Chapter 24: Microbial Life, Fungi

Are fungi eukaryotes or prokaryotes?

Eukaryotes, have a nucleus

How do fungi relate more to animals than plants?

chitin in cell walls; heterotrophic; store carbohydrates as glycogen

How do fungi reproduce?

sexually and asexually

Are fungi unicellular or multicellular?

both

How is fungal DNA packaged?

DNA is wrapped around histone proteins

What is the ploidy of most fungal body tissue?

Haploid (n); one set of chromosomes

What structures do fungi contain?

membrane-bound organelles, cell walls; nonmotile

What are fungal cell walls made of?

chitin and glucans

What is chitin?

complex polysaccharide, provides cellular strength

Do fungi have cellular pigments?

Yes; protect against UV light; many are toxic

What are the two morphological stages?

vegetative and reproductive

What is the vegetative stage?

vegetative body produces hyphae; are haploid

What is hyphae?

haploid filamentous structures; individual cells each with single haploid nucleus or large cellular structure with many nuclei

A collection of hyphae is called

mycelium

Individual hyphae cells are divided by

septa

Nondivided hyphae are called

coenocytic hyphae

What is required for fungi to grow?

moist environment; slightly acidic preferred

What are obligate aerobes?

require oxygen to grow

What are obligate anaerobes?

poisoned by oxygen

What are facultative anaerobes?

can survive best with or normally without oxygen

What must fungi consume?

nitrogen; digest before ingested

What are saprophytes?

Microorganisms that live and grow off dead or decaying organic matter; breakdown ligin and cellulose; good ecosystem recyclers

What are three types of asexual fungal reproduction?

Fragmentation, budding, spores

Perfect fungi reproduce how?

both sexually and asexually

Imperfect fungi reproduce how?

only asexually

What is fragmentation?

fragments of hyphae grow into new, separate mycelium

What is budding?

cytoplasm buldges, nucleus divides via mitosis. bud separates

What is spores?

haploid reproductive cell that develops into a haploid vegetative hyphae

What is sporangia?

where spores are produced

What is plasmogamy?

fusion of two unrelated haploid hyphae cells, where nuclei remain separate; heterokaryotic reproductive body (n+n)

What is karyogamy?

fusion of two haploid nuclei to form single diploid zygote; undergoes meiosis to produce haploid spores

What do haploid spores do after being released into environment?

germinate into haploid mycelium

How can mycelium reproduce asexually?

fragment to produce more hyphae or produce haploid spores through mitosis

How does fungi assist in nutrient cycling?

they decompose decaying matter which releases nitrogen and phosphorous, making them available to plants (which they were not availabe before)

What is mutualism?

Symbiotic relationship where both organisms benefit

What is mycorrhizae?

fungi and roots; fungi provided with g3p/glucose, roots assisted with channeling water and dissolved nutrients

What is endophytes?

entire fungus lives inside plant tissue; releases toxins to repel herbivores, chemicals to help plant respond to stress

What is ectomycorrhizae?

hyphae surround the roots like a sheath

What is endomycorrhizae?

hyphae grow inside the roots in structures called arbuscules

What are lichens?

Mutualistic relationship between fungi and photosynthetic algae.

What is the body of a lichen called, and what is it made of?

thallus; fungal hyphae wrapped around algal cells

In a lichen, what does the algae provide to the fungus?

carbon and carbohydrates

In a lichen, what does the fungus provide to the algae?

minerals, protection against desiccation, anchoring to substrate

What is scale insect/fungal mutualism?

fungus provides shelter for tiny insects; insects provide nutrients and spore dispersal

Leafcutter ants farm fungus

ants bring leaves and kill competing fungal species; fungus grows on leaves and digests leaf cellulose

What is parasitism?

one species benefits and the other is harmed

What is haustoria, and what does it do?

hyphae that penetrate tissue of plant by releasing digestive enzymes, causing decay and plant death and toxic buildup

How does fungi affect food?

Causes food spoilage

What is ergot?

disease of cereal crops (wheat, rye) that destroys plant; produces toxic alkaloids like lysergic acid

What is mycosis?

disease caused by fungal hyphae; superficial

What are systemic mycoses?

fungal infections of the internal organs of the body via inhalation of spores

What is mycotoxicosis?

poisoning by a fungal toxin released in food

What is mycetimus?

poisoning due to eating poisonous mushrooms

What are zombie ants?

Fungus infects ants and manipulates brain with toxic chemical to alter behavior (climb spore stalk and fall to infect more ants)

What fungus causes animals to be infected and manipulated?

Ophiocordyceps genus, parasitic fungus

What is Snake Fungal Disease?

caused by the ascomycete Ophidiomyces ophiodiicola: growths on skin/lesions that may cause mortality

What are Batrachochytrium dendrobatidis and salamandervorans?

targets keratin in skin of frogs (BD) and salamanders (BSal); causes lesions/skin peeling and stops breathing; death by asphyxiation