Phungi part 1 Flashcards
Molecular phylogeny places fungi in the ____ which also includes animals
Opisthokonts
Fungi and animals’ common ancestor was a
protist that was singe celled with a posterior flagella
Fungi function in soil
breakdown organic material and recycle nutrients
Shared derived traits of fungi
absorptive nutrition, hyphae and mycelia, chitinous cell wall
Absorptive nutrition
Fungi are absorptive heterotrophs
Fungi are ____ eukaryotes
chemoheterotrophs
Fungi feed by
absorption of nutrients from outside of their body (absorptive heterotrophs).
exoenzymes
enzymes secreted by Fungi to break down complex molecules into smaller organic compounds (external digestion)
Fungi can digest __ from animals and ____ from plants
chitin and keratin from animal tissues, cellulose and lignin from plant tissues
After external digestion, fungi will absorb
Simple organic molecules (e.g. sugars, amino acids)
Fungi use ____ to obtain food in their environment
growth (they are non-motile)
hyphae
numerous cylindrical, branched, thin (one cell thick), filled with cytoplasm and organelles multicellular filaments that absorb nitrients
Mycelium
network of branched hyphae adapted for absorption formed by hyphae when fungi encounter a food source
Examples of fungi that do not make mycelia
Single-celled fungi (yeasts) live in moist, nutrient-rich environments
Mycelium’s filamentous structure maximizes
its surface area / volume ratio (better for food absorption and enzyme secretion)
Chitin
a glucosamine polymer (a strong and flexible material)
Hyphae are protected by walls made of
Chitin
The earliest fungal lineages are
(coenocytic) aseptate
Coenocytic fungi hyphae
The hyphae of coenocytic fungi form a continuous compartment, with many nuclei but with no dividing cell walls.
Thus, they are continuous cytoplasmic mass with
thousands of nuclei.
After coenocytic fungi came
septa formation
Septa formation
- a (cross-walls) that divide the cytoplasm into separate
cells. - The majority of fungi species are septate.
- Pores allow cell-to-cell movement of
water and solutes. - Septate fungi have single nuclei per cell.
Fungi reproduce by
producing vast numbers of spores
Fungal spores are produced by
mitosis and meiosis
Fungal mycelia are___ that produce ___spores that grow to produce hyphae
1n
1n
Spores are dispersed by
wind, water, animals
During sexual reproduction, many fungi produce spores within _____ that enhance spore dispersal.
multicellular fruiting bodies
heterokaryotic stage
A stage where there are genetically distinct haploid nuclei in one cell
plasmogamy
cell fusion
karyogamy
nuclear fusion
Fungal nuclei are ___ except for ____ stages
haploid (1n)
transient diploid stages formed during the sexual life cycles
Monokaryotic
single, identical nuclei
separate hyphae are ___karyotic
monokaryotic
homokaryotic
multiple identical nuclei
Coenocytic hyphae are
homokaryotic
Sexual reproduction requires
the fusion of hyphae from different mating types
Plasmogamy
the union of cytoplasms from two-parent mycelia
heterokaryon
haploid nuclei that exist in a cell before they fuse
Separate fungi
the haploid nuclei pair off two per cell during mitosis
forming a dikaryotic mycelium
Kayogamy
nuclear fusion where haploid nuclei fuse to form a diploid cell (zygote), does not happen fast (can take centuries before it happens)
The diploid undergoes meiosis and produces:
haploid spores
____ allows mating and spore production to occur at optimal times
Separation of plasmogamy and karyogamy
Do fungi show alternations of generations?
no
What produces genetic variation
Karyogamy and meiosis
Do fungi have gametes?
no
How is a zygote formed
by the fusion of regular haploid nuclei
Fungi can reproduce asexually by
- Fragmentation: fragments of hyphae can grow into new mycelia.
− Budding: unicellular yeasts reproduce asexually by budding
Asexual spores
form visible mycelia and produce haploid asexual spores by mitosis
Do molds and yeasts have no sexual stages?
no
Opishokonts clade
fungi, animals, and related protists
Unicellular nucleariids and unicellular choanoflagellates show that
multicellularity arose separately in animals and fungi
Kingdom fungi is a ____ group
monophyletic
The ancestor of fungi was
an aquatic, single-celled, flagellated protist
Phyla of fungi
- Chytrids (phylum Chytridiomycota) − Zygomycetes (phylum Zygomycota) − Glomeromycetes (phylum Glomeromycota) − Ascomycetes (phylum Ascomycota) − Basidiomycetes (phylum Basidiomycota)
Chytrids
- first diverging group of fungi, paraphyletic group,
- Found in aquatic or moist habitats; some in soil, estuaries, or on/inside digestive tract of animals
- unicellular; others form coenocytic thalli
(body) , usually with no true mycelium (only some form hyphae) - having motile flagellated asexual spores, called zoospores
- decomposers, parasites, or mutualists
- cell walls made of chitin and utilize external digestion
Zygomycetes
- produce hyphae without septa
- A paraphyletic group with <1% diversity of fungi
- fast-growing molds, parasites, and commensal symbionts
Zygosporangia
- the site of karyogamy and then meiosis
- resistant to freezing and drying can survive unfavourable conditions
Glomeromycetes
- form symbiotic relationships with the roots of plants
- Monophyletic group of low diversity
- reproduce via asexual soil spores
ecological importance of glomeromycetes
form arbuscular mycorrhiza (endomycorrhiza) with >80% of plant species.
Dikarya fungi
- form seperate hyphae following plasmogamy
- Dikarya includes all edible mushrooms; yeast species used for bread, beer, and cheese production; major wood-rotting fungi; and pathogens of crops and humans
Two monophyletic Dikarya groups
Ascomycetes and Basidiomycetes
Dikarya fungi during heterokaryotic stage
produce dikaryotic cells (n + n) that contain two haploid
nuclei, one from each parent
Ascomycetes
the dikaryotic stage is short-lived
Basidiomycetes
the dikaryotic stage is often long-lived and dominate the mycelium
Ascomycetes
- Found in marine, freshwater, and terrestrial habitats.
− Vary in size from unicellular yeasts to those forming elaborate, multicellular fruiting bodies - wood-rotting fungi (decomposers), many ectomycorrhizal species, plant and animal pathogens, the fungal partner in most lichens, and baking/brewing yeasts
Ascomycetes are defined by
the production of sexual spores in saclike asci contained in fruiting bodies
How ascomycetes reproduce
asexually by enormous numbers of asexual spores called conidia
Concodia
asexual spores in ascomycetes
Conidia are formed
produced asexually at tips of specialized hyphae called conidiophores
Basidiomycetes
familiar toadstools, puffballs, shelf fungi, ectomycorrhizae, and plant pathogens
The life cycle of basidiomycetes usually includes
long-lived dikaryotic mycelium
Basidiomycetes are defined by
club-like structures called basidia, transient diploid stages in the life cycle (“club fungi”)
Basidiomycete mycelia reproduce by
sexually in response to environmental stimuli by producing elaborate, multicellular fruiting bodies, basidiocarps
Basidiocarps
multicellular fruiting bodies produced by Basisiomycete
Gills
thin vertical sheets of mycelia contained in basidiocarp
Gills are lined with
millions of basidia
