Fungi

Overview of Fungi

• DNA shows Fungi are closely related to animals
• Ancestor likely aquatic, single cell protist
• Likely colonized land at the same time as plants
• Possible symbiotic relationship (mycorrhizal)

Basic Characters

• Chemoheterotrophs: Get energy from chemicals in environment
• Exoenzymes: enzymes outside of body,
• External digestion
• Break down large molecules to absorb
• Digest plant (cellulose / lignin) and animal (chitin / keratin) tissue
• Three types
• Decomposers: Break down and absorb non-living organics
• Parasites: Absorb living host nutrients
• Mutualists: Absorb nutrients from host, but also give back
• Chitin: strong and flexible, makes up cell walls
• Hyphae: network of tiny filaments that make up the mycelium
• Mycelium: Interwoven mass of fungal hyphae
• Makes up the bulk of fungi
• The visible, above ground mushroom is just the fruiting body and reproductive structures (like flowers of plants)
• Fruiting bodies produce spores
• Hyphae are filaments (string-like)
• High SA:V ratio (Surface Area to Volume)
• Increased enzyme secretion and food absorption
• Grows rapidly
• Only grows in length (doesn't get wider)

Fungal Reproduction

• Different from plants
• Undergoes Asexual or Sexual reproduction
• Spores: haploid (1N) and produce the hyphae
• Created through meiosis OR mitosis
• (plants use ONLY meiosis for spores)
• Some fungi can switch throughout their life
• Spores resistant to desiccation and aid in dispersal (like plants)

Diversity of Fungi

• Greek "myco-" = fungi
• Five phyla of fungi (say that five times fast!)

Phylum Chitridiomycota (Mastigomycota)

• Mostly in freshwater
• Some free-living: digest dead organic matter
• Some parasitic: digest living tissue of host
• Host: plant, animal or fungus
• Major cause of global amphibian decline

Phylum Zygomycota

• "Bread mold"
• Live in soil and dead organics
• Have few parasites or predators

• Can think of as a "glob" of stuff
• All species symbiotic with plant roots
• 90% of plants interact with this phylum
• Mutualistic
• Supplies minerals and nutrients to roots
• Receives energy from photosynthesis

Phylum Ascomycota

• "Sac-fungi"
• Largest phylum
• size range from single celled yeast to large truffles
• Asci: sac like structure that produces spores

• "Club-fungi"
• Known for mushrooms and toadstools (sexual structures)
• Basidiocarp: cap-like structure, defining character Example: Common white mushrooms at market
• Cap: contains the gills
• Gills: vertical sheets of tissue
• contain Basidia: produces spores
• Decompose dead plant matter (lignin)
• Some parasitize plants

Appearance of Fungi

• Fungi as Molds
• Asexual
• grow rapidly
• Produce "fuzzy hyphae" on organic matter
• Fungi as Yeasts
• Unicellular in aquatic or moist habitat
• Asexual
• buds pinch off from parents
• Some fungi can alternate between yeast and hyphae
• Depending on conditions
• Hyphae when favorable