Chapter 21: Protists and Fungi

1. Chapter 21: Protists and Fungi Section 21-4: Fungi

2. What are Fungi? • Heterotrophs – produce enzymes that digest food outside their bodies, then absorb the nutrients • Most feed on decaying material in the soil, some are parasitic • Cells walls made of chitin – also found in exoskeletons of insects • More closely related to animals than plants

3. Structure and Function • Yeasts are the only unicellular fungi • Mushrooms and other fungi are larger, with bodies made up of cells forming long, slender branching filaments called hyphae

4. Structure and Function • Cross walls divide the hyphae into compartments, each containing 1 or 2 nuclei • Openings in cross walls allow cytoplasm and organelles to move • Body of mushroom called fruiting body – reproductive structure of a fungus • Grows from mycelium – mass of branching hyphae below soil • Clusters of mushrooms can have same mycelium

6. Reproduction • Reproduce asexually, primarily by releasing spores adapted to travel through air or water • Breaking off hypha or budding also

7. Reproduction • Most reproduce sexually - life cycle of the bread mold Rhizopus stolonifer

8. Sexual Reproduction • 2 mating types - + and 1 • Genetic and fossil evidence shows eukaryotes evolved from prokaryotes, more closely related to Archae than Bacteria • Split may have come as early as 2.5 bya • Protist group now includes as many as 300,000 species • Most remained unicellular – except those leading to plants, animals, and fungi