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Lecture on fungi [11 25-13 monday]
 

Lecture on fungi [11 25-13 monday]

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  • (Know for lab exam)
  • Mycelia: networks of branched hyphae (cells)the mass of interwoven filamentous hyphae that forms especially the vegetative portion of the thallus of a fungus and is often submerged in another body Septum (cell wall) separating the hyphaea dividing wall or membrane especially between bodily spaces or masses of soft tissue compare dissepimentCoenocyte fungi lack septa and cellular contents can flow between the hyphaemultinucleate mass of protoplasm resulting from repeated nuclear division unaccompanied by cell fission  
  • a structure within which spores are produced
  • Lab exam
  • hytrids are unique among fungi in having a flagellated stage. They produce zoospores with a single flagellum, making them capable of active movement through water.Chytrids produce zoospores with a single flagellum, making them capable of active movement through water. Because of this, early taxonomists classified them as protists. According to rRNA sequences in ribosomes, the chytrids are the most primitive of the fungal phyla.zoosporean asexual spore of some algae and fungi
  • The life cycle of Rhizopusstolonifer is representative of zygomycete species. This cycle begins with the penetration of food surface by coenocytic hyphae in order to absorb nutrients. Septa are only found where reproductive cells are made.In the asexual phase, haploid spores form and develop in the sporangium (black bulbs at the tip of hyphae), are dispersed in the air, and land on food to germinate.During times of nutrient deficiencies, some mold can reproduce sexually. Different chemical markers are used for mating recognition between variable mycelia types. A zygosporangium is formed, which is the site of karyogamy and meiosis.The zygosporangium contains heterokaryotic cells with haploid nuclei; diploid nuclei follow karyogamy. When favorable conditions are restored, meiosis proceeds and diverse haploid spores are released.TermszygosporangiumA sporangium that produces a single zygospore. zygomycetean organism of the phylum Zygomycotacoenocytica multinucleate cell that can result from multiple nuclear divisions without their accompanying cytokinesisExamplesThe hyphae of zygomycetes spreading across leaf litter (Figure 1) is a component of the decomposition process. The species is Pliobolus, and it can aim the sporangia toward light.
  • Glomeromycetes are extremely important ecologically, forming nearly all arbuscular mycorrhizae, a critical association with plants.
  • Ascomycetes are the largest known group of fungi, occur in various ecosystems, and are very important ecologically, nutritionally, and medically.Asci are sac-like structures that contain spores and are present during sexual reproduction. Ascocarps are reproductive fruiting bodies that can be micro- or macroscopic.Conidia are asexual spores and are produced by conidiophores at the top of hyphae where they are dispersed into the air for distribution.Conidia can fuse with compatible mycelium to participate in sexual reproduction that includes plasmogamy and the formation of cells with haploid nuclei from each parent. Asci then develop at the hyphae tips resulting in four genetically diverse nuclei and ultimately eight ascospores.conidiaasexual, non-motile spores of a fungus and are named after the Greek word for dust, conia and are also know as conidiospores and mitosporesascocarpthe sporocarp of an ascomycete, typically bowl-shapedascomyceteany fungus of the phylum Ascomycota, characterized by the production of a sac, or ascus, which contains non-motile spores
  • Basidiomycetes: typical mushroom
  • Key PointsThe basidiomycetes (phylum Basidiomycota) are comprised of roughly 30,000 species that include mushrooms, shelf fungi and puffballs.The basidium is a specific, club-shaped cell where karyogmay is carried out followed by meiosis. This gives rise to the name club fungus.A diploid nucleus is formed during karyogamy and then undergoes meiosis, resulting in four haploid nuclei. The basidium divides into four arms, with a single haploid nucleus in each that will develop into a basidiospore.The reproductive cycle of basidiomycetes has a long dikaryotic mycelium stage allowing for genetic diversity as a result of recombination.Basidiomycetes are particularly important in nature as decomposers of plant material, especially dead wood and trees.Termsbasidiuma small structure, shaped like a club, found in the Basidiomycota phylum of fungi, that bears four spores at the tips of small projectionsKaryogamyThe fusion of two nuclei within a cell.MyceliumThe vegetative part of any fungus, consisting of a mass of branching, threadlike hyphae, often underground.myceliumthe vegetative part of any fungus, consisting of a mass of branching, threadlike hyphae, often underground

Lecture on fungi [11 25-13 monday] Lecture on fungi [11 25-13 monday] Presentation Transcript

  • Lecture on Fungi 11/25/13 Monday
  • Characteristics • • • • nonphotosynthetic Most are saprobes (feed on dead things) Cell wall made of chitin Genetically more similar to animals
  • Importance • • • • Decomposer and recycler of nutrients Consumed as food and food production Truffles, morels, mushroom Antibiotic: penicillin
  • Antibiotics • Cyclosporin prevent organ rejection • Statin lowers cholesterol • Penicillin
  • Mutual symbionts of pants • Mycorrhizae • lichens
  • lichen • Mutual symbiont of algae • Indicator of air pollution • Source of dyes (litmus)
  • Three forms of lichen (Know for lab exam) 1. Crustose: crustlike, growing tight against the substrate. 2. Foliose: leaflike, with flat sheets of tissue not tightly bound 3. Fruticose: free-standing branching tubes.
  • Mycoses • Agents of disease
  • Four Fungal diseases 1. 2. 3. 4. Thrush: yeast infection Histoplasmosis : lung infection Aspergillosis : mold in your house Cryptococcus /Valley fever: can lead to pneumonia and meningitis
  • ergotism • Clavicles fungus • Salem witch trials
  • Sporotrichosis: rose gardener’s disease • Fungal antibiotics are harmful; humans and fungi are eukaryotes. Bacterial infections are better to treat because they are prokaryotes
  • Tinea Infections (Ringworm) • Infection on skin and nail’s keratin
  • Claviceps purpurea, cause of ergotism
  • Plant diseases caused by fungi 1. Rust 2. Apple Scab 3. smut
  • cellular • Unicellular (yeast) • Multicellular (mold) • Some are yeast inside and mold outside the body
  • Structure • Mycelia: networks of branched hyphae (cells) • Septum (cell wall) separating the hyphae • Coenocyte fungi lack septa and cellular contents can flow between the hyphae
  • Septate hyphae • Septum: a cross-wall formed in association with the mitotic division of a cell, laid down between the cells, usually at regular intervals.
  • Coenocytic hyphae • multinucleate mass of protoplasm resulting from repeated nuclear division unaccompanied by cell fission
  • Types of mycorrhizae fungi • Ecto : grow into the extracellular species of the root cortex (truffle) • Endo: grow into the root cell (orchid)
  • Reproduction • Plasmogamy: union of two parent mycelia • Heterokaryon: cell or mycelium in some fungi that do not result in the fusion of two nuclei • Dikaryotic: the nucleus pair off two to a cell
  • Karyogamy (nuclear fusion) • Produce diploid cells • Takes a long time • 2n phase is short-lived and undergo meiosis, producing 1n spores
  • sporangium • Fungal structures where asexual spores are produced • exam
  • budding • Simple cell division in which yeast repouce asexually
  • Imperfect fungi/deuteromycetes • Some fungi have no known sexual stage
  • Evolution • Fungi descended from protists • Fungi and Animalia are sister kingdoms
  • Groups you must know 1. 2. 3. 4. 5. Chytridiomycota: earliest fungi Zygomycota Glomeromycota Ascomycota Basidiomycota
  • Chytridiomycota: earliest fungi • • • • Found in water Saprobic or parasitic B. dendrobatids: decline of frog population Chytrids diverged earliest
  • Zoospores: flagellated spores • Only chytrids have zoospores
  • Zygomycota • • • • Asexual and sexual spores Zagospore (sexual) Sponragiospores (asexual spores) Very cold/heat tolerant, responsible for food spoilage • Black bread mold Rhizopustoloniser • pilobolus
  • Life cycle • Zygomycota
  • glomeromycota • Arbuscular mycorrhizae: endo • 80% of all vascular plants have arbuscular mycorrhize • Reproduce asexually • Help plants absorb phosphorous and help a crucial role in colonization of land by plants
  • Ascomycetes (cup fungi) • Asci: sexual spores that are found in saclike structure • Reproduce sexually • Many asci are found on the fruiting body called ascocarp • Ex. Truffle • Conodia: asexual spores • Conodiophore: structure
  • Penicillium conidiophores
  • Sporangium conidiophore
  • Aspergillus condiophore
  • Ascomycetes • Truffles, yeast, penicillin, morels
  • Ascomycetes • Fungal partner in lichen is an ascomycete
  • Basidiomycetes: typical mushroom • Basidium: structure where sexual spores (basidiospores) are produced • Gills with basidia
  • Reproduction of Basidiomycetes: typical mushroom • Sexual mostly resulting in dikaryotic fruiting bodies called basidiocarps (mushroom) • Karygomy occurs in the gills of the mushroom cap where basidium and basidiophores are found • Asexual reproduction is rare and occur via fragmentation • Ex. Club fungi, rust, smut, puff balls, shelf fungi, mushrooms
  • Basidiomycete life cycle • • • • • • • • • • • • Basidiomycetes – Fungi Key Points The basidiomycetes (phylum Basidiomycota) are comprised of roughly 30,000 species that include mushrooms, shelf fungi and puffballs. The basidium is a specific, club-shaped cell where karyogmay is carried out followed by meiosis. This gives rise to the name club fungus. A diploid nucleus is formed during karyogamy and then undergoes meiosis, resulting in four haploid nuclei. The basidium divides into four arms, with a single haploid nucleus in each that will develop into a basidiospore. The reproductive cycle of basidiomycetes has a long dikaryotic mycelium stage allowing for genetic diversity as a result of recombination. Basidiomycetes are particularly important in nature as decomposers of plant material, especially dead wood and trees. Terms basidium a small structure, shaped like a club, found in the Basidiomycota phylum of fungi, that bears four spores at the tips of small projections Karyogamy The fusion of two nuclei within a cell. Mycelium The vegetative part of any fungus, consisting of a mass of branching, threadlike hyphae, often underground. mycelium the vegetative part of any fungus, consisting of a mass of branching, threadlike hyphae, often underground
  • Glossary • http://bugs.bio.usyd.edu.au/learning/resourc es/Mycology/Glossary/glossary_a_b.shtml