block C - fungi Flashcards
what are some characteristics of fungi?
theyre mostly multicellular
theyre eukaryotic
spores or resting bodies can sometimes be produced
what are hyphae?
they’re the ends of branching filaments and hyphae that extend above the surface can produce asexual spores called candida
hyphae form compact tufts called mycelia
what are most fungal cell walls made of?
chitin, the second most abundant biopolymer on the planet
what does mycorrhizae help with?
it helps plant roots obtain phosphorous
what are candida resistant to?
they’re often resistant to drying and are often pigmented
why do fungal cells produce spores?
they produce them in response to cell density or to search for nutrients
theyre really dispersal agents and allow the organim to disperse and spread
why do fungal cells often have hydrophobic outsides and grow from the tip?
it allows them to forage and branch in order to achieve exponential growth and form a network of hyphae
what are fruiting bodies?
theyre macroscopic reproductive structures and examples include mushrooms and puffballs
what is an example of a disease caused by fungi?
mycoses in humans causes athletes foot in the least serious cases and histoplasmosis in the most serious cases
what type of infection will 40% of people on life support die from?
candida infections
why do fruit bodies exist?
theyre a dispersal mechanism to release spores into the enviroment
what way do most fungi reproduce?
asexually
what are the three ways fungi can asexually reproduce?
- growth + spread of hyphal filaments
- asexual production of spores
- simple cell division (budding yeasts)
what ways can fungi reproduce sexually?
- sexual spores can originate from the fusion of 2 haploid cells to form a diploid cell
- spores (are resistant to drying, heating, freezing and chemicals)
what happens in a budding yeast cell when it reproduces?
the mother cell replicates its genome then the daughter cell closes off and grows until its almost the same size as the mother cell, where it buds off
how can you estimate the age of a yeast cell?
by how many bud scars it has
why are yeast a good model organism for ageing and gene research?
theyre very easy to introduce DNA into and theyre eukaryotic
fungi and animals diverged the latest from other eukaryotic cells, how long ago did they diverge form one another?
1.5 billion years ago
what are the key genera of chytridiomycetes?
allomyces and batrachochtrium
where are chytridiomyces commonly found?
in moist soil and freshwater
what problems with wildlife have chytridiomycetes caused?
theyve been implicated in massive die-offs of amphibians
what can all zygomycetes form?
zygospores
what do microspirida often infect?
they often infect immune-compromised individuals e.g. immune comromised individuals
what do all known species of glomeromycetes form with the roots of herbaceous plants?
endomycorrhizae
in some cases theyre also formed with woody plants and theyre essential for plant growth
why are glomeromycetes thought to have played an important role in the ability of early vascular plants to colonise the land?
they can solubilise phosphate and other nutrients and are able to utilise the carbon that plants have
what are the key genera of ascomycetes?
saccharomyces
candida
aspergillus
how can yeast cells switch from one mating type to another?
by a genetic switch mechanism
what are silent versions of yeast cells?
it means they have no promoter
what does the mating type switch facilitate in yeast cells?
it facilitates genetic interaction and swapping genes between organisms
what are the key genera of basidiomyces and what are they often described as?
agaricus, amanita
they’re often described as mushrooms or toadstools
there are over 30,000 described species
what type(s) of reproduction do basidiomycetes undergo?
vegetative and sexual
what is hyphal growth?
its basically the only way to grow exponentially through branching by more branches branching fom the newly formed branches
what is the spitsenkorper?
its the end of the branch
why are fungi important?
they’re one of the most important groups of organisms for nutrient cycling on a global scale
significant human and animal pathogens are fungal
biotechnologically and industrially important
what are the uses of fungi in medicine?
- antifungal drugs
- antibacterial drugs
what are microbial natural products?
theyre chemicals produced by microorganisms in nature as they give the microorganisms an adaptive advantage for resources and/or space
what is the problem with antifungal agents?
they target cellular processes that universally affect both humans and fungi because both of them are eukaryotic so this can lead to toxicity issues
what are primary metabolites?
theye stuff essential for life e.g. amino acids
what are secondary metabolites?
theyre stuff that help the cells in competition like antimicrobials
can fungi be pathogenic and cause disease?
yes
what does mycosis mean?
it means any infection caused by a fungus/ growth of a fungus on/in the body
who is most likely to get fungal infections?
immunocompromised people, normal healthy people arent likely to develop fungal infections
what are the range of seriousness that fungal infections can become?
they range from superficial, mild or self limiting infections like athletes foot all the way to systemic infections that reach the deepest of internal tissues and can become life threatening
how many species of fungi can cause disease in humans?
about 50
how can you detect that you have a fungal infection?
by studying the morphology of spores under the microscope for identification/ diagnosis along with molecular and immunological tools
what are the three main ways fungi can cause disease?
- inappropriate immune response (exposure to fungi causing allergic responses
- toxins (this is called myotoxins)
- host infection (this is called mycoses)
name a toxin produced by fungi and what does it do?
aspergillus produces toxins, the alphatoxin group is the most common, its highly toxic and carcenogenic, especially to birds
it also causes human diseases including cirrhosis (liver damage)
what does superficial mycosis affect?
it means the fungus only affects the surface layer of skin, hair and nails
why is superficial mycosis mostly treatable?
its mostly treatable with topical antifungal creams or liquid aerosols because fungi are eukaryotes and so are we so if you’re targeting other eukaryotes, youre also targeting your own cells
what are fungi that cause superficial mycoses collectively called?
dermatophytes
what does richophyton spp. cause?
fungal; infections of the feet and other moist surfaces
transmission is by spores that can be released by flaking and itching of skin
what is subcutaneous mycosis?
its a fungal infection that affects the deeper layers of skin
what are subcutaneous mycosis commonly caused by?
they’re caused by different fungi than superficial infections and sometimes the fungi can get under the skin through a cut
what can subcutaneous mycosis be treated by?
topical drugs
theyre often treated with oral administration of azole antifungal agents
what is Sporotrichosis caused by?
caused by the saprophyte Sporothrix schenckii
how can you get infected with sporotichosis?
occupational hazard of those working in close content with soil agriculture workers, miners, gardeners (spores can enter through cut skin)
what is chromoblastomycosis caused by?
caused by several species (Fonsecaea pedrosoi, Phialophora verrucose, Cladosporium carrionii, Fonsecaea compacta)