Kingdom Fungi Flashcards
How do fungi eat?
They are heterotrophs and absorb nutrients from outside their bodies
How do fungi digest?
They use hydrolytic enzymes to break molecules down and can digest compounds from many sources, living or dead
What three major roles do fungi exhibit in the ecosystem?
Decomposers, parasitic, and mutualistic
Decomposer Fungi
Break down and absorb nutrients from nonliving organic material
Parasitic Fungi
Absorb nutrients from living hosts
Mutualistic Fungi
Absorb nutrients from hosts and reciprocate with actions that benefit the host
What are the most common morphology of fungi?
Multicellular filaments and single cells (yeasts)
Mycelium
Fungal body made up of hyphae that infiltrates the food source. Its structure maximizes surface-to-volume ratio, making absorption very efficient
Hyphae
Tiny filaments with tubular cell walls strengthened with chitin
What does chitin do for cells?
It’s a structural polymer that prevents cells from lysing due to osmotic pressure from nutrient absorption
How are hyphae divided most of the time?
They are divided into cells by cross walls called septa (septa have pores large enough to enable cell-to-cell movement of organelles)
What is different with the hyphae in coenocytic fungi?
They lack septa, and have hundreds or thousands of nuclei in a continuous cytoplasmic mass
Do hyphae grow in length or girth?
Length
Cytoplasmic Streaming
Since hyphae grow in length, this is the process they use to move materials to the tips
How do multicellular fungi colonize?
They aren’t motile but they colonize new territory through hyphae growth
Haustoria
Specialized hyphae that let fungi extract nutrients from plants
Arbuscules
Specialized hyphae that penetrate plant cell walls but not the cell membrane (used by mutualistic fungi)
Mycorrhizae
Means “fungus roots”
Mutually beneficial relationship between fungi and plant roots
Mycorrhizal fungi deliver phosphate ions and minerals to the plants, and plants supply organic nutrients to the fungi
What do phosphate ions and minerals from mycorrhizal fungi do for plants?
Increases the amount of surface area for absorption and may provide protection against pathogens
What are the two main types of mycorrhizal fungi?
Ectomycorrhizal and arbuscular
Ectomycorrhizal Fungi
Form sheaths of hyphae over the root surface and extend into the extracellular spaces of the root cortex
Arbuscular Mycorrhizal Fungi
Extend arbuscules through the root cell wall and into tubes formed by invagination of the root cell plasma membrane
What types of plants are involved in mycorrhizal relationships?
Vascular plants
How do mycorrhizal fungi colonize soils?
Dispersal of haploid cells called spores
Does fungal reproduction occur sexually or asexually?
Both
Are fungal nuclei and spores diploid or haploid?
Usually haploid, although some species have diploid nuclei formed during sexual life cycles
What does sexual reproduction in fungi require?
Fusion of hyphae from different mating types
How do fungi signal which mating type they are?
By using pheromones (sexual signaling molecules)
Plasmogamy
The union of cytoplasm from two parent mycelia
Heterokaryon
A mycelium that contains coexisting, genetically different nuclei (during reproduction)
Dikaryotic
When haploid nuclei in some fungi pair off two to a cell–mycelium is called dikaryotic
Karyogamy
The fusion of nuclei–a process that could take hours, days, or even centuries
What leads to genetic variation in fungi?
The paired processes of karyogamy and meiosis
Molds
A type of fungi that produces haploid spores asexually by mitosis, forming visible “furry” mycelia
How do single-celled yeasts reproduce?
Asexually without producing spores; it occurs through simple cell division called “budding”
Deuteromycetes
A group of fungi (including yeasts and filamentous fungi) that have no known sexual stage
What group is fungi most closely related to?
Fungi and animals are more closely related than either group is to plants or most other eukaryotes
What was the ancestor of fungi?
An aquatic, single-celled, flagellated protist
What was required for mycorrhizal formation?
Sym genes
Cryptomycetes and Microsporidians
Phylum Cryptomycota and Phylum microsporidia form a sister group; basal fungal lineage
Phylum Cryptomycota (Cryptomycetes)
Only 30 known species, but are a large and diverse group. They are found in soils, marine, and freshwater. There are aerobic and anaerobic species, and many species are parasites of protists and other fungi.
Cryptomycetes are unicellular and have flagellated spores. (also can synthesize chitin-rich cell wall)
Phylum Microsporidia (Microsporidians)
-Known species are unicellular parasites of protists and animals
-Can synthesize chitin-rich cell wall
-Highly reduced mitochondria and small genomes
-Spores infect host cells with harpoon-like organelle
Phylum Chytridiomycota (Chytrids)
-1000 known species
-Found in lakes, soil, and marine habitats
-Include species functioning as decomposers, parasites, and mutualists
-Most have flagellated spores called zoospores
-Chitin cell walls
-Some single-celled, others form colonies
Phylum Zoopagomycota (Zoopagomycetes)
-900 known species
-Live as parasites or commensal symbionts of animals, or as parasites of other fungi or protists
-Form filamentous hyphae and reproduce asexually via nonflagellated spores
-Some induce behavioral changes in insects they parasitize
-Those that reproduce sexually form structure called zygosporangium
-Non-flagellated wind dispersed spores
Zygosporangium
Structure formed by Zygomycetes and some Mucoromycetes, houses and protects zygote
What types of fungi exist in Phylum Mucoromycota (mucoromycetes)?
Important decomposers (Rhizopus stolonifer–bread mold), also parasites, pathogens, or mutualists with plants (some mycorrhizae)
Describe the mucoromycete life cycle.
-Plasmogamy produces a zygosporangium
-Karyogamy and then meiosis occur within that zygosporangium
-Coenocytic hyphae spread and penetrate surface (absorb nutrients from rotting food)
-Sporangia develop at tips of upright hyphae, asexually producing genetically diverse sporses
What’s special about zygosporangia?
They are metabolically inactive and resistant to freezing and drying
Glomeromycetes
An arbuscular-forming clade of fungi in the Phylum Mucoromycota
–most plant species have mutualistic partnerships with arbuscular mycorrhizae
Ascomycetes
Phylum Ascomycota, known as “sac fungi”
Live in marine, freshwater, and terrestrial
Where did ascomycetes get their nickname?
Called sac fungi because of the saclike asci where their spores are produced
What do ascomycetes produce during the sexual stage?
Fruiting bodies called ascocarps that contain spore-forming asci
What types of fungi are included in the phylum Ascomycota (ascomycetes)?
Plant pathogens, decomposers, and symbionts
More than 25% form lichens, symbiotic associations with green algae or cyanobacteria
Some form mycorrhizae with plants
How do ascomycetes reproduce asexually?
By enormous numbers of asexual spores called conidia
Where are conidia produced?
At the tips of specialized hyphae called conidiophores
How do ascomycetes reproduce sexually?
Conidia fuse with hyphae of mycelium from different mating type, forming dikaryotic cells (each containing 2 haploid nuclei, one from each parent). Asci form at tips of dikaryotic hyphae, and karyogamy and meiosis occur there. Ascospores develop and are discharged from the ascocarp
What types of fungi are included in Phylum Basidiomycota (basidiomycetes)?
Some are mutualists that form mycorrhizae, while others are destructive plant parasites (rusts and smuts)
MUSHROOMS
What is Phylum Basidiomycota named for?
The basidium; a cell where karyogamy and meiosis occur
Where did the name club fungus come from?
The basidium’s club-like shape
What do basidiomycetes do?
They are important decomposers of wood, and certain ones are best at decomposing lignin (a complex polymer abundant in wood)
How do basidiomycetes reproduce sexually?
They produce fruiting bodies called basidiocarps (white mushrooms in stores)
How does a mushroom form?
It results from a concentrated growth of hyphae from the dikaryotic mycelium. The cap supports and protects a large surface area of dikaryotic basidia on gills. Karyogamy occurs within the basidia, then meiosis, and sexually produced basidiospores are ejected and dispersed by wind
Endophytes
Fungi or bacteria that live inside leaves or other plant parts without causing harm (most are ascomycetes)
Lichens
Symbiotic associations between photosynthetic microorganisms and fungi (grow on rocks, rotting logs, trees, and roofs)
-Fungal partners usually ascomycetes
-Photosynthetic partners usually unicellular or filamentous green algae or cyanobacteria
How do lichens reproduce?
Asexually by fragmentation or formation of soredia
Soredia
Small clusters of hyphae with embedded algae
What is the function of lichen?
They physically penetrate the surface and break it down chemically, some also fix nitrogen
Mycosis
General term for fungal infection in animals; such as ringworm which causes athlete’s foot. Treated with fungicidal lotions and powders
Coccidioidomycosis
Potentially fatal mycosis that produces tuberculosis-like symptoms in lungs, lives in soil in SW US and parts of Mexico and Central & South Ameria
Acquired by inhaling spores
Distinguishing features of Cryptomycota
Parasites with flagellated spores
Distinguishing features of Microsporida
Parasitic cells that form resistant spores
Distinguishing features of Chytridiomycota
Flagellated spores
Distinguishing features of Zoopagomycota
Resistant zygosporangium as sexual stage
Distinguishing features of Mucuromycota
Include fungi that form arbuscular mycorrhizae with plants
Distinguishing features of Ascomycota
Sexual spores (ascospores) borne internally in sacs called asci; vast numbers of asexual spores (conidia) produced
Distinguishing features of Basidiomycota
Elaborate fruiting body (basidiocarp) containing many basidia that produce sexual spores (basidiospores)
