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65 Cards in this Set
- Front
- Back
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describe nuclei of fungal cells
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eukaryotic with well-defined membrane
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what are in the cytoplasm of fungal cells?
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mitochondria and ER
bilayered cell membrane as innermost layer containing ergosterol, (essential sterol in fungi) |
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what is the fungus cell wall composed of? Describe:
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soft cell wall composed of chitin, glucans, proteins, polysaccharides, recognized as antigens
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What two forms do fungi grow as?
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yiests and mold
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monomorphic means?
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one form- grow either as yeasts or mold
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dimorphic means?
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can grow as yeasts and mold depending on environmental conditions e.g. temperature
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how can you identify fungi
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by asexual spore morphology, mode of formation, structure of spore bearing mycelium, arrangement of spores
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hyphae
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molds have these and grow by longitudinal extension and produce spores
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septate hyphae
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molds that have these are divided into individual cells by cross walls called septa
septa have pores through which organelles can move from one cell to another |
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mycelia
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molds form these- composed of clumps of intertwined branching hyphae
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coenocytic hyphae
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molds might have these
non-septate with nuclei in continuous mass of cytoplasm |
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Asexual spores of mold
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arthrospores
chlamydospores conidiospores sporangia |
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arthrospores
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(asexual)
hyphal segments formed by fragmentation of hyphae |
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chlamydospores
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(asexual)
thick-walled spores formed terminally or within hyphal segments |
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conidiospores
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(asexual)
formed at tips of hyphae, known as microconidia if small/unicellular and macroconidia if large and with more than one cell |
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sporangia
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(asexual)
-spherical, sac-like structures containing sporangiospores |
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favic chandelier structures
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-vegetative mold structure
multiple branched hyphal ends that resemble reindeer antlers or chandelier |
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knotted hyphae
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vegetative mold structure
closely twisted, entwined hyphae forming nodular structures |
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pectinate bodies
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hyphal projections that look like broken combs
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racquet mycelia
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vegetative mold structure
hyphae that consist of a chain of segments, each piece with an enlarged end, giving an appearance of a chain of tenneis racquets |
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taxonomic phlya for fungi
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-four main, classified by mode of sexual or asexual spore formation
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1. anamorphs
2. telomorphs 3. holomorphs |
1. asexual spores that can be simple, single celled bodies or multicellular
2. sexual reproductive structures 3. whole fungus |
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Phylum Ascomycota
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-sac fungi
-sex occurs in ascus (sac with 4-8 ascospores) |
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Phylum basidiomycota
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-club fungi
-sex produces basidiospores formed in the club shaped structure basidium |
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Phylum Zygomycota
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-conjugation fungi
-sex takes place by simple copulation of tips of multinucleate hyphae(no cross-walls) forming large thick walled zygospores resistant to environmental conditions |
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homothalic vs. heterothalic sexual reproduction
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sexual reproduction characteristic of Phlum zygomycota when cells of a single colony engage in sex vs. heterothallic when cells of different colonies engage in sex
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phylum deuteromycota
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asexually reproducing fungi producing conidia
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fungi replication: saprophytes
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how fungi grow, live on dead or living organisms
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can fungi produce their own energy?
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no they are heterotrophs that are saprophytes using dead and dying material as food
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how do fungi digest food?
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excrete extracellular enzymes that digest food outside of fungal cells
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what are the habitats of fungi?
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air water soil plants animals
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how do fungi disseminate?
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asexual spores primarily
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how do fungi reproduce asexually?
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budding (unequal division of two cells)
fragmentation (pieces of hyphae grow) spore formation (haploid cells) |
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when does asexual sporulation of yeasts occur?
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when budding produces blastospores
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pseudohyphae are?
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long chains of elongated yeasts
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why are fungi considered chemoheterotrophic?
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they obtain carbon compounds from nonliving organic material as saprophytes or from living tissue as symbionts
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1. necrotrophic vs. 2. biotrophic fungi
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1. faculative pathogens that live on damaged tissue and usually bring death of hosts
2. obligate pathogens, dependent on living host tissue Pathogenic symbionts can be either. |
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toxins secreted by fungi act as
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they are allergins causing granuloma formation
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mannan
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-virulence factor for fungi
-glycoprotein component of fungal cell walls, -suppresses lymphoblast formation and inhibits lymphocyte proliferation -inhibits keratinocyte proliferation by slowing epidermal turnover and allowing for a more persistent infection |
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virulence of fungi is determined by
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growth rate
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are virulence genes expressed the same ways all the time?
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these are expressed differently during different infections
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a fungi is considered avirulent if
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lacks invasive enzymes
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freezing fungi at 0 degrees centigrade
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(disinfection)
inhibits metabolism but does not kill vegetative forms or spores |
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desiccation
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(disinfection)
dryness inhibits fungal metabolism and kills most vegetative forms but not spores |
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what kills most fungal forms by denaturing proteins
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(disinfection)
heavy metals, chlorine, alcohol, phenol, formaldehyde, ethylene oxide and peroxide |
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what kills most fungal forms by damaging cell membranes?
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(disinfection)
soaps and detergents |
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what allows long term storage of fungi cultures and how?
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(disinfection)
lyophilization and freeze-drying inhibits fungal metabolism |
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ionizing radiation is
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-method of sterilization
-destroys DNA and kills most fungal forms |
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name methods of sterilization
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ionizing radation
autoclaving incineration |
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autoclaving
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-method of sterilization
121 centigrade -denatures proteins and kills all fungal forms |
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incineration
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-method of sterilization
exposure to 1000C- destroys all fungal forms |
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name diagnostic tests
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KOH
Periodic Acid Schiff rxn Giemsa Stain Nigrosin Stain |
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KOH
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quick and inexpensive way of viewing clinical specimens for fungal elements
causes tissue elements to dissolve, leaving fungal elements such as conidia or hyphae to be seen w light microscope |
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periodic acid schiff rxn
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used to stain polysaccharides in cell walls of molds and yeasts
has aldehyde groups that bind to fuchsin and stain fungal elements red |
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giemsa stain
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used when intracellular structures are examined
stains tissue and blood cells showing blue colored intracellular yeasts sometimes with halo |
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nigrosin stain
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used to demonstrate capsules around cells
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flucytosine
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interferes with pyrimidine metabolism and inhibits rna and dna synthesis
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griseofulvin
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inhibits fungal cell mitosis at metaphase by interaction with microtubules
disrupts mitotic spindles |
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pentamide isethionate
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interferes with nuclear metabolism by inhibition of DNA, RNA, phosplipid and protein synthesis
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amphotericin B and nystatin
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chemotherapeutic agent that binds to ergosterol in cytoplasmic membranes increasing membrane permeability
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fluconazole, itraconazole, ketoconazole, miconazole and thiabendazole
(ALL THE ZOLES) |
inhibit ergosterol synthesis by preventing conversion of lanosterol to ergosterol in cytoplasmic membrane resulting in loss of cell membrane integrity
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terbinafine
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chemotherapeutic agent that causes toxicity due to accumulation of squalene that depletes ergosterol in cell membrane
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chemotherapy compounds which affect membrane permeability
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amphotericin B and nystatin
Zoles terbinafine |
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chemotherapy compounds which affect DNA synthesis
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flucotosine
griseofulvin pentamidine isethionate |
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Periodic Acid-Schiff (PAS) reaction
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used to stain polysaccharides found in cell walls of molds and yeasts
has aldehyde groups that bind to basic fuchsin and stain the fungal elements red |
