Chapter 31- FUngi Flashcards
What are three key traits most fungi share?
Method nutrition is derived
heterotrophs
Forms multicellular filaments
How do fungi absorb nutrients?
secrete hydrolytic enzymes
What do enzymes excreted by fungi do? (2)
Breaks down complex molecules
Break down cell walls to absorb nutrients
What three roles can fungi act as?
Decomposers
Breaks down nonliving organic material
Parasites
Absorbs nutrients from living hosts
Mutualists
Absorbs from a host but reciprocates, like fungi in termites
What are the two most common body structure of fungi?
multicellular filaments- majority of fungi
yeast- single cells
Where do yeast cells live, and how does it get nutrients?
Inhabits moist environments like living tissue
Provides nutrients for said tissues
What do multicellular fungi form, and what does it possess?
hyphae
chitin
What is hyphae, what does it consist of, what is it divided into, and what does it allow?
network of tiny filaments
Consists of tubular cell walls surrounding the cell membrane
Divided into cells by septa (cross-walls)
Allows movement to new territory by growing hyphae
What does chitin do? (3)
strengthens hyphae
enhances absorption
prevents bursting as fungi absorbs water and nutrients through osmosis
What do septa possess?
possesses pores for large molecules to flow from cell to cell
What are coenocytic fungi, what does it consist of, and what does it result from?
fungi lacking septa
Consists of cytoplasmic mass with hundreds of nuclei
Results from repeated nucleic division with no cytokinesis
What is mycelium, and what two things does it do?
interwoven mass of fungal hyphae
Infiltrates the material that fungus feeds on
Increases surface-to-volume ratio to make feeding efficient
What do specialized hyphae allow?
fungi to feed on live animals
What is haustoria?
hyphae used to extract and exchange nutrients with plant hosts
What is mycorrhizae, and what do each side do?
mutalistic relationship between fungi and plant roots
Improves delivery of minerals to plants
Mycelial networks are more efficient than plant roots
Plants provide fungi with organic nutrients
What is ectomycorrhizal fungi?
forms sheaths of hyphae over roots and grow into the extracellular space of the root cortex
What is arbuscular micorrhizal fungi?
extend hyphae through the root cell wall and into tubes formed by invagination of the root cell plasma membrane
Why is mycorrhizae important? (3)
Helps in natural ecosystems and agriculture
Vascular plants rely on fungi for nutrients
Foresters plant seeds with fungi to promote growth
How do fungi reproduce? (4)
Propagate by producing vast numbers of spores
Sexually and asexually
Carried through wind or water
Germinate in moist place with food, producing a new mycelium
During sexual fungi reproduction, are they haploid or diploid?
Fungi nuclei and most spores are haploid
How does sexual fungi reproduction begin?
Begins when hyphae from two mycelia release pheromones- sexual signaling molecules
What happens after fungi release pheromones? (2)
If the mycelia are of different mating types, pheromones bind to one another and hyphae extend towards the pheromones
Hyphae meet and fuse
Why is mating of different mating types important?
contributes to genetic variation and prevents hyphae from fusing with genetically identical mycelium
What is plasmogamy?
union of cytoplasms of two-parent mycelia, which do not fuse right away
What is a heterokaryon?
Parts of the fused mycelium have coexisiting different nuclei
What is karyogamy, what does it undergo, and what does it produce?
haploid nuclei fuse, forming diploid cells
Undergoes meiosis to restore haploid condition
Produces genetically diverse sexual spores
How does asexual fungi reproduction begin?
Grows filamentous fungi producing haploid spores through mitosis
What is mold?
visible mycelia of asexual fungi that grows rapidly
What is a second method of asexual fungi reproduction, and how does it occur?
by growing yeast
Occurs through cell division and pinches of small bud cells off of a parent cell
What are deuteromycetes?
a traditional group of fungi lacking sexual reproduction
What are fungi cloesly related to than others?
animals than plants and other eukaryotes
What did fungi originate from, and what two reasonings support this?
Fungi evolved from a flagellated ancestor
Earliest-diverging lineages have flagella
Protists that share a common ancestor with animals and fungi have flagella
What are opisthokonts, and what does it refer to?
clade of fungi, animals, and protistan relatives
Refers to posterior location of flageullum
What is another trait of fungi ancestors, and what is a supporting reason?
unicellular
Fungi are even more closely related to single-celled protists than animals
What is fungi closely related to?
Nucleariids- amoebas that feed on algae and bacteria
What are animals most closely related to?
choanoflagellates
How did multicellularity evolve in animals and fungi?
independently from different single-celled ancestors
What are chytrids, what genus, what are they also known as, and a characteristic?
first lineage to diverge from the fungal common ancestor
Genus- Rozella
Aka cryptomycota
Have flagellated sperm
When did fungi colonize land?
Fungi colonized land before plants
What is green slime?
mix of cyanobacteria, algae, and variety of small, heterotrophic species like fungi that arrived on land before plants
What did fungi and early land plants do?
formed symbiotic associations with land plants
Fungi transferred nutrients to early land plants which lacked roots
What is the sym gene?
genes on plants which reugire mycorrhizae in order to be expressed
Found in all lineages
What are the five major groups of fungi, and which are paraphyletic?
Chytrids
Paraphyletic
Zygomycetes
Paraphyletic
Glomereomycetes
Ascomycetes
Basidiomycetes
What phylum are chytrids, where are they found, what do they include, and what two things do they possess?
Phylum- Chytridiomycota
Ubiquitous in lakes and soils
Found in hydrothermal vents and other marine communities
Includes decomposers, parasites, and mutualistic species
Possess zoospores- flagellated spores
Have cell walls made of chitin
How are chytrids found?
Found as both single-celled and filamentous
What are examples of parasite and mutualist chytrids?
Parasite example
Contributes to global amphibian decline
Mutalist example
Chytrids living in gut of cattle to break down plants
What phylum are zygomycetes, what do they include, and how do they get nutrition?
Phylum Zygomycota
Includes fast-growing mold that rots food products
Can be parasitic or commensal
How do asexual lifecycle of zygomycetes occur? (4)
Hyphae spreads over food surface, penetrates it, and absorbs
Coenoctic, septa only found where reproductive cells form
Bulbous black sporangia develops at tips of hyphae
Spores develop and disperse, gernminating on moist food
How does sexual lifecycle of zygomycetes occur? (4)
Occurs when environmental conditions deteriorate, like lack of food
Parents of different mating types produce zygosporangium
Resistant to freezing and drying, and are metabolically active
Undergoes meiosis when conditions improve
what are zygosporangium?
sturdy structure in which karyogamy and meiosis occurs
What phylum are glomeromycetes, what were they formerly thought as, and what two things do they form?
Phylum Glomeromycota
Formerly thought to be zygomycetes
Forms arbuscular mycorrhizae
Forms a mutualistic relationship with 80% of plant species
What phylum are ascomycetes, what are they known as, where are the found, and what do they produce?
Phylum Ascomycota
sac fungi
Found in marine, freshwater, and terrestrial habitats
Produces spores (ascospores) in saclike asci
how do ascomycetes get nutrition, what do they live with, and where are they found?
Can act as decomposers, mutualists, and parasites
25% of ascomycete live with green algae or cyanobacteria
Found in mesophyll cells in leaves and can release toxic compounds to protect the plant from insects
How do sexual reproduction of ascomycetes occur? (5)
Ascomycetes develop fruiting bodies called ascocarps containing asci
Conidia fuses with hyphae from a different mating type
After forming a dikaryotic hyphae, it develops into many asci
In each asci, karyogamy occurs, and undergoes meiosis to form four genetically
different nuclei
The nuclei then undergo mitosis, forming eight ascospores
What is conidia?
asexual spores, in large amounts
How does asexual reproduction in ascomycetes occur? (2)
produced conidia- Produced externally in tips of hyphae called conidiophores
Dispersed by wind]
What phylum are basidiomycetes, and how do they get nutrition?
phylum Basidiomycota
Includes mutualists, decomposers, or parasites
Examples of basidiomycete parasites and decomposers
Parasites includes rusts and smut
Decomposers can break down complex polymer lignin
What is a basidium, and what is a club-shaped basidium called?
a cell in which karyogamy occurs, followed immediately by meiosis
Club shaped basidium gives rise to the common name club fungus
What stage in the life cycle is dominant in basidiomycetes, and why?
long-lived dikaryotic mycelium, which allows for more genetic recombination events
What do basidiomycetes produce during their sexual life cycle? (4)
In response to environmental stimuli, mycelium produces fruiting bodies called basidiocarp
Can produce basidiocarps quickly by absorbing water
Can form a fairy ring, or ring of mushrooms
Basidiocarps have caps that support and protect dikaryotic basidia on gills
What occurs during basidiomycete karyogamy? (2)
During karyogamy, two nuclei in baisdium fuse, producing a diploid nucleus
Nucleus undergoes meiosis, which develop into basidiospore
What three roles do fungi have as decomposers?
Can breaks won almost any carbon-containing substrate
Keeps ecosystem stocked with inorganic nutrients essential for plant growth
Unties carbon, nitrogen, and other elements from roganic matter
What are endophytes, and what two things does it do?
fungi that live inside leaves or other plant parts without causing harm
Benefit plants by rpoducing toxins that deter herbivores
Can increase tolerance of heat, drought, or heavy metals
How do fungi form mutualistic relationships with animals?
help animals digest food
Leaf-cutter ants farm these fungi so they can breakdown leaves
What is lichen, what does it grow on, and what is the constituents of lichen?
Symbiotic relationship between a photosynthetic microorganism and fungus
Grows on surfaces of rocks, trees, roofs, and rotting logs
Microorganism can be green algae or cyanobacteria
Fungi is usually an ascomycete, but can also either be glomeromycete or basidiomycete
What is the asexual life cycle of lichen?
Fragmentation or formation of soredia
Soredia- small clusters of hyphae with embedded algae
What does the constituents of lichen do?
Fungus gives the shape and structure, as well as a suitable environment for growth
while the algae occupy the inner layer below the surface and provide carbon compounds.
Cyanobacteria fixes nitrogen and provides organic nitrogen compounds
What are additional things fungi provides for lichen? (2)
Also allows for gas exchange, as well as providing protection and retention of water and minerals
Can also secrete acids with help uptake minerals
Why is lichen important?
breaks down surfaces and allows for plants to grow
how can fungi act as parasites? (4)
Causes loss of about 10-50% fruit harvest
Can produce compounds toxic to humans
Led to extinction of frog and amphibian species
Due to skin infection
Mycosis- infection in an animal by a fungal parasite
What are examples of mycosis?
Skin mycosis- Ringworm, athlete’s foot
Systematic mycoses- spread through the body and causes serious illnesses
From inhaled spores
Ex- yeast infection
How is fungi used practically (6)
used to ripen blue cheese
Can be edible, like truffles
Yeast to produce alcohol beverages, or bake bread
Used in medicine to lower blood pressure, produce antibiotics
Used in basic reseachto study genetics of eukaryotes
Used to produce human glycoproteins
