MOST FUNGI ARE DECOMPOSERS • FUNGI ABSORB MATERIALS FROM THE ENVIRONMENT • INCLUDE MUSHROOMS, MOLDS, & YEAST • CAN BE HELPFUL OR HARMFUL TO OTHER ORGANISMS
Jan 19, 2018
MOST FUNGI ARE DECOMPOSERS
• FUNGI ABSORB MATERIALS FROM THE ENVIRONMENT
• INCLUDE MUSHROOMS, MOLDS, & YEAST
• CAN BE HELPFUL OR HARMFUL TO OTHER ORGANISMS
Absorb Material from Environ.• Most are decomposers
that absorb nutrients & leave behind simpler compounds.
• Are heterotrophs (get energy from living or once living matter).
• They and bacteria decompose leaves, shed skin, animal droppings, etc.
• Except for yeast, most fungi are multicellular.
• Typical fungus made of reproductive body & network of cells forming threadlike hyphae (one cell thick). A mass of hyphae form a mycelium. The cells release chemicals, digesting surrounding materials & absorbing nutrients.
• Fungi reproduce sexually (with spores) or asexually. Spore = one reproductive cell that can grow into new fungus.
Absorb Material from Environ.• A single mushroom can make
a billion spores. • Spores are released into air &
spread by wind long distances.• Some spore have tough
coverings protecting them for years until conditions are right for growing.
• Fungi can reproduce asexually when hyphae break off to form anew mycelium. Yeast (single cell fungi) reproduce by cell division, budding & spores.
Mushrooms, Molds & Yeast• One mushroom may be from a mycelium that fills the
size of a football field.• Some mushrooms are poisonous & some edible. The
cap is where spores are made, and hyphae fill the cap & stalk.
• MOLDS: fuzzy growth sometimes seen on food; hyphae grow into food & digest it as they grow.
• Some Penicillium mold are used in Brie & blue cheese. Some aspergillus mold is used in soy sauce. Trichoderma mold grows in soil & makes digestive chemicals used to give blue jeans a stonewashed look.
Mushrooms, Mold, & Yeast• Molds may cause disease. Fungal molds cause athlete’s foot; others affect plants (Dutch elm); Penicillin is an antibiotic from Penicillium fungus.
• Molds reproduce via spores mostly carried by air; the “hat thrower” fungus Pilobolus grows in animal droppings & shoots off its spore cap via water pressure to land a few feet away to hopefully be eaten in the grass by a cow.
Mushrooms, Molds & Yeast• Yeasts are single
celled fungi. Grow in moist environments (plant sap, skin, shower curtains)
• If yeast growing on human skin reproduces too rapidly, it may cause disease.
• Used in food products (breaks down sugars making CO2 gas to make bread rise & give wine/beer its bubbles).
Fungi can be Helpful or Harmful • Fungi & bacteria are Earth’s decomposers (even live
in sea to recycle materials for ocean-living organisms).• Hyphae grow into & decompose other organisms
material (to turn dead tree back into useful nutrient rich soil or to kill off Dutch elm)
• Most hyphae surround plant roots providing nutrients for plant, while plant provides food.
• Lichen = fungal hyphae mixed around single celled algae. Lichen live in arctic & desert, even bare rock, eventually breaking it down into soil.
Helpful/Harmful Fungi• May make toxins (In
1845 fungus infected Ireland’s potato crop, dropping causing Ireland to go from 8 million to 4 million people; many died of disease, starvation and others left, many to US. Today, many banana crops are being destroyed by fungal disease.
• Penicillin from a fungal toxin kills off many types of bacteria, so is used as an antibiotic.