Fungi Part 2 Flashcards
Chytrids
unicellular, flagelated
Zygomycetes
asexual reproduction, most important for dispersal, sexual reproduction via zygosporangia
Glomeromycetes
Arbuscular mycorrhiza;
no sexual reproduction
Ascomycetes
Short-lived dikaryotic stage;
sexual spores produced in
asci; numerous asexual
spores (conidia)
Basidiomycetes
Long-lived dikaryotic mycelium; sexual spores produced in basidia by elaborate fruiting bodies (basidiocarps)
Most fungal phyla can be differentiated by
the use of reproductive structures, eocological lifestyles,
Molds ecological lifestyles
rapidly growing, asexually reproducing fungi.
Molds produce ___ on the surface of organic\ substrates
fuzzy growth of
hyphae
Molds are classified when
sexual structures emerge
Yeasts
unicellular fungi that inhabit liquid or moist habitats
Yeast reproduction
asexually: bud off daughter cells following mitosis
molds are found in
in zygomycetes (e.g. Rhizopus) or ascomycetes (e.g. Penicillium)
Yeasts found in
ascomycetes (e.g. Saccharomyces cerevisiae) or
basidiomycetes
Mycorrhiza
mutually beneficial (symbiotic) associations between fungi and the roots of vascular plants
Mycorrhizal fungi supply plant roots with
water and nutrients, such as phosphorus and nitrogen, from the soil and in return receive carbohydrates from their host
Two main types of mycorrhizal
Ectomycorrhiza and Endomycorrhiza
Hyphae of _____ surround, but do not penetrate, root cells
ectomycorrhizal fungi
Mycelium forms: _______ into surrounding soil.
a dense sheath of hyphae (mantle) over the root; hyphae extend
Ectomycorrhizae restricted to
mostly wood plants
most common type of endomycorrhizae
arbuscular mycorrhiza
arbuscular mycorrhiza hyphae
- Hyphae penetrate through cell walls of root cells, forming invaginations of the root cell membrane
- provide a large surface area for nutrient exchange
arbuscular
branched hyphal structures in arbuscular mycorrhiza
arbuscular mycorrhizae form a _____ group
monophyletic
Ecological roles of Fungi
decomposers, mutualists, pathogens
Saprotrophic nutrition
Saprotrophic nutrition is the chemoheterotrophic extracellular digestion of dead or waste organic matter
Decomposers break down complex organic compounds into
inorganic mineral forms
Fungi are critical to the cycling of
carbon and nitrogen, converting dead organic
matter back into ammonium (NH4+), CO2, and water.
The most abundant dead organic matter in soils is from
plant tissues: cellulose and lignin
Hyphal growth of fungi is adapted to
searching through soil for plant matter
“Fairy rings” result from
- outward growth of decomposer mycelia
- Release of nutrients from fungal decomposition of soil detritus at the outer edge of the mycelium ring stimulates plant growth
Fungi have repeatedly evolved mutually beneficial relationships with
plants, algae, cyanobacteria, and animals
fungal endophytes
Plants host harmless symbiotic fungal endophytes, fungi that live in the intercellular spaces of leaves or other plant tissues.
How the relationship between fungal endophytes and plants are mutualistic
- Endophytes enhance the health and survival of the host plant
- Endophytes often produce toxins that deter herbivores and defend against pathogen infections
- The endophyte receives organic carbon from the plant host
Most endophytes are
Ascomycetes
Lichen
a mutually beneficial (symbiotic) association between a
photosynthetic microorganism and a fungus.
Lichens appear, function, and even reproduce as _____
single organisms
___________ occupy an inner layer below the lichen
surface
algae or cyanobacteria
Algae provide _____ compounds; nitrogen-fixing
cyanobacteria also provide ______ (algae and cyanobacteria in lichen)
organic carbon
organic nitrogen
Fungi provide for cyanobacteria in lichen:
an environment for photosymbiont growth (protection,
free from competition, fungal mycelia retains water and minerals).
Asexual reproduction of lichen
Asexual reproduction is by fragmentation or formation of soredia, small clusters of hyphae containing embedded algae
Lichens aid in the breakdown of
rock, volcanic flows, and burned forests
How lichens help with breaking down stuff
Lichen secretes weak acids that degrade the substrate
The swelling of hyphae in cracks promotes fracturing of rock.
Lichens trap windblown particles
Powdery mildews
fungi that coat leaves and fruits by penetrating cells with special hyphae
Ergot
- Ergot replaces seed with its own mycelium mass that produces alkaloids that can cause ergotism in humans and other mammals when contaminated grains are consumed.
− Ergots alkaloids include lysergic acid derivatives, which are similar to psychedelic drugs (LSD), that effect circulation and neurotransmission
Dutch elm disease
- was accidentally introduced into North America in ~1930s in imported elm wood
- Ascomycete fungi
- tree blocks it’s xylem
Blue-stain fungus
- spread by mountain pine beetle
- fungus kills the pine tree by clogging and destroying the tree’s vascular tissues
mycosis
- a fungal infection of animals or humans
- a cutaneous fungal infection occurs on the outer layer of the skin (fungus can enter the system after traumatic injury to the skin)
Systemic fungal infections
occur when a fungal pathogen spreads widely inside the host’s body to many organs
Histoplasmosis
- fungus grows in soil contaminated with bird or bat
droppings - Disturbing the substrate leads to inhalation of conidia spores
- primarily effect the lings
