be dispersed by wind, water, animals, insects

Phyla of fungi Zygomycota-Zygospore forming Ascomycota-Sac forming Basidiomycota-Mushroom forming Deuteromycota-no sexual reproduction Mutualistic Mycorrhiza-fungi and plants Lichens-fungi and algae or cyanobacterium

Zygomycota Form zygospores Decomposers Reproduce asexually w/ spores Hyphae grow upwards and release spores Reproduce sexually w/ thick-walled spores Triggered by environmental change 2 hyphae come in contact and fuse to form haploid gametangia Gametangia fuse to form zygote that develops into zygospore

Zygomycota continued Growth Stolons are hyphae that grow horizontally on the surface of a food source Rhizoids penetrate the food to anchor mycelium and are the site of extracellular digestions and nutrient absorption

Ascomycota Sac fungi are largest group w/30,000 species Produce asci (sacs) that contain sexual spores (ascospores) Asexual reproduction Hyphae rise up from mycelium to produce asexual spores Spores are dispersed by wind, water, animals

Ascomycota continued Importance Decompose food products Cause plant diseases Apple scab, Dutch elm, ergot Some attack people and animals Some are edible Morels Truffles Yeasts (food and research)

Basidiomycota Club fungi include mushrooms, puffballs, stinkhorns, bracket fungi, smuts, rusts Basidia (club shaped hyphae) produce spores Mushroom (stalk and cap) produce sexual spores for a short period of time (p. 570)

Deuteromycota NO known sexual reproduction One type produces penicillin Some used in soy sauce and cheese Some used to produce citric acid

Mutualism Mycorrhiza: fungus and plant roots Fungus increases amount of nutrients absorbed by the plant: P, Cu, other minerals Fungus keeps soil damp around plant roots Plant gives fungus organic nutrients like sugar and amino acids 80-90% of all plants have mycorrhiza

Mutualism continued Lichens-fungus with a green alga or cyanobacterium Fungus provides habitat and retains moisture, gives minerals to alga and protects from sunlight Alga photosynthesizes and gives fungus food Only need light, air and minerals Found in every environment

Lichens

Lichens