Fungi Flashcards
FUNGI
eukaryotic
nonmotile, with rigid cell walls
nonphotosynthetic, chemoheterotrophic – obtain nutrients by absorbing
small organic compounds through its plasma membrane
has ergosterol in plasma membrane
mostly aerobic or facultatively anaerobic
FUNGAL
MORPHOLOGY
CELL WALL
cross-linked multilayer
Chitin – unbranched polymer of
β-1,4-linked N-acetylglucosamine
Glucans – glucose polymers (e.g
α-1,3-glucan, β-1,3-glucan, and β-
1,6-glucan)
Mannans – polymers of mannose
(e.g. α-1,6-mannose)
Melanin – in dematiaceous fungi
GROWTH
FORMS OF
FUNGI
Yeast
Mold
Dimorphic fungi
YEAST
nonfilamentous, unicellular, with spherical/oval cells
facultatively anaerobic
◦ w/ O2 – metabolism of carbohydrates into CO2
and H2O
◦ w/o O2 – fermentation of carbohydrates to CO2
and ethanol
MOLD
filamentous, multicellular
Thallus (body) – formed by mycelium (mass of intertwined hyphae)
◦ Hyphae – long filaments of cells joined together
septate hyphae
Coenocytic (non septate) hyphae
Pseudohyphae
◦ Spores
HYPHAE
Structural Classification
•Septate Hyphae – have cross-walls between
uninucleated cells
•Coenocytic Hyphae – long continuous cells
with many nuclei
Functional Classification
•Vegetative/Substrate Hyphae – penetrate
the supporting medium, anchor the colony,
and absorb nutrients
•Reproductive/Aerial Hyphae – project
above the surface of the mycelium and bear
reproductive spores
DIMORPHIC
FUNGI
exhibit 2 forms of growth –
either as mold or yeast
temperature-dependent:
◦ 37° C – yeastlike;
reproduce by budding
◦ 25° C – moldlike; produce
hyphae
FUNGAL
REPRODUCTIONS
ASEXUAL
•BUDDING
•FISSION
•FRAGMENTATION OF HYPHAE
•ASEXUAL SPORES
•CONIDIOSPORES
•SPORANGIOSPRORES
SEXUAL
•SEXUAL SPORES
YEAST AND
MOLD
REPRODUCTION
Yeasts
•Budding
•Fission
•Asexual Spores
•Sexual Spores
Molds
•Fragmentation of Hyphae
•Asexual Spores
•Sexual Spores
Budding Yeasts
•divide unevenly
•parent cell forms a protuberance (bud) on its outer surface, bud elongates,
the parent cell’s nucleus divides, and one nucleus migrates into the bud
•Pseudohyphae – short chain of cells formed by buds that fail to detach
themselves
Fission Yeasts
•divide evenly
•parent cell elongates, its nucleus divides, and 2 offspring cells are produced
ASEXUAL SPORES
formed from the hyphae of 1 parent
organism via mitosis
produces an organism identical to the parent
more frequent mode of reproduction
2 types
◦ Condiospore/Conidium – spores not enclosed
w/n a sac at the end of an aerial hypha called
conidiophore
◦ Sporangiospore – spores enclosed w/n a sac
called sporangium at the end of aerial hyphae
called sporangiophore
SEXUAL SPORES
formed from the fusion of nuclei of 2 opposite mating strains of the same
species
produce an organism with the characteristics of both parent organisms
less frequent mode of reproduction
3 phases of sexual reproduction
1. Plasmogamy: A haploid nucleus of a donor cell (+) penetrates the cytoplasm of a
recipient cell (-).
2. Karyogamy: The (+) and (-) nuclei fuse to form a diploid zygote nucleus.
3. Meiosis: The diploid nucleus gives rise to haploid nuclei (sexual spores), some of which
may be genetic recombinants.
FUNGAL LIFE CYCLE
Teleomorph • sexual stage
Anamorph • asexual stage
Holomorph • whole fungus, including the anamorph and teleomorph
Perfect Fungi • has both sexual and asexual stage
Imperfect Fungi • has asexual stage only; no sexual stage
ZYGOMYCOTA (OBSOLETE)
conjugation fungi
lower fungi
saprophytic molds with coenocytic hyphae
Spores
◦ Sexual – zygospores
◦ Asexual – sporangiospore
now split into Mucoromycota and Zoopagomycota
