Lecture 9/10/11: Fungi Flashcards
haven't gone over lecture 9 yet, and go over zygos/gloms in L10, L11 lichens go over
where did fungi descend from?
descended from an aquatic, single-celled, flagellated protist
How do fungi play an important role in ecosystems?
they decompose dead organisms, fallen leaves, feces and other organic materials.
what are three examples of fungi?
- yeast
- mold
- mushrooms
what is mycology?
the study of fungi, like mushrooms, molds and yeast
- understanding how they grow, reproduce, and interact with other living things
how do fungi feed (eat)?
feed by absorption (heterotrophs- can’t make their own food)
what are heterotrophs (just as a refresher)?
organisms that cannot make their own food and therefore rely on eating other organisms to get the required nutrients
what are exoenzymes?
enzymes that a cell makes and sends out of itself to break down large substances around it.
what is the benefit of exoenzymes?
very powerful, helps the organisms break down food or other materials outside their body
how do fungi use exoenzymes?
to digest plants/animals
what are the ecological roles of fungi (3 roles)? similar to the question why they are important for ecology
- decomposers
- parasites
- mutualistic symbionts
what’s another name for ‘decomposers’?
saprobes
saprobic fungi (decomposers) absorb nutrients from….
non-living organisms
parasitic fungi absorb nutrients from….
the cells of living hosts
what mainly causes plant diseases?
fungi
how do mutualistic fungi absorb nutrients? how are they beneficial to their partner?
- absorb from a host organism
- provide functions that benefit the host in some way
what are single-celled fungi called?
yeasts
what is the body structure of a mushroom from top to bottom?
TOP:
- cap
- gills (underneath the cap)
- spores (fall from the gills)
- stem
- ring or skirt (on the stem)
- volva (the bud part of the bottom)
- mycelial threads (roots)
what helps fungi absorb nutrients?
- their large surface area
- their ability to grow quickly
what are the tiny filaments (that construct most bodies of fungi) called?
hyphae
what do hyphae form?
mycelium: the network of the hyphae
how does mycelium function?
it spreads out and grows through the soil (or whatever the fungi are living on) and helps the fungus absorb nutrients
- kind of like the ‘root system’ for fungi except it can grow out to be much larger
do the fungal hyphae have cell walls?
yes
what are the cell walls of hyphae made of?
mainly of chitin
- a tough/flexible material, identical to that found in arthopods
what are the hyphae divided by?
by walls called septa
what are the fungi called that lack septa?
coenocytic fungi
what does the hyphae look like for coenocytic fungi?
one big mass with lots of nuclei
how do coenocytic fungi happen?
because the nuclei divides, but the cell doesn’t split
what is cytoplasmic division?
when the cell splits its contents into 2 separate parts, forming into 2 new cells
- happens after nuclear division
what’s the difference between nuclear and cytoplasmic division?
NUCLEAR:
- when the cell’s nucleus divides in two
- ensures each new cell gets a full set of genetic information
CYTOPLASMIC:
- when the rest of the cell divides in two (organelles, cytoplasm, etc.)
- ensures each new cell has all the tools it needs to work
what is haustoria?
something that some parasitic fungi have.
- A special type of hyphae that can enter their host’s tissues to absorb nutrients
does fungal mycelium grow fast or slow?
fast
what makes the mycelium perfect for soaking up nutrients?
its large surface area
what does fungus concentrate its energy and resources on?
it focuses on adding hyphal length and absorptive surface area
can mycelia move?
no, they are non-motile. HOWEVER, they can extend the tips of its hyphae and extend into new territory
how do fungi produce spores? asexually or sexually?
BOTH!
how do fungi reproduce?
by producing a ton of spores
how are spores dispersed from fungi?
wind or water
if the fungi spores land in a ____ place with ______, they grow into new _____.
damp; food; mycelium
what is the heterokaryotic stage?
happens during sexual reproduction
- two nuclei share the same space (cell) but haven’t combined yet-
- this is the stage before the final step of sexual reproduction, where the nuclei will eventually fuse together
when does sexual reproduction in fungi begin?
when 2 different fungi release chemicals called pheromones to signal each other
how do the pheromones help in sexual reproduction?
help the two fungi recognize each other, then the cells start to connect
the nuclei of hyphae and spores of most fungi species are ____
haploid (single set of chromosomes)
what is plasmogamy?
fusion of cytoplasm
- when two parent mycelia (fungi’s cells) combine their cytoplasm
- happens before karyogamy
what kingdoms are known as sister kingdoms?
fungi and Animalia
what data offers insights into the early evolution of fungi?
data from paleontology (study of ancient life) and molecular systematics
what did fungi evolve from?
unicellular, flagellated protist
what are fungi more closely related to?
Animalia
how many phyla of fungi are there?
5
what are the 5 phyla of fungi?
- Ascomycota
- Basidiomycota
- Zygomycota
- Microsporidia
- Glomeromycetes
what lineage of fungi diverged the earliest (most closely related to the LOCA)?
chytrids
what do chytrids have?
flagella
what members are in the clade Opisthokonta? what do they possess?
- animals
- fungi
- closely related protists
possess flagella
where does the name Opisthokonta refer to?
posterior (opistho) of flagella
where can chytrids be found?
moist areas; lakes, ponds, soil
some chytrids are saprobes. What is a saprobe?
type of fungi that acts as a decomposer, feeding on dead/decaying materials such as wood, leaves, litter, etc.
what does recent molecular evidence show about chytrids?
that they diverged the earliest in fungal evolution
like other fungi, chytrid also has…
- absorptive mode of nutrition
- chitin in cell walls
- similar key enzymes
- similar metabolic pathways
how do chytrids feed?
absorb nutrients
what do most chytrids form?
coenocytic hypae
how are chytrids unique among fungi?
they have flagellated spores (zoospores)
what are the flagellated spores in chytrids called?
zoospores
which phylum are chytrids found in?
phylum Chytridiomycota
which phylum includes fast-growing molds, parasites, and commensal symbionts?
Phylum Zygomycota
what does zygomycota look like?
fuzzy, black growth
what is an example of zygomycetes?
black bread mold (rhizopus stolonifer)
in black bread mold (zygomycota), where are the septa (walls) found?
only where reproductive cells are formed
what do horizontal hyphae do?
they spread out over food, penetrate it, and digest nutrients
what does coenocytic mean?
cell/organism that has a long or continuous structure without any walls dividing it into separate cells.
- instead of many small cells, it is one big one that has tons of nuclei floating around inside
zygosporangia are resistant to…
freezing and drying
what are microsparidia?
a phylum of fungi, unicellular parasites of animals and protists. used to be apart of zygo but now classified as their own.
- tiny
where can microsporidia only survive?
they can only survive inside the cells of their hosts
what do we use microsporidia for?
often used for pest control
what do microsporidia lack?
mitochondria
which type of fungi represents something of a taxonomic mystery? why?
microsporidia; lack mitochondira. some researchers suggest that they are an ancient branching
what does recent evidence suggest of microsporidia?
that they are highly derived parasites and may be related to zygomycete fungi
what group of fungi form symbiotic mycorrhizae with plant roots?
phylum glomeromycetes
mycorrhizal refers to…
anything related to the relationship between fungi and plant roots. ex: mycorrhizal fungi are fungi that form partnerships with plant roots. The roots help provide sugars while the fungi helps the plant absorb nutrients
what are the 2 types of mycorrhizae
- ECTOmycorrhizal
- ENDOmycorrhizal
What are ECTOmycorrhizal fungi?
fungi that form a symbiotic relationship with plant roots but STAY OUTSIDE THE PLANT’S ROOT CELLS.
- forms hyphae over the surface of the plant root and grow into extracellular spaces
What are ENDOmycorrhizal fungi?
fungi that actually penetrate the plant’s root cells and form tiny structures inside (called arbuscles) that help with nutrient exchange
- extend hyphae through the root cell wall and into tubes
what does invagination mean?
how a cell/tissue folds in on itself to form a new structure. Like when a cell membrane folds to take in substances
what are arbuscles?
the tips of the hyphae that push into plant root cells and branch into tiny treelike structures
what is the symbiotic relationship between mycorrhizal fungi and plant roots?
plants supply fungi with organic nutrients, mycorrhizal fungi supplies plant with phosphate ions and other minerals
what percentage of symbiotic mycorrhizae is present in plants?
90%
where is the phylum Ascomycota found?
marine, freshwater, and terrestrial habitats
what do ascomycetes produce?
sexual spores in sac-like asci (called sac fungi)
where do most ascomycetes bear their sexual stages?
in fruiting bodies aka. ascocarps
what are the fruiting bodies called in ascomycetes?
ascocarps
are some Ascomycota, pathogens?
yes, some. many are important saprobes (particularly of plant material) though
about 40% of ascomycete species live with ____ _______ or ______ in mutualistic associations called ________.
- green algae
- cyanobacteria
- lichens
how are some ascomycetes beneficial for plants?
release toxins that don’t harm the plant but harm any bad insects
what phylum of fungi do mushrooms/shelf fungi belong to?
phylum Basidiomycota
where does the name Basidiomycota come from?
derived from a transient diploid stage, basidium
basidiomycetes are important _______.
decomposers
what type of fungi are the best at decomposing lignin?
of all fungi, the SAPROBIC basidiomycetes are best at decomposing the complex polymer lignin (found in wood)
the life cycle of a club fungus usually includes…
a long-lived dikaryotic mycellium: two nuclei don’t fuse for a long time
what induces the dikaryotic mycelium to reproduce sexually?
environmental cues, such as rain or temperature change
what does the cap of a mushroom do?
it supports and protects a large surface area of basidia on the gills
what are the sexual spores that basidia forms called?
basidiospores
what type of reproduction is less common in basidiomycetes?
asexual
fungi and bacteria are essential for…
providing ecosystems with the inorganic nutrients responsible for plant growth
what would happen if we didn’t have decomposers?
carbon, nitrogen, and other elements would become tied up in organic matter
what do ants do with fungi?
raise fungi in “farms’ and feed them leaves.
- the fungi break down the leaves into a substance that the insects can digest
in many cases, the fungi can no longer ___ without the insects
survive
almost all vascular plants have ______ and rely on their ______ _____ for essential nutrients
mycorrhizae; fungal partners
some fungi break down plant material in the guts of ____
cows (and other grazers)
where can I find lichens?
newly cleared rock and soil surfaces (such as burned forests and volcanic flows)
how do lichen acids help break down volcanic rock?
they penetrate the outer crystals of rocks
what does the breakdown of the rock from lichens allow?
allows soil-trapping lichens to establish and starts the process of succession
- rocks into soil
what does succession mean?
refers to the gradual process of change in the species composition of an ecosystem over time
- helps ecosystems develop and recover after changes or damage
the photosynthetic partners are usually _______, ______, or _______
unicellular; filamentous green algae; cyanobacteria
what are lichens?
form of life that result from a symbiotic partnership between a fungus and either algae or cyanobacteria (or both)
- incredibly resilient
- help break down rocks into soil and provide food/shelter
what does the fungus/algae or cyanobacteria provide for each other?
FUNGUS:
- provides protection and structure
- retains water/minerals
- shades from intense sunlight with pigments
- secretes acids which aid in the uptake of minerals
ALGAE:
- provides food by leaking carbos from their cells
CYANO:
- provides organic nitrogen through nitrogen fixation
which type of pathogens have effects on forest trees such as american elms/chestnuts?
invasive ascomycetes
fungi are also serious agricultural ______.
pests
how does fungi cause economic losses each year?
some fungi (like rusts and ergots) infect grain crops which causes economic loss
which fungi infect grain crops?
rusts and ergots
why is 10-50% of the world’s fruit harvest lost each year?
due to fungal attack
some fungi that attacks food can also harm ______
humans
whats an example of a fungi on food that harms humans as well?
the mold Aspergillus
what does the mold Aspergillus contaminate? what does it produce once contaminated? what does it cause?
- improperly stored grains and peanuts
- aflatoxins
- cancer or liver damage
are the peanuts/grains carcinogenic?
Themselves, they are NOT. However, they can become contaminated with alfatoxins which ARE.
what does carcinogenic mean?
something that can cause cancer
ex: tobacco, aflotoxins, radiation
in what type of conditions does mold grow quickly?
warm and humid
______ are much less susceptible to parasitic fungi than are _____
animals; plants
what is the general term for a fungal infection?
mycosis
what common fungal infection produces the disease ringworm?
infections of ascomycetes
what is the term when the disease ringworm is on the feet?
athletes foot
how are systemic mycoses typically caused?
by inhaled spores
what is coccidiodomycosis?
a systemic mycosis that produces tuberculosis-like symptoms in the lungs.
- very deadly
what is coccidiodomycosis known as (hint: very deadly)?
a potential biological weapon
what does systemic mycosis mean?
a fungal infection that spreads throughout the body, affecting internal/external organs and systems.
- can enter the body through respiratory or open wounds
some mycoses are ________, occurring only when a change in the body’s microbiology, chemistry, or immunology allows the fungi to grow unchecked.
opportunistic
how are fungi commercially important?
SCIENCE:
- important in science and tech
medicine such as antibioitcs like penicillin
FOOD:
- gives certain cheeses
- yeasts are key in making bread, beer, and wine
- gives certain cheeses their unique flavours
- truffles (type of fungi) are loved for their rich flavour
what does dikaryotic mean?
‘two nuclei”
- cells have 2 diff nuclei
what is karyogamy?
fusion of nuceli
- the haploid nuclei from the two parents fuse and produce diploid cells
the sexual processes of karyogamy and meiosis generate _____ _______
genetic variation
do the diploid cells exist for a long time in most fungi?
no. short-lived
what do the diploid cells go through to make new haploid spores?
meiosis
some fungi that can reproduce asexually grow as….
mold
where do yeasts live?
liquid/moist habitats
how does yeast reproduce? sexually or asexually?
asexually
- by simple cell division or budding of small cells
what are the fungi called that have no known sexual stage?
‘deuteromycetes’ or ‘imperfect fungi’
what is the asexual reproduction process for fungi?
produce spores without needing to combine with another fungus
- no fusion of cells is involved
- does not involve plasmogamy, karyogamy, or meiosis
what is the sexual reproduction process for fungi (simple)?
- Plasmogamy: cytoplasm fuses
- Heterokaryotic stage: single cell contains 2 different nuclei, one from each parent
- Karyogamy: nuclei fuse
- Meiosis: cells divide and produce haploid spores
- Germination: spores disperse, create new mycelium, and repeat
what is mycelium?
the main part of the fungi. Made up of a network of thin thread-like structures called hyphae.
- helps the fungi absorb nutrients
zygomycota reproduce both _______ and _______.
sexually; asexually
what happens in ASEXUAL reproduction for zygomycota?
- produce spores called sporangiospores
- then form into structures called sporangia at the tips of upright hyphae
- released and grow into new fungi without needing another fungus
what happens in SEXUAL reproduction for zygomycota?
- plasmogamy of opposite mating types form a thick-walled structure called zygosporangium
- produces zygospores or rhizopus
if bad conditions, rhizopus may reproduce.
If conditions get better, the zygosporangia undergoes meiosis and release haploid spores, called zygospores.
what do nitrogen-fixing lichens do?
add organic nitrogen to some ecosystems
some lichens can survive in what type of conditions?
severe cold/desiccation (can dry out completely but still come back to life when they get water again)
what does desiccation mean?
drying out completely
how do lichens absorb water in dry habitats?
from fog or rain
how are lichens good for air quality?
they are sensitive to air pollution. A dying lichen is a warning sign of deteriorating air quality
whats the difference between plant cell walls and fungi cell walls?
plant cell walls are made of cellulose, while fungi cell walls are made of chitin
where are basidiomycota found?
club fungi, therefore terrestrial (forests usually)
where are ascomycota found?
anywhere. just sacs
where are chyrtids found?
aquatic/moist environments
where are zygomycota found?
soil or decaying material
where are glomermycota found?
sybmiont with plant roots therefore soil
