Lecture 4b: Fungi

macroscopic fungi

mushrooms, puffballs

microscopic fungi

molds, yeast

cell wall of fungi

chitin (polysaccharide)

2 types of microscopic fungi cells

hyphae & yeasts

hyphae

long, threadlike cells that make up bodies of filamentous fungi/molds

yeasts

round to oval shape

dimorphic fungi

can grow as a hyphae or yeast depending on conditions like temperature; characteristic of pathogenic fungi (Histoplasma capsulatum)

fungi are heterotrophic

acquire nutrients from a variety of organic substances

fungi are saprobes

live off detritus of dead plants or animals

do fungi require a living host

very few fungi require a living host

mycosis

fungal infection that can occur in plants and animals

macroscopic structure of yeasts

soft, uniform texture and appearance

microscopic structure of yeasts

oval-shaped, single cells that can group together

macroscopic structure of filamentous fungi/molds

cottony, hairy, velvety texture

mycelium

intertwining mass of hyphae; makes up body/colony of mold

septa (septum)

cross walls that divide hyphae; can be solid w/no communication or contain pores w/communication

nonseptate hyphae

one long continuous cell not divided by cross-walls

vegetative hyphae

responsible for mass of growth; used to digest and absorb nutrients

reproductive hyphae

responsible for production of fungal reproductive bodies called spores

budding

asexual (no genetic variation), another cell buds off an existing cell, bud scar remains after new cell separates from existing cell

primary reproductive mode of filamentous fungi

spores

spore function in filamentous fungi reproduction

aid in multiplication, provide genetic variation, dispersion in air, water, living things, will germinate & create new fungal colony after finding favorable substrate

asexual spores

creating more of the same fungi

sexual spores

offer genetic variations that can be potentially advantageous to adaptation and evolution

sporangiospores

formed in a sporangium, attached to a stalk; spores are released when sporangium ruptures

condiospores

free spores; develop by pinching off tip of special fertile hypha or segmentation of preexisting vegetative hyphae (most common, occur in multiple forms including arthospores and microconidia)

process of sexual spore formation

fusion of fertile hyphae of two different strains to a complex union of differentiated male and female structures and development of special fruiting bodies (genetic variation)

3 most common sexual spores

zygospores, ascospores, basidiospores