Fungi Flashcards
Why are fungi not well known?
Their is an estimated 1.5 million species but only 7% of predicted land fungi have been documented
What is a major role of fungi in ecosystem?
he decomposition of plant and animal tissues; play a critical role in cycling carbon
What is the growth and nutrition charcatersitcis of fungi?
heterotrophs - depend on preexisting organic molecules for carbon and energy
absorb organic molecules directly through their cell walls
secrete enzymes that break down complex organic molecules into simpler compounds that can be absorbed
What are most fungi?
multicellular (except yeast) consisting of hyphae that make up the mycelium
What are hyphae?
highly branched filaments - that increase surface area for absorption of nutrients
What is the mycelium?
a network of hyphae - even greater surface area
What is the largest fungi?
Armillaria ostoyae - over 2000 acres - Blue Mountains of Oregon - weighs hundreds of tons
What are septate hyphae?
hyphae with partitions or cross-walls, often with central pores
What are aseptate hyphae?
no cross-walls in hyphae - ‘contained in a common cytoplasm’ - multinucleate (=coencytic)
What are the cell walls of hyphae?
made of chitin and glucans; more resistant to microbial degradation than cellulose
What is digestion in fungal hyphae?
external, osmotrophic nutrition - secrete enzymes onto food sources, then absorb (osmotically) smaller molecules
What is energy storage in hyphae?
glycogen (like animals and bacteria)
Which fungi don’t produce hyphae?
yeasts
What are yeasts?
single-celled, in moist nutrient rich environments. reproduce by budding.
WHat is budding? (yeasts)
small outgrowths form on original cell that increases in size and eventually breaks off to form a new, identical cell
What are humans uses of yeast?
ferment plant carbs to produce leavened bread and alcoholic bevs
What is fermentation?
chemical process by which molecules such as glucose are broken down anaerobically
What are Saprophytes? How do they get energy?
decomposers sequestering food/energy from organic material of dead organisms
parasite/predators - how do they get energy? (fungi)
organic material from living organisms, by infection or consumption
How do symbionts get energy?
organic material via mutualistic relationships with algae and/or cyanobacteria
What are the ecological roles of fungi?
important biomass
decomposers of the biosphere
parasites/predators, disease agents
symbiotic relationships
What are ecological roles of decomposers?
break down organic material from bodies of dead organisms
release CO2 into atmosphere
return nitrogen and minerals to soil
What is a common biproduct of decomposers?
produce toxic secondary metabolites (mycotoxins) - capable of causing disease and death in both humans and other animals
What are some types of fungal pathogens?
rusts, smuts, and molds (cause huge losses in agricultural production)
What are aboveground plant infections usually transmitted by?
fungal spores
What are belowground plant infections usually transmitted by?
hyphae that penetrate the roots
What are the 3 wasy that fungi can infect plants?
through wounds
through stomata
through epidermal cells directly
What are ways in which fungi are predators?
trap living animals by forming sticky traps with hyphae, or lasso their prey
What are mycorrhizal fungi?
mutualistic relationship - supply plant roots with nutrients such as phosphorus and nitrogen from the soil and, in return, receive carbohydrates from their host plants
What are Lichens?
stable associations between a fungus and photosynthetic microorganisms, green algae or cyanobacteria
What is role of fungus in Lichens?
fungal hyphae that take up water and nutrients from the soil
What is the role of photosynthetic microorganisms in lichens?
provide energy to fungi for growth
Where do Lichens thrive?
harsh environments - arctic, deserts
bare soil, sun-baked rocks, tree trunks, alpine peaks, interior of rocks
What are three forms of Lichen growth?
Crustose, Foliose, Fruticose
What is appearance of Crustose lichen?
flattened and adheres firmly to substrate, ‘crusty’ appearance
What is appearance of Foliose lichen?
leaf-like appearance
What is appearance of Fruticose lichen?
erect and branched, ‘shrubby’ appearance
What is the ecological importance of lichens?
biogeochemical weahtering of rock (primary succession)
Soil formation (primary succession)
Soil nitrogen enhancement (for those with cyanobacteria)
Nio-indicators of toxic compounds/pollutants
What is the economic value of fungi?
yeast - baking, brewing
Flavours and aromas (lactic acid - cheese, soy sauce
medicines - antibiotics (penicillin), cyclosporine, statins used to decrease cholesterol
food - mushrooms, morels, truffles
biological pest control
How do fungi reproduce?
by producing fruiting bodies that release spores
What is spore dispersal like in fungi?
carried by wind, water, attached to or within animals
aquatic have flagella to swim
large number of spores produced
What triggers spore formation?
a shortage of resources
How do spores form?
meiotic cell division as part of sexual reproduction, or form asexually
How does asexual spores produced?
within sporangia that form at ends of erect hyphae, facilitating the release of the spores into the air
What do fruiting bodies do?
producing by some fungi facilitate the dispersal of sexually produced spores
What are examples of fruiting bodies?
mushrooms, stinkhorns, puffballs, bracket fungi, truffles
What is the structure of fruiting bodies?
highly ordered and compact - grow from the mycelia (but more organized - constructed of hyphae
What are the 3 phases of fungal sexual reproduction?
plasmogamy
karyogamy
meiosis
What happens in plasmogamy?
fusion of the cytoplasm of 2 parent hyphae (or mating types)
What happens in karyogamy?
fusion of nuclei from different parents (2n nucleus)
What happens in meiosis?
zygote divides and produces haploid spores
What is the heterokaryotic stage?
after plasmogamy the haploid nuclei retain their independent identities (not fused).
WHat do heterokaryotic cells (genetically distinct nuclei maintained) create?
Dikaryotic (n+n) mycelium
What is the diversity of fungi?
high about 75,000 species described (which is only 7% of predicted land fungi species)
What are Chytrids (Chytridiomycota)?
most decomposers (saprophytic) some pathogens
unicellular with rhizoids (not true hyphae) used for attachment and feeding
about 1000 species living in aquatic habitats
How do Chytrids reproduce?
form flagellated gamete cells (only fungus with motile cells) that swim through their aqueous enviornment
What are Zygomycetes (Zygomycota)? key traits?
some decomposers, others live on and in plants, animals, and even other fungi
traits: aseptate hyphae, mycelia, and production of aerial spores
What is an example of a Zygomycete?
black bread mold - Rhizopus
specialist on substrates like bread, ripe fruits, and the dung of herbivores
What are Glomeromycetes?
occur in association with plant roots
80% of all vascualr plants have glomeromycete - root symbiosis via endomycorrhizal relationships
What is the advantage of Glomeromycete (endomycorrhizae) relationships for plants?
dramatically increase their nutrient uptake from the soil
What are plant mycorrhizae benefits??
fungi that increase plant’s ability to capture water and essential nutrients (P, N, Zn) by increasing surface area for absorption
protect against attack by pathogenic fungi and nematodes
What are mycorrhizae benefits from plant?
plant provide mycorrhizae with carbohydrates and essential vitamins
What are the two types of mycorrhizae and what type of fungal growth forms/phylum are they?
Endomycorrhizae = Glomeromycota
Ectomycorrhizae = mostly Basidiomycota
What features does clade Dikarya include?
98% of all described fungal species
septate hyphae
every mitotic division is accompanied by the formation of new septae
What are examples of Dikarya fungi?
all edible mushrooms, yeast used in beer,bread, and cheese; the major wood rotting fungi, and pathogens of both crops and humans
WHat are the 2 clades represented by the term Dikarya?
Ascomycetes and Basidiomycetes
What are Ascomycetes?
sac fungi; nuclear fusion (karyogamy) and meiosis take place in an elongated saclike cell called an ascus
What are basidiomycetes?
club fungi; nuclear fusion (karyogamy) and meiosis take place in a club-shaped cell called a basidium (base or pedestal)
What are some examples of ascomycetes?
mold, mildew, brown rot, chestnut blight, Dutch elm disease, yeast, morels, truffles
What are key features of Ascomycetes?
unicellular or filamentous
septate hyphae
sexual spores are called ascospores (haploid)
How many species of Ascomycetes are there? % of species?
48,000 (64% of fungal species)
What are Lichens?
association between fungus (mycobiont) and algae or cyanobacteria (photobionts)
What clade do most lichens fall under?
Ascomycota (98%)
How does sexual reproduction work in an Ascomycete?
Ascus -saclike structure within which haploid ascospores are formed following meiosis, Asci usually contain 8 ascospores
Ascocaprs are the fruiting bodies of ascomycota containing asci with ascospores
What are the 3 types of Ascocarps?
Cleistothecium
Perithecium
Apothecium
What is the shape of a Cleistothecium?
ovoid or spherical ascocarp with no opening
What is the shape of a Perithecium?
flask-shaped ascocarp with terminal pore
What is the shape of a Apothecium?
cup or saucer-shaped structure with asci on upper surface
What is an example of a fungi with a Cleistothecium?
Powdery mildew
What is an example of a fungi with a Perithecium?
Sordaria sp.
What is an example of a fungi with Apothecium?
foliose lichen
What are the 3 major groups of Basidiomycetes?
smuts, rusts, multicellular fruiting bodies (e.g. mushrooms)
How many species of Basidiomycetes are there?
25,000 (34% of all described fungi)
What is a Basidiocarp?
complex structure of tightly woven dikaryotic hyphae (n+n)
What is a Basidium?
club-shaped spore producing struture
