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

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

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

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

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

Reproduction O Most reproduce sexually - life cycle of the bread mold Rhizopus stolonifer

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