1. Fungi
Section 18-2

2. What is a Fungus? They are heterotrophic eukaryotes with a cell wall
They obtain food by extracellular digestion and absorption
Enzymes are released to break down food particles outside their bodies
Digested molecules are then absorbed

3. What is a Fungus? Most are multicellular (except yeast)
Can be parasitic or decomposers
They look more like plants, but are technically more like animals:
They have cell walls like plants, but the cell wall is made of chitin not cellulose (chitin is found in the exoskeletons of insects)
They store energy as the starch glycogen, like animals and are heterotrophic

4. Characteristics of Fungi
Evolved around 430 million years ago
All multicellular fungi have the same basic structure:
Hypha (pl. hyphae) – a threadlike filament whose cells have varying numbers of nuclei
Mycelium – mass of hyphae that grows into the food source (this is the part that secretes the enzymes for digestion)
Fruiting body – the reproductive part of the fungus that produces spores

5. Reproduction in Fungi Can be asexual: Some produce spores
Some reproduce by fragmentation of hyphae

6. Reproduction in Fungi Can be sexual:
There are two mating types - + hyphae and – hyphae
When opposite hyphae meet, some of their filaments fuse
Their nuclei then fuse, undergo meiosis, and produce spores

7. Types of Fungi Phylum Zygomycota (called zygomycetes)
Also called bread molds or common molds
Reproduction has two phases, one asexual and one sexual
An example is Rhizopus stolonifer (black mold)

8. Types of Fungi Phylum Ascomycota (called ascomycetes)
Also called sac fungi
30,000+ species of mildews, molds, and yeasts
Examples include truffles, baker’s yeast

9. Types of Fungi Phylum Basidiomycota (called basidiomycetes)
Fruiting bodies form mushrooms (above ground)
Many are delicious, some can be poisonous

11. Types of Fungi Phylum Deuteromycota (called deuteromycetes)
Also called “imperfect” fungi because scientists have never been able to identify the sexual stage of their life cycle
Example is Penicillium, which is used to make the antibiotic penicillin; also the fungus that causes athlete’s foot

12. Lichens Look like moss, usually seen growing on tree trunks or rocks
Not actually a single organism – represents a symbiotic partnership between a fungus and some photosynthetic organism, like a bacterium or algae
The autotroph performs photosynthesis, which provides nourishment for the fungus
The fungus provides the autotroph with water and minerals that it removes from the rock or the tree