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Fungi. Chapter 26. Characteristics. Fungi are eukaryotic, heterotrophic and most are multicellular, but some can have unicellular stages Yeast cells are unicelluar and the fungus best known for making bread rise; mushrooms, mold and mildew are also fungi
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Fungi Chapter 26
Characteristics • Fungi are eukaryotic, heterotrophic and most are multicellular, but some can have unicellular stages • Yeast cells are unicelluar and the fungus best known for making bread rise; mushrooms, mold and mildew are also fungi • The study of fungi is called mycology • There are three main phyla of fungi: Zygomycota, Ascomycota and Basidiomycota
Nutrients • Fungi get their nutrients by absorbing organic molecules from the environment • Instead of ingesting food and digesting the nutrients inside of the cells, fungi secrete digestive enzymes out of their cells and absorb the digested nutrients into their cell walls • Some fungi are saprophytic, meaning they get their organic nutrients from dead materials
Structure • Fungi have filaments called hyphae and cell walls that contain chitin • Chitin is a polysaccharide that also makes up the exoskeletons of insects, crustaceans and other arthropods • Multiple hyphae that form the body of a fungus are called mycelium • Some species have hyphae that are divided, but some species do not
Reproduction • Fungi can reproduce both asexually and sexually • Asexual Reproduction: • Produce identical haploid spores • Different types of fungi produce different types of spores:sporangiosporesor conidiophores • These spores are different due to whether they have divisions in their mycelia or not
Sexual Reproduction • Many, but NOT ALL, species can reproduce sexually, creating genetic variation • Fungi are neither male nor female; instead we say that fungi are either plus or minus • Only + and – can mate with each other, NOT + and + or – and – • In sexual reproduction, the hyphae of a + wil fuse with the hyphae of a – and their nuclei will combine their genetic information
Zygomycota • Most of these are terrestrial and found in soil • Mycelia of zygomycetes are not divided (coenocytic) • Bread mold is included in this phylum • Zygomycetes can reproduce both asexually and sexually • Sexual spore of zygomycetes is called a gametangium (2n)
Basidiomycota • Often called club fungi because of their clublike sexual reproductive structures (basidia) • The basidiocarp are the structures like mushrooms that have spores in their gills • Most members of basidiomycota are mushrooms, but not all of them
Ascomycota • These are known as sac fungi because of their sexually reproducing forms • Some members of this phyla are called cup fungi because of the structures that hold the sacs of spores (asci) • Many yeast species are ascomycetes • These are fungi that help bread rise and ferment grapes into wine
Mycorrhizae & Lichens • Mycorrhizae have a symbiotic relationship with plant roots • Found on more than 80% of vascular plants • Helps the plant take up nitrogen, phosphates and other ions • All three fungal phyla can form mycorrhizae • Lichens have a symbiotic relationship with a photosynthetic partner (usually green algae) • Most of these are ascomycota • The fungi provide shelter, while the photosynthesizer provides sugars
Fungi and Humans • Fungi can interact with humans by causing disease, they are used in industry and we eat them occasionally • Each phyla can contribute to disease and industry • Food fungi mostly come from Basidiomycota (mushrooms)
Diseases • Common fungal infections: • Ringworm • Athlete’s foot • Candida albicans • Other fungal infections • Histoplasmacapsulatum, Paracoccidioidesimmitis, and Blastomycesdermatitidis • All of these cause respiratory illnesses and can be inhaled from soil and bird feces
Industry • Fungi can be used in nonfood industries, such as pharmaceuticals and genetic engineering • The antibiotic penicillin is created from the fungi in the genus Penicillium • Cortisone cream is made from chemicals from the genus Rhizopus • Saccharomyces cerevisiae has been vital in genetic engineering: vaccine for Hep B and production of ethanol for automobile fuel
Food • Many species of fungi either aid in the production of food or are food themselves • Yeast (S. cerevisiae) is an important nutritional supplement because it contains vitamins, minerals and other nutrients • Many mushrooms species are found in grocery stores for consumption • Some fungi can damage foods: bread and fruit mold in the kitchen, corn and wheat smut in fields