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Fungi - Overview  True multicellularity with differentiation  Strict heterotrophs  Release enzymes into environment- digestion is extracellular  Most are saprophytic  Along with bacteria, fungi are important as decomposers

Fungi- Structure  Multi-cellular but there are no divisions between the cells  Have multiple nuclei and continuous cytoplasm  Branched tubes are called hyphae  Increased surface area allows for absorption  Masses of tubes are called mycelium

Fungi - Structure cont’d  Fungal mycelia and hyphae  Fig

28-5 Fungi – Structure cont’d.  Cell structure  Cell walls contain chitin  Polymer of glucose  Each glucose has an amino group attached  Found in exoskeletons of animals  Haploid is most prominent phase  Energy stored as glycogen  like animal cells  Move toward food source by growing toward it  Hyphae can grow as much as a meter per day!

Fungi - Reproduction  Adapted to dry land-produce wind-blown spores  Can reproduce asexually or sexually  Method of reproduction used to classify  Asexually  Fragmentation  part of the mycelium breaks away from its parent  each broken fragment gives rise to a new mycelium.  Spore release  Haploid reproductive cell  germinates and develops into new mycelium

28-7 Fungi – Reproduction cont’d  Sexual reproduction (generally)  Conjugation of two different mycelia  Designated as + and –  Dikaryonic state-in some, the + and – nuclei do not fuse for long periods of time  After fusion of nuclei a zygote forms- undergoes meiosis  Produces haploid spores and cycle begins again

Fungi – Reproduction cont’d  Dispersal of spores  Fig

28-9 Phlyum Zygomycota  Zygospore fungi  Saprotrophs and parasites  Rhizopus stolonifer  black bread mold  Characteristic Reproduction  formation of a zygospore from fusion of +/- hyphae

Phlyum Zygomycota  Black bread mold Rhizopus stolonifer  Fig

28-11 Phylum Ascomycota  Sac fungi  diverse group includes yeast, powdery mildew, penicillin, and truffles!  Characteristic Reproduction  Asexual  Produce conidia spores.  Sexual  Ascocarp (Fruiting body) develops after fusion of +/- hypae  Fusion of +/- nuclei forms sexual reproductive structure called an ascus (pl. asci)  Ascus produces spores by meiosis

Phylum Ascomycota cont’d  Unicellular ascomycetes are often called yeasts  Unequal binary fission- called budding  Fermentation by some yeasts produces CO2 and ethanol  Used to make beer, wine, and bread 28-12

Phylum Ascomycota cont’d  Asexual reproduction in sac fungi  Fig

Phylum Ascomycota cont’d  Sexual Reproduction  Fig

Phylum Basidiomycota  Club fungi  Most mushrooms  Characteristic reproduction  Sexual reproduction is most prominent in this group  Elaborate fruiting bodies, called basidiocarps  Contain cells called basidia (sing. Basidium) which produce four sexual spores

Phylum Basidiomycota cont’d  Fig  Sexual reproduction in club fungi

28-17 Phylum Deuteromycota  Imperfect fungi  Includes many familiar fungi  Aspergillis- used to make soy sauce from fermenting soy beans  Penicillium- original source of penicillin  Penicillium roquefortii and camemberti- used in making blue cheeses  Deuteromycetes always reproduce asexually  Produce conidia on aerial hyphae  Sexual stage has not been identified and may not exist

28-18 Blue cheese  Fig

28-19 Fungi cont’d.  Environmental importance of fungi  Fungi and photosynthesizers  Lichens- associations between fungi and cyanobacteria or green algae  Efficient at acquiring nutrients and moisture-can colonize poor soil, rocky surfaces  Produce organic matter and create new soil  3 characteristic forms- crustose, foliose, fruticose  Body of lichen has 3 layers-fungi form top and bottom layers and protect middle layer of photosynthetic cells  Protects photosynthesizer and delivers water  Photosynthesized gives the fungus nutrients

28-20 Lichen morphology  Fig

28-21 Fungi cont’d.  Environmental aspects, cont’d.  Mycorrhizal fungi  Mutualistic relationships with plant roots  Helps plants to grow more successfully in poor soils  Fungi can live on the outside surface of roots, or it can penetrate the root tissues  Plant provides organic nutrients to the fungus  Fungus brings water and minerals to the plant  Hyphae provide lots of surface area for water absorption

28-22 Fungi cont’d.  Medical aspects of fungi  Fungal diseases of plants  Many enter through the stomata of the leaves or through a wound  Smuts and rusts- sac fungi that parasitize cereal crops  Fungal diseases of humans  Mycoses  Cutaneous- affect only the skin  Subcutaneous-deeper skin layers  Systemic-spread throughout the body  Many fungal diseases are acquired from the environment  Ringworm from soil fungi for example

28-23 Smuts and rusts  Fig

28-24 Fungi cont’d.  Human fungal diseases  Tineas  Skin infections-can occur anywhere on the skin  Athlete’s foot- scaling, peeling, and itching between toes  Ringworm- redness and inflammation due to enzymes released by the fungus; extends outward in a ring-shape  Histoplasmosis  Caused by Histoplasmosis capsulatum; common in the Midwest  Carried in bird droppings  Mild flu-like symptoms, fungus lives in cells of the immune system  Healed lesions in the lungs calcify  Candidiasis  Yeast infections resulting from imbalance of normal flora

28-25 Human diseases caused by fungi  Fig

28-26 Fungi cont’d.  Control of fungi  Fungi more closely resemble animal cells than bacteria  Makes it harder to develop antibiotics that will kill fungi and not the host  Fungi synthesize steroids differently- fungicides are directed at steroid biosynthesis

Sexual Reproduction  Mycelium grows below the surface  When two hyphae meet they fuse and begin to swell until they break through the soil surface and form spherical buttons  As the buttons mature they form a stalk and cap  Nuclei from each fungi fuse

Sexual Reproduction (cont’d)  Fused nuclei form spores  Spores are made of:  Dehydrated cytoplasm  Protective coat  Wind, animals, water, & insects spread spores  Over 2 billion spores can be produced from one field mushroom  When the spores land in a favorable place their protective coat splits and they germinate  Through mitosis new hyphae will produce a new fungus

Importance of Fungi  Decomposition  Produces much of the raw materials that plants need for growth  Yeast  Used to make bread, wine, and beer  Food  Mushrooms, morels, and truffles are used in cooking

Importance of Fungi  Medicine  E.g. penicillin  Breaking down pollutants  Symbiotic relationships with some plants  Help plants absorb nutrients in exchange for sugars

Human Diseases/Conditions caused by Fungi  Ringworm  Skin infection  spreads quickly by direct or indirect contact  Athlete’s foot  Usually contracted from contaminated shower floors

Human Diseases/Conditions caused by Fungi  Poisoning  Many mushrooms are toxic and can cause sickness and death  Hallucinations  Some mushrooms contain psilocybin which is structurally similar to LSD and mescaline