Mycology Midterm 1

What are fungi?

Fungi are eukaryotic organisms in Kingdom Fungi, a monophyletic group that diverged from a common ancestor with animals about 1 billion years ago

Are fungi plants or animals?

No. Fungi are neither plants nor animals, but they are more closely related to animals

What is a mushroom?

A mushroom is the reproductive (fruiting) body of a fungus that produces spores

What is mycelium?

Mycelium is the main body of a fungus, consisting of a network of hyphae

How many species of fungi are there?

bout 100,000 species are described, but 5.1–8 million species are estimated to exist

Why are fungi considered underdescribed?

Only a small fraction of fungal diversity has been formally identified and studied

How are fungi important in everyday life?

Fungi provide food, medicines, fermented products, industrial materials, and ecological services

What role do fungi play in baking and brewing?

Yeast (Saccharomyces cerevisiae) ferments sugars to produce carbon dioxide and alcohol

How do fungi make cheese?

Penicillium species create flavors and textures in cheeses like blue cheese and camembert

What are examples of fungal food products?

Kombucha, soy sauce, miso, tempeh, Quorn, cheese, and meat substitutes

Why are fungi important sources of drugs?

Fungi produce antibiotics and other medically important compounds

Why are fungi important plant symbionts?

Mycorrhizal fungi associate with about 90% of terrestrial plants and enhance nutrient uptake

How do fungi cause disease in plants and animals?

Some fungi act as pathogens, infecting tissues and disrupting normal biological processes

How do fungi affect humans negatively?

They can cause infections, allergies, and illness, especially in water-damaged buildings

What does it mean that fungi can create “zombies”?

Certain fungi manipulate host behavior, such as Ophiocordyceps controlling ants

What are the three domains of life?

Bacteria, Archaea, and Eukarya; fungi belong to the domain Eukarya

What is a fungus (lowercase f) versus a Fungus (capital F)?

A fungus refers broadly to organisms studied by mycologists, while a Fungus is a member of the monophyletic kingdom Fungi

What general traits define fungi?

They are eukaryotic, heterotrophic, spore-forming organisms that are often filamentous and primarily microscopic with macroscopic stages

What is syngamy?

Syngamy is the fusion of two compatible cells during sexual reproduction

What is karyogamy?

Karyogamy is the fusion of two nuclei following syngamy, producing a diploid nucleus

What is meiosis?

Meiosis is a specialized cell division that reduces chromosome number by half, producing four genetically distinct haploid cells

How are syngamy, karyogamy, and meiosis arranged in fungal life cycles?

These processes are often temporally separated, with long haploid or dikaryotic stages between them

In what forms can fungi exist?

Fungi can be unicellular (yeasts) or filamentous, consisting of hyphae that form a mycelium

What are hyphae?

Hyphae are tubular, filamentous cells that grow at their tips and make up the fungal body

What are the key features of hyphae?

They grow at the tip, grow into food, secrete enzymes, digest polymers, and absorb monomers

How do fungi obtain nutrients?

Fungi are heterotrophic and feed by absorption after extracellular digestion of organic material

What are fungal cell walls made of?

Cell walls contain chitin, while cell membranes contain the sterol ergosterol

Why is ergosterol important in fungi?

Ergosterol maintains membrane structure and function and is unique to fungi

Why do many antifungal drugs target ergosterol?

Disrupting ergosterol damages fungal membranes without affecting animal cells, which lack ergosterol

What is the AAA (not DAP) lysine pathway?

A fungal-specific lysine biosynthesis pathway distinct from the DAP pathway found in plants and bacteria

Why is the AAA lysine pathway useful in mycology?

It serves as an evolutionary marker distinguishing fungi from other organisms.

What type of mitochondria do fungi have?

Fungal mitochondria have plate-like cristae and gene content similar to animals but with more introns

What is the typical nuclear state of fungi?

Fungal nuclei are haploid for most of the life cycle, except during brief diploid stages

How do fungal zoospores differ from oomycete zoospores?

Fungal zoospores have a single posterior whiplash flagellum, while oomycetes usually have two flagella

What are vegetative features of fungi?

They include hyphae, mycelia, yeasts, plasmodia, slugs, and zoospores

What is a mycelium?

A mycelium is an interconnected network of hyphae that functions as the main vegetative body

What are key features of mycelium?

Anastomosis, efficient nutrient foraging, long-distance transport, and coordinated growth behavior

What are rhizomorphs?

Thick, cord-like fungal structures specialized for long-distance nutrient and water transport

What is vegetative compatibility in fungi?

A genetic recognition system determining whether hyphae can fuse and share resources

Why is anastomosis considered sex in fungi?

Hyphal fusion can involve mating-type loci and determines whether genetic exchange is allowed

What are the major fungal life cycle types?

Haploid-dominant, dikaryotic-dominant (Basidiomycota), and diploid-dominant

What is the scientific classification hierarchy for fungi?

Kingdom → Phylum → Class → Order → Family → Genus → Species

What are saprobic fungi, and give three examples of their roles?

Saprobes decompose dead organic matter, break down cellulose and lignin, recycle nutrients, and drive soil carbon cycling

What are symbiotic parasitic fungi, and give three examples of their roles?

They infect plants, animals, or other fungi, cause disease, extract nutrients from hosts, and reduce host fitness

What are symbiotic mutualistic fungi, and give three examples of their roles?

Mutualists form lichens, mycorrhizae, and animal symbioses, benefiting both partners through nutrient exchange and protection

What are symbiotic commensal fungi, and give three examples of their roles?

Commensals such as endophytes live within hosts, gain shelter or nutrients, and typically cause no harm

What are zoosporic fungi?

Fungi characterized by the production of motile zoospores with flagella

What feature defines fungi characterized by zoospores?

They produce swimming spores, typically with a single posterior flagellum

What is meant by zoosporic diversity?

The wide variation in zoospore structure, flagella number, and life histories among early-diverging fungal lineages

What are Microsporidia?

Obligate intracellular parasites of animals with extremely reduced genomes and remnant mitochondria

What disease is caused by Nosema species?

Nosema bee disease, which negatively affects honeybee health and colonies

What is Cryptomycota and why are they called “hidden fungi”?

A fungal phylum lacking a chitin-rich cell wall during observed life stages and known mostly from environmental DNA

What is Rozella and why is it important?

A genus within Cryptomycota that provides insight into early fungal evolution and parasitism

What is Rozella allomycis?

An intracellular parasite of the Blastocladiomycota fungus Allomyces

What are zoosporangia?

Sporangia that produce motile zoospores for dispersal

What are resistant sporangia?

Thick-walled sporangia that allow fungi to survive harsh conditions after host death

What defines Blastocladiomycota?

Zoosporic fungi with single posterior flagella and true alternation of generations

What ecological roles do Blastocladiomycota play?

They may be saprobes or parasites of plants and animals

What defines Chytridiomycota?

Primarily aquatic fungi with unicellular thalli that produce zoospores

What structures do chytrids use to anchor and absorb nutrients?

Rhizoids, which are anucleate hyphae-like structures

What is Batrachochytrium dendrobatidis (Bd)?

A chytrid fungus responsible for global amphibian population declines

How does Chytridiomycota–Bd infect amphibians?

Zoospores penetrate skin, encyst, and develop into sporangia that release new zoospores

What is Neocallimastigomycota (Neocallimastigomycetes)?

Anaerobic gut fungi living in ruminants that efficiently degrade plant biomass

What is unique about Neocallimastigomycota genomes?

They show extensive horizontal gene transfer from bacteria, plants, and animals

What characterizes zygomycete fungi?

They produce thick-walled sexual zygosporangia and lack flagellated spores

Which phyla are included in zygomycete fungi?

Zoopagomycota and Mucoromycota

What does zygomycete diversity represent evolutionarily?

The transition to terrestrial, filamentous fungi and loss of the fungal flagellum

What clade includes Entomophthoromycotina, Zoopagomycotina, and Kickxellomycotina?

The Zoopagomycota

What defines Zoopagomycotina?

Primarily parasites of animals or other fungi, often forming haustoria

What trapping strategy is used by some Zoopagomycotina fungi?

Adhesive hyphal traps (“lethal lollipops”) to capture small animals

What defines Kickxellomycotina?

A group with diverse ecologies including insect gut associates, fungal parasites, and soil saprobes

What defines Entomophthoromycotina?

Insect-parasitic fungi that manipulate host behavior to enhance spore dispersal

What clade includes Glomeromycotina, Mortierellomycotina, and Mucoromycotina?

The Mucoromycota

What are Glomeromycotina and arbuscular mycorrhizal fungi (AMF)?

Mutualistic fungi that associate with plant roots to exchange nutrients for carbon

Why are AMF biologically unusual?

AMF can carry thousands of nuclei within their spores and hyphae

What are Mortierellomycotina and Mucoromycotina known for?

Mortierellomycotina are common soil and root-associated fungi, while Mucoromycotina include fast-growing saprobes like Rhizopus and Phycomyces

Do most fungi form mushrooms?

No. About 90% of fungi do not form macroscopic fruiting bodies (mushrooms)

Which fungi commonly form mushrooms?

Some fungi in the Dikarya, mainly Basidiomycota and Ascomycota, form mushrooms when environmental conditions are favorable

What are Basidiomycetes?

Fungi that produce spores on basidia; most familiar gilled mushrooms belong to this group

What are Ascomycetes?

Fungi that produce spores in asci, which are microscopic sac-like structures

Key feature of the Basidiomycete life cycle

Includes a dikaryotic mycelium stage, followed by nuclear fusion (syngamy), meiosis, and spore production on basidia

How do mushrooms develop?

Many mushrooms develop from egg-like structures, with partial and universal veils that leave rings and volvas as remnants

What are mushrooms made of?

Mushrooms are composed entirely of tightly packed hyphae

What is an agaric?

An agaric is a gilled mushroom with a cap, gills, and a stem

Main anatomical parts of gilled mushrooms

Cap (pileus), gills (lamellae), stem (stipe), ring (annulus), cup (volva), and surface scales or warts

What does diversity in mushroom morphology mean?

Mushrooms show wide variation in form, including gills, pores, teeth, jelly-like bodies, and enclosed fruiting structures

Macroscopic characteristics used in mushroom identification

Cap shape, gill attachment, stalk shape and position, texture, color, and growth habit

Microscopic characteristics used in mushroom identification

Spore size, shape, ornamentation, color, and chemical reactions with stains or reagents

What is a spore print and why is it useful?

A spore print shows spore color, which is an important trait for narrowing down identification

Laccaria – key identifying features

A gilled mushroom with widely spaced gills and white spores that are spiny under the microscope

Pisolithus – key identifying features

A puffball or earthstar-type fungus with brown, hairy spores, often found in disturbed soils

Ganoderma – key identifying features

A wood-growing polypore or bracket fungus with brown, pitted spores

Russula and Lactarius – key identifying features

Gilled mushrooms with white spores that are amyloid and turn blue-black in Melzer’s reagent; Lactarius species often exude milky latex

Rhodocollybia butyracea – key identifying features

A gilled mushroom with dextrinoid spores that turn reddish-brown in Melzer’s reagent

Entoloma and Tomentella – key identifying features

Entoloma has pink gills and angular pink spores, while Tomentella is a brown crust fungus with asteroid-shaped spores

What is Dikarya?

Dikarya is a fungal clade that includes Ascomycota and Basidiomycota and is defined by having a dikaryotic (n+n) stage in the life cycle

What does monokaryotic or homokaryotic mean?

A hyphal compartment that contains one or more nuclei of the same genotype

What does dikaryotic or heterokaryotic mean?

A hyphal compartment that contains two genetically distinct nuclei sharing the same cytoplasm

What is Ascomycota?

Ascomycota is a major fungal phylum characterized by the production of sexual spores inside asci

What types of organisms are included in Ascomycota?

Ascomycota include filamentous fungi, yeasts, lichens, plant pathogens, and mushroom-forming species