7.4 Fungi

1. 7.4 Fungi • Key concepts: what characteristics do fungi share? • How do fungi reproduce? • What roles do fungi play in nature? • Key terms: • Fungi • Hyphae • Fruiting body • Budding • Lichen

2. What are fungi? Fungi: eukaryotes that have cell walls, are heterotrophs that feed by absorbing their food, and use spores to reproduce Usually need moist warm places

3. Cell stucture • Fungi range in size from tiny unicellular yeasts to large mushroom things • Most are arranged in structures called hyphae – branching, threadlike tubes that make up the multicellular bodies • Hyphae of some fungi are continuous threads of cytoplasm that contain many nuclei • What a fungus looks like depends on how its hyphae are arranged

4. Obtaining food • Fungi absorb food through hyphae that grow into a food source • First, the fungus grows hyphae into the food source • Then, digestive chemicals ooze into the food • The chemicals break down the food and it is absorbed

5. Reproduction • Fungi usually reproduce by making spores. The lightweight spores are surrounded by a protective covering and can be carried easily through air or water to new sites • Fungi produce spores in reproductive structures called fruiting bodies – varies among different fungi

6. Asexual reproduction • Most fungi reproduce both asexually and sexually. (….what…???) • WHEN there is adequate moisture and food, they reproduce asexually. Cells at the tips of the hyphae divide to form spores • Unicellular yeasts undergo budding – no spores are produced, instead a small yeast cell grows from the body of the parent and then breaks away and lives on its own

7. Sexual reproduction • Most fungi can reproduce sexually • Hyphae of the two fungi grow together and genetic material is exchanged. Eventually, a new structure grows from the joined hyphae and produces spores. The spores develop into fungi that differ genetically from either parent.

8. Classification of fungi • Three major groups • Club – produce spores in tiny clublike structures (mushrooms, rusts, puffballs) • Sac – produce spores that look like sacs (yeasts, morels, truffles) • Zygote – produce resistant spores (fruit and bread molds)

9. Fungi roles • Provide foods, decompose, recycle • Some cause disease, some fight disease • Foods – yeasts, molds, mushrooms

10. More roles • Decomposers • Disease fighters – penicillin • Disease causers – athlete’s foot • Fungus-plant root • Help plants grow larger by growing on or into plants’ roots • Lichens – fungus and algae or autotrophic bacteria that live together in mutualism. Often called “pioneer” organisms because they are the first to appear on bare rocks in an area.