Chapter 31: Fungi Flashcards
What supergroup and subgroup are fungi in?
Unikonta
- Opisthokonts
True or False:
Fungi are autotrophs
False, they are heterotrophs
Meaning they feed on organic matter produced by other organisms
List characteristics of the kingdom Fungi
- Have a cell wall composed of chitin
- Single/multicellular
- Chemoorganotrophs
- Dispersed by means of spores
- Bodies are constructed or hyphae
What are some important ecological roles of fungi?
- Decomposers
- Mutualists
- form mycorrhizal associations with 80% of plants
- Pathogens
What is hyphae?
The individual filaments that make up the body of a mycelium
What are the two types of fungi?
- Single-celled
- yeasts
- Multicellular filaments
- mycelia
What is mycelium?
The root looking part of a fungus (the underground part)
- web of hyphae
How do fungi eat?
Their hyphal tips secrete enzymes that break down the substrate and absorb it
- products diffuse back into hyphae - fungi grows through its food
What enhances feeding by absorption for fungi?
Chitin in their cell walls
What other features do fungi have that aid in food absorption?
- Large surface area/volume
- Ability to break down cellulose and lignin
During absorptive feeding, what role does the nucleus play?
The nucleus hangs back (stays away from the very tip of the hyphae) and directs the movement
How does a large surface area aid in absorptive feeding?
It’s easier for food to get through a larger surface area of skin
Digestion and absorption for fungi occurs _________.
extracellularly (occurs outside of the cell)
What are the two forms of hyphae and what are their differences?
- Septate hypha
- hyphae are divided into cells by septa
- the septa have pores for nutrients and organelles to flow from cell to cell
- Coenocytic hypha
- hyphae have no dividing walls
- thousands of nuclei
Mycelia are the ________ ______ ________ of fungi
ecologically active bodies
Are mycelia rigid or elastic?
Both, they are mostly rigid but their tips are elastic so that they can stretch to find food
True or False:
Mycelia have a huge surface area
True
What is the mushroom?
A fruiting body for reproduction
How many spores make up a mycelium?
One, an entire web of mycelium grows from one spore
Fungi are saprophytes. What does saprophyte mean?
An organism that feeds on dead or decaying matter
Fungi are symbionts. What does symbiont mean?
A mutually beneficial relationship between a fungus and another organism
What are mycorrhizal associations?
Symbiotic relationship between a fungus and a plant’s roots
Fungi are parasites. What does parasite mean?
An organism that feeds on the living tissue of a host
Parasites that cause disease are called ________.
pathogens
What is enzyme induction?
When fungi only produce digestive enzymes that are required for the substrate they’re trying to absorb
How do fungi absorb their food if ammonia and glutamine are present in the environment?
Fungal enzymes usually take up nitrates and turn them into ammonia to use.
However, if ammonia and glutamine are already present in the environment, they repress the fungal enzymes and the fungi uses them instead to aid in absorption.
How do fungi absorb their food if glucose is present in the environment?
Fungal enzymes usually absorb sucrose, maltose and galactose.
However, if glucose is already present in the environment it will repress the fungal enzymes and the fungi just uses glucose instead.
Explain how some fungi are predators
Some fungi have hyphae that are adapted for trapping prey.
For example, there is a fungi who’s hyphae forms hoops that trap nematodes and the fungi slowly breaks them down and absorbs them.
What are haustoria?
Specialized hyphae that fungi use to extract or exchange nutrients with their plant host
Explain the asexual life cycle of fungi
- Mycelia produce a spore-producing structure (mushroom)
- Spore-producing structure produces spores
- Spores germinate (grow and develop) into a new mycelium
Explain the sexual life cycle of a fungi.
- A hyphae (n) from one mycelium fuses with the hyphae (n) of another mycelium
- Plasmogamy occurs - cytoplasms of mycelia unite
- nuclei from each mycelia do not fuse right away (heterokaryotic stage)
- Karyogamy occurs - the haploid nuclei fuse and zygotes (2n) form
- Meiosis occurs and haploid spores are produced
- Spores germinate (grow and develop) into a new mycelium
Fungi are hypothesized to have ________, _____________ ancestors.
unicellular, flagellated
What are the 5 phyla of fungi?
- Chytridiomycota
- Zygomycota
- Glomeromycota
- Ascomycota
- Basidiomycota
What are characteristics of the phylum chytridiomycota (chitrids)?
- “simple” fungi
- found in freshwater/terrestrial habitats
- ONLY fungi to have flagellated spores called zoospores
- they are decomposers, parasites and mutualists
- diverged early in fungal evolution
What are the characteristics of the phyla zygomycota?
- fast growing molds, parasites and commensalism symbionts
- mostly have coenocytic hyphae
- have sexually produced zygosporangia
- zygosporangja are resistant to freezing and drying
(Grow on fruits and bread!)
What are the characteristics of the phyla glomeromycota?
- tiny group
- form intracellular associations (penetrate) with plant roots called arbuscular mycorrhizae
- cannot survive without a host
- no sexual reproduction
(Dwarf mycorrhizae that latches into a host)
What are the characteristics of the phyla ascomycota?
- “Sac fungi”
- bread yeasts, molds, cup fungi, truffles, morels
- serious plant pathogens> have ascocarps that have ascus that produce spores
What are the characteristics of phyla basidiomycota (club fungi)?
- long lived dikaryotic mycelium
- mushrooms, puffballs, mutualists, plant parasites
- enzymes decompose wood, leaves etc
- they are decomposes, pathogens, an form mycorrhizal associations with plants
Explain the sexual life cycle of Phylum Chytridiomycota.
- Two separate hyphae fuse and form a diploid zygote
- Diploid zygote grows and produces haploid zoospores
- Zoospores develop into new mycelia
Explain the asexual life cycle of Phylum Chrytridiomycota.
- Sporangia produce flagellated zoospores
2. Zoospores will swim to a new pollen grain and develop into new mycelia
What is a zygosporangium?
Sporangia for zygomycetes
Define plasmogamy
When the cytoplasms of mycelia unite
- their nuclei do not fuse right away (n)
(Heterokaryotic stage)
Define karyogamy
Haploid nuclei of united hyphae fuse and zygotes (2n) form
What is a basidiocarp?
The mushroom
What is a basidium?
Club shaped reproductive structure that holds 4 basidiospores
Explain the sexual life cycle of Phylum Zygomycota.
- Neighboring mycelia of different mating types (+/-) form hyphal extensions containing several haploid nuclei
- Plasmogamy occurs
- cytoplasms of mycelia unite
- nuclei do not fuse right away (n) (heterokaryotic stage)
- zygosporangium (w/ rough wall) forms
- Karyogamy occurs - the haploid nuclei fuse and zygotes (2n) form
- Meiosis occurs and the zygosporangium (n) germinate into a sporangium on a short stalk
- Sporangia disperse haploid spores that germinate and grow into new mycelia
Explain the asexual life cycle of Phylum Glomeromycota.
- Sporangia at hyphae tips release asexual spores that germinate and grow
Explain the asexual life cycle of Phylum Zygomycota.
The sporangia on short stalks sticking out of the zygosporangia produce genetically identical spores
What is an ascus?
Spore-producing saclike structure
What are ascocarps?
Fruiting bodies for ascomycetes where ascospores are made
Explain the sexual life cycle of Phylum Ascomycota.
- Mycelia produce specialized hyphae, which conidia (asexual spores) fuse to.
- Plasmogamy occurs
- cytoplasms of mycelia unite
- nuclei do not fuse right away (dikaryotic stage)
- hyphae (2n) produce many asci (2n)
- Karyogamy occurs
- the haploid nuclei fuse and zygotes (2n) form
- Meiosis occurs and 4 haploid nuclei are yielded within one ascus, which then proceeds to mitosis where 8 haploid nuclei are yielded within one ascus
- The 8 haploid nuclei develop into ascospores
- The ascospores disperse through an opening in the ascocarp and give rise to new mycelia
What are conidia?
Asexual spores produced by ascomycetes for asexual reproduction
Explain the asexual life cycle of Phylum Ascomycota.
Mycelium develop conidiophores that disperse conidia, which germinate and grow into new mycelia.
Explain the sexual life cycle of Phylum Basidiomycota?
- Two haploid mycelia of different types (+/-) undergo plasmogamy
- New mycelium forms and gives rise to mushrooms (basidiocarps) as a result of environmental stress
- Karyogamy occurs
- in the gills of the mushroom, there are cells called basidia that produce a diploid nucleus
- Each diploid nucleus yields 4 haploid nuclei per basidium, which develop into basidiospores
- The basidiospores disperse by the wind when they are mature and germinate into new mycelia
What type of hyphae do Phylum Chytridiomycota have?
Coenocytic hyphae
What is the umbrella part of the mushroom called?
Pileus
What type of hyphae do Phylum Zygomycota have?
Mostly coenocytic hyphae
Some septate hyphae
What type of hyphae do Phylum Ascomycota have?
Septate hyphae
What type of hyphae do Phylum Basidiomycota have?
Septate hyphae
Which phylum of fungi does not reproduce asexually?
Phylum Basidiomycota
Which phylum of fungi does not reproduce sexually?
Phylum Glomeromycota
Which phylum do yeasts belong to?
Phylum Ascomycota
Do yeasts produce sexually or asexually?
Asexually by budding
What do yeasts do?
Breakdown glucose into ethanol and CO2
How do fungi live as mutualists with plants?
They live as endophytes (usually ascomycetes)
- live inside plant parts without causing harm
How do fungi live as mutualists with animals?
They form fungus-animal symbioses
- the fungi will help ants break down their food and kill harmful substances within their food
- the ants will feed off of the food-enriched hyphae tips of the fungus
Fungi form beneficial relationships with plants roots, what is this fungi called?
Mycorrhizae
There are two types of Mycorrhizal fungi, what are they and how do they differ?
- Arbuscular mycorrhizal
- hyphae penetrate root cell wall but not plant membrane
- most common
- partners with ascomycetes
- no fruiting bodies
- Ectomycorrhizal
- hyphae do not penetrate root cell wall, only surround it
- less common
- partners with basidiomycetes (most hosts are trees)
- have fruiting bodies
What is a lichen?
A symbiotic association (organism) between a fungus and a photosynthetic organism
What are the three types of lichens?
- Crustose lichens
- flag crusty plates
- Foliose lichens
- leafy, lobed, or branches structures
- Fruticose lichens
- thin, tiny shrubs: beardlike appearance
What type of hyphae do Phylum Glomeromycota have?
Mostly coenocytic hyphae
