Fungi (Lec. 11) Flashcards
Describe the general structure and function of the nucleus
Holds genetic material
Describe the general structure and function of mitochondria
Powerhouse of the cell
Describe the general structure and function of a chloroplast
Holds chlorophyll; does photosynthesis
Describe the general structure and function of a ribosome
Synthesizes proteins
Describe the general structure and function of the endoplasmic reticulum
Lots of layers; rough ER synthesizes proteins and smooth ER synthesizes lipids
Describe the general structure and function of the golgi apparatus
Vesicle that packages things
Describe the general structure and function of a lysosome
Digests waste
Describe the general structure and function of the cytoskeleton
structure that helps the cell maintain its shape and internal organization
Define fungi
Any group of spore-producing organisms feeding on organic matter; part of the Fungi kingdom
Define yeast
A microscopic unicellular fungus; usually facultative anaerobes; that reproduce by budding and are capable of fermentation
Define mold
Usually aerobic multicellular filamentous fungi
Define thallus
An organism with no apical growth (not differentiated into stem and leaves or whatever); lacks true roots and a vascular system
Define mycelium
The vegetative part of a fungus, consisting of a network of hyphae
Define conidia
A spore in asexual or sexual reproduction that detaches from the parent and germinates into a new mold
Define hypha
Long filament structures that absorb nutrients or are used for reproductive function
Define ascus
A sac in which ascospores develop
Define Ascospores
A sexually produced fungal spore from the phylum of Ascomycota that forms within an ascus
Define Basidiospores
A sexually produced fungal spore from the phylum Basidiomycota
Define Zygospores
A sexually produced fungal spore from the phylum Mucoromycota
Does the fungal phylum Microsporidia have sexual spores?
No
Define plasmogamy
The stage of fungal sexual reproduction in which one haploid nucleus (+) penetrates cytoplasm of another haploid recipient cell (-)
Define karyogamy
The stage of fungal sexual reproduction in which two haploid nuclei fuse to form a diploid zygote
Define mycosis
A fungal infection
What are the five different types of mycoses (and describe)
Systemic mycoses: deep within the body, affecting tissues/organs
Subcutaneous mycoses: beneath the skin
Cutaneous mycoses: affect hair, skin, and nails
Superficial mycoses: localized (e.g. hair shafts)
Opportunistic mycoses: fungi harmless in normal habitat but pathogenic in a compromised host
List the defining characteristics of fungi and differentiate them from bacteria
Fungi are heterotrophic eukaryotes that are vegetative and survive at more acidic conditions; can be facultative anaerobes or aerobic; are less susceptible to osmotic pressure and antibiotics.
What are the four medically important phyla?
Mucoromycota, Microsporidia, Ascomycota, Basidiomycota
Differentiate asexual from sexual reproduction and describe for each of the medically important phyla
Mucoromycota: asexual sporangiospores and sexual zygospores
Microsporidia: asexual sporangiospores and no sexual spores
Ascomycota: asexual conidiospores and sexual ascospores
Basidiomycota: asexual conidiospores and sexual basidiospores
Describe the life cycle of a Mucoromycete
Asexual: A hypha produces a sporangium, which bursts to release sporangiospores. A sporangiospore germinates and produces hyphae; a vegetative mycelium grows. Sexual: Gametes form at the top of a hypha and plasmogamy occurs. A zygospore forms and karyogamy and meiosis occurs. The zygote produces a sporangium, which then releases spores, and the whole thing starts all over.
Describe the life cycle of a Microsporidian
Only asexual reproduction: Sporangiospores are ingested or inhaled by an organism, and the spore injects a tube into the host cell. The spore’s cytoplasm and nucleus travels through the tube and into the host cell. The cytoplasm grows and the nuclei reproduce. The cytoplasm breaks up to form spores, which are then released by the cell.
Describe the life cycle of an ascomycete.
Asexual: a hypha produces a conidiophore, and conidia are released form it. A conidium germinates to produce a hyphae; vegetative mycelium grows.
Sexual: from the mycelium, plasmogamy occurs, then karyogamy (an ascus forms), then meiosis then mitosis. The ascus opens to release ascospores, and the ascospores can germinate to produce hyphae.
Describe the life cycle of a basidiomycete.
Asexual: A hyphal fragment breaks off vegetative mycelium, and the fragment grows to produce new mycelium.
Sexual: Plasmogamy occurs from the vegetative mycelium. A fruiting structure (“mushroom”) develops. Karyogamy occurs, and Basidia form diploid nuclei. Basidiospores are formed by meiosis, then they mature and are discharged. They can germinate and produce hyphae.
Differentiate between yeasts, molds, and dimorphic fungi
Yeasts: nonfilamentous and unicellular. Budding yeasts divide unevenly and fission yeasts divide evenly.
Molds: multicellular filamentous fungi that are usually aerobic.
Dimorphic fungi grow as molds below 37 degrees C and as yeast above.
Explain how hyphae and spores relate to fungal growth
Spores can germinate to make hyphae, which can grow to create mycelium.
List the methods commonly used to identify fungal isolates in the lab
Colonial morphology, microscopic and macroscopic morphology. Immunological tests are very rare but there is a CSF antigen test for C. neoformans.