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

Chapter 21: Protists and

FungiSection 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 FunctionO Yeasts are the only unicellular fungiO Mushrooms and other fungi are

larger, with bodies made up of cells forming long, slender branching filaments called hyphae

Structure and FunctionO 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 fungusO Grows from mycelium – mass of branching

hyphae below soilO Clusters of mushrooms can have same

mycelium

ReproductionO Reproduce asexually, primarily by

releasing spores adapted to travel through air or water

O Breaking off hypha or budding also

ReproductionO Most reproduce sexually - life cycle

of the bread mold Rhizopus stolonifer

Sexual ReproductionO 2 mating types - + and 1O 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 byaO Protist group now includes as many as

300,000 speciesO Most remained unicellular – except

those leading to plants, animals, and fungi