ah ze fungiiiiiiiiii Flashcards
what part of the fungi lies underneath the soil?
the mycelium
3 ways in which fungo are like animals
not producers
no photosynthesis
chitin not cellulose e.g. like insects
3 ways in which fungi are like plants
grow on a substrate
non motile
cell walls
which other group is fungi closest to?
animals
how many described species of fungi are there, and how many are estimated
100,000
estimated 0.8 to 5.1 million
which continent has fewer fungi than others and why
africa
soil acidity
why is there a positive correlation between fungi abundance and annual precipitatoin
mycelium cannot prevent water loss
show the diversity of fungal size
smallest e.g. yeast - 3-4ym long
armellaria ostoyae - honey fungi worlds largest organism
4 square miles large
describe saprotrophs
get energy from already dead material many have fruiting bodies
describe symbionts
interact with plant rooting sytem
desccribe how symbionts increase nutrtient uptake
release enzymes into the soil that alter the pH
have many specific nutrient transporters
what % of plants dont have mycorrhizae
90%
what percentage of crop plants are lost to fugal pathogens , how many people could this feed?
8-10%
feed 600 million
why would it be catastrophiv if we had no more saprotrophic fungi?
without them we would get an acuumulation of plant remains nutrinets would be bound up and soil depleted of atmospheric CO2 for photosynthesis
describe breifly the growth pattern of fungal growth
spore - dormant
hyphae - long branching filamentous structure
mycelium - collective name for mass of hyphae derived from one spore
hyphae can take up ______ quickly but lose ______ quickly
nutrients
water
_________ fungi form hyphae
filamentous
what is different about oomycetes and fungi
oomyects have cellulose as well as chitin
describe the layers of the fungal cell wall
inner most layer - chitin and proteins
protein layer
reticulum - proteins and glucans
outer layer glucans
functions of the fungal cell wall
maintain cell shape barrier to the external world molecular sieve cellular protection antigenic properties
fungal hyphae always grow from the ____. here the cytoplasm is _____ and their are more ________
Tip
denser
mitochondria
where does digestion occur in fungi
hyphal tips
fungi are heterotrophic what does this mean
acquire external sources of food
fungi excrete enzymes to perform __________ digestion.
extracellular digestion
describe the process of extra cellular digestion
vesicles fuse with plasma membrane and release digestive enzymes and cell compents
digestive enzymes bream down extra cellular proteins a d small organic molecules
organic molecules are taken into hyphal via plasma membrane transporter proteins
higher solute concentration in hypha causes water uptake via osmosis
as a result cells enlarge and hyphal tip extends new cell wall materials are added to cell wall
desscribe the following zones of fungi
- extension
- productive
- fruiting
- aged
extension - digestion and excretion
productive zone - fungal colonny produces reproductive structures
fruiting zone = initation of fruting zone
aged zone = hyphae become vaculated and empty - autolysis occurs
define homothalic
mate with themselves
define heterothalic
heterothalic only isolates of oppsoite mating type can mate
why did anisogamy species used to be named twice?
male and female parts look different
four larger groups of fungi
higher fungi - ascomycota and basidiomycota - have sperate hyphae
zygomycota - non seperate hyphae one long cell with several nuclei
imperfect fungi - no sexual stage known
describe basidiomycota, how many species?
club fungi
fruiting body = mushroom
31,500 described species
fungi can get so large because their growth is _______
indeterminate
describe the basidium
microscopic spore producing structure - basidia presence is charcteristic of basidomycota
forms basdidia from which spores form
describe the reproduction of basiodomycota, stating wether diploid dikaryotric or haploid at each stage
1) spores land and germinate - haploid
2) hyphal union - hyphale fuse and plasmogamy occurs - dikaryotic
3) fruiting body forms - develops above ground gills lined with hymenium still dikaryotic
4) karyogamy - fusion of haploid nuclei in the basidium becomes diploid - 2n
5) meiosis occurs to form basidiospores - released and are haploid
are spores toxic?
no, its metabolites within the mushroom that are toxic
what is the largest phyla of fungi and how many are there
ascomycota
64,000 species
define the ascus
microscopic sac like sexual structure where the spores are formed
desribe the life cycle of a ascomycota
1) formation of gametangia = sexual structures formed from thin hyphae = trichogyne - ascogonium and antheridium
2) nuclei migrate towards the ascogonium, forms a dikaryotic mycelium from which an ascocarp forms (fruiting body)
3) hymenium forms from ascocarp, tissue layer where the cell develop into asci in the bottom of the cup
4) karyogamy occurs - fusion of two haploid nuclei in the ascus followed by meiosis and mitosis
describe zygomycota
molds symbionts and pathogens
small phylum 1050 described species
describe the sex of zygomycota
hyphae of oppsoite mating types grow side by side
tips develop into gametangia which produce gametes
gametangia and gametes fuse
resulting zygote develops into a resistant zygospore via plasogamy
all haploid up till this point
fertilises itself - karyogamy into a diploid multinucleate zygospore with zygosporangium
define plasmogamy and karyogamy
plasmogamy = fusion of two hyphae
karyogamy = fertilisation
why does wood pose a porblem to fungi and how do they overcome it? what is the brown rot fungi method
OH groups in lignin causes tight bonds to cellulose and hemicellulose
forming a barrier to enzymes and prevents penetration of lignocellulytic enzymes into the interior structure
fungi have special ligninases that can break it down but it takes ages
brown rot fungi - breaks down the cellulose by using hydrogen peroxide produced from hemicellulose - diffuses into the tissue leading to decay and cracks into cuboids
describe how pathogenic fungi decay trees
access the centre of the tree via the xylem of phloem
dead material in the centre is degraded and pathogen moves outwards
lichens are a mutualistic symbiotic relationoship between what?
fungus and an algae/cyanobacteria
describe the relationship between fungi and alage in lichen
alage provides food for the fungi and the fungi provides water and protects the alage from the environment
what are the two types of mycorrhizae
endo - hyphae penetrate the cells
ecto - hyphae dont penetrate the cells
3 types of endomycorrhiza
arbuscular - form structures within cells
ericoid
orchidaceous mycorrhiza
the two ways of infection by fungi
necrotrophic
biotrophic
how do necrotrophs work?
destroy host tissue via hydrolytic enzymes then feed on the dead plant material
how do biotrophs work
invade tissue without killing it and rely on the living tissue
what triggers a hemibiotroph to become a necrotroph
penetrating the tissue
what is the infecting structure of airborne biotrophs called
appressorium
what is the response of plants to destroy an invading biotroph
kill their own cells
what is the haustorium?
a specilaised hyphae used to extract nutrtients from living cells in biotrophs
why are biotrophs a large problem to argiculture
reduces yield as photosynthesis reduces
pathogen reduces defence and hence suseptibility to other diseases
what type of fungus causes the following diseases
stem rust - basidiomycete
powdery mildew - ascomycete
cost of necrotrophs to agriculture in USA through the 1990s
3 billion
describe mycotoxin deoxynivalenol aka vomitoxin
virulence factor
problem in devleoping countries
binds to ribosomes causing cell deaths
dutch elm disease was caused by _______ spread by _____
ascomycete fungus spread by elm bark bettle
describe biocontrol techniues to deal with fungal pathogens
hyperparasitic fungi grow on the bad fungi
what is intersting about the cordyceps phyla
type of ascomycetes that are involved in causing insects to become zombie like
describe the nematophagus fungus
eats nematodes
inflatable loops and snares
what is chytridomycosis? describe its unique reproduction strategy when a japanese tree frog is its host
disease caused by chytrid fungus that infects amphibians worldwide
invades skin and f=grows infected skin cant osmoregulate
makes japanese tree frogs make longer calls which attracts more females increasing the chance of the pathogen spreading
