Fungi cell wall strengthened by chitin - heterotrophs (decomposer, parasites, mutualists)-muticellular filaments or yeasts (single cells)

*hyphae forms a mass called mycelium- tubular cell walls surrounding the plasma membrane & cytoplasm of cells-network of tiny filaments -chitin cell wall enhance feeding by absorption -septate or coenocytic specialized hyphae1. haustoria used to extract nutrients from host2. mycorrhiza (fungus roots) improve delivery of phosphate ions and minerals to the planta. ectomycorrhiza- form sheaths of hyphae over root surface b. arbuscular mycorrhiza extend branching hyphae through root cell wall & into tubes of the root plasma membrane

*spores form new mycelia after germination - produced through sexual or asexual life cycles

A. Sexual reproduction -mycelia of different mating types release pheromones. Their hyphae fuse (process called plasmogamy: cells are in heterokaryotic stage). Then the nuclei fuse (karyogamy). Zygote is formed. -meiosis restores haploid condition -generate extensive genetic variation

B. Asexual reproduction- molds grow rapidly & produce spores-reproduction of yeasts occur by ordinary cell division

*deuteromycota- no known sexual stage

Classification of Fungi Chytrids habitat: lakes & soils globular fruiting body forms a multicellular branched hyphae

flagellated spores ex. Chytridium

Zygomycota nutrition: decomposers, parasites grow rapidly on food

coenocytic hyphae, septa found only where reproductive cells are formed

zygosporangia- metabolically inactive; heterokaryotic, then diploid ex. Mucor

Glomeromycota form arbuscular mycorrhizae with plant roots filamentous, branched hyphae

tips of hyphae that push into the root branch into tree-like arbuscules

Ascomycota (sac fungi)sexual stage: cup-shaped ascocarp (fruiting body) that contain spore-forming asci

asexual: production of spores in sac-like asci

habitat: marine, freshwater, terrestrial

nutrition: pathogenic, decomposers

life cycle: extended dikaryotic mycelium stage opportunity for genetic recombinationex. Aleuria aurantia

Basidiomycota (club fungi)nutrition: decomposers, ectomycorrhizal fungi

mushroom/basidiocarp (fruiting bodies)

Fungi are: Decomposers - cellulose & lignin in plant cell walls - responsible for keeping ecosystems stocked with inorganic nutrients essential for plant growth

Mutualists a. Fungus-Plant mutualisms

mycorrhizal fungi nitrogen-fixing fungi

endophytes (ascomycota) defense against pathogens

b. Fungus-Animal mutualisms help breakdown plant material in the gut of animals c. Lichens symbiosis between a photosynthetic microorganism & a fungus - grow on surfaces of rock, rotting logs, trees

microorganism (cyanobacteria, green algae) + fungi: ascomycete

asexual: fragmentation of parental lichen or formation of soredia (small clusters of hyphae with embedded algae)

forms: crustose, foliose, fruticose

Parasites a. Plant pathogens

Cryphonectria parasitica (ascomycota) causes chestnut blight (fungus enters cracks in the bark of chestnut trees & form hyphae inside)

Fusarium circinatum (ascomycota) cause pine pitch canker

b. Animal pathogens Claviceps purpurea (ascomycota) grows on rye plants & form ergots (purple structures); toxins in ergots [lysergic acid] cause ergotism in humans (gangrene, nervous spasms, burning sensations, hallucination, temporary insanity)

Bastrachochytrium dendrobatidis (chytrid) cause severe skin infections in amphibians

*Mycosis infection in an animal by a fungal parasite skin mycosis (i.e. ringworm)

systematic mycosis- ex. Coccidiomycosis cause tuberculosis- ex. Candida albicans cause yeast infection in vaginal lining

*Practical uses of fungi

decomposers of organic material

Saccharomyces cerevisiae yeast for bread and brew

Penicillium (ascomycota) first antibiotic; penicillin