Mycoses I Flashcards
What are fungi, and how do they differ from plants?
they are eukaryotic chemoheterotrophic microorganisms that do not contain chlorophyll
What are chemoheterotrophs and saprobes, and what role do fungi play in ecosystems?
chemoheterotrophs absorb organic matter from the environment and most fungi are saprobes that feed on dead or decaying matter
what are Mycoses?
diseases caused by pathogenic fungi that feed on living plants or animals
Many serious (systemic) fungal infections are caused by
opportunistic pathogens, which mainly affect people with weakened immune systems
what are the two forms of fungi used to make antibiotics?
Molds and yeasts
what is dimorphism in fungi
fungi can change their form depending on environmental conditions — specifically temperature
- molds at cooler temperatures
- yeasts at warmer temperatures
what are examples of dimorphic fungi?
Histoplasma capsulatum Cryptococcus neoformans and Candida albicans
what is the cell structure of fungi?
- cell walls contain chitin, glucans and mannans
- cell membrane contains sterols (ergosterols)
- one nuclei surrounded by a nuclear membrane
what is the structure of molds?
Molds are made of thread-like filaments called hyphae, which grow, branch out and secrete enzymes to break down complex materials into nutrients they can absorb — a process called extracellular digestion
what happens when hyphae clump together?
they form a mycelium, which acts like a feeding network and also contain reproductive structures
what are septate hyphae?
hyphae that have cross-walls called septa that divide the hypha into compartments but are incomplete, allowing nutrients, organelles, and even nuclei to flow freely through them
what are non-septate hyphae (Coenocytic)?
species that do not have septa, so the entire hypha is one continuous cell but still contain multiple nuclei, floating freely throughout the structure
what are the two main phases of the fungal life cycle?
- Asexual Phase: vegetative growth and reproduction without fusion of gametes (most common)
- Sexual Phase: Occurs less often and involves the fusion of nuclei from two different fungal cells
what is sporulation?
main way fungi reproduce and spread by forming spores which land in a suitable environment, germinate and form hyphae
what are the types of asexual spores (conidia)?
In Molds:
- Sporangiospores
- Conidiospores
- Arthrospores
- Chlamydospores
In Yeasts:
- Blastospore
what are sporangiospores?
spores made by fungal hypha inside a structure called a sporangium that releases the spores when it bursts open
what are conidiospores?
exposed, dust-like fungal spores that bud off from hyphae without being enclosed in a sac and spread easily in air
what are arthrospores?
spores formed by fragmentation of fungal hyphae by the hypha breaking apart into individual cells
what are chlamydospores?
Thick-walled, round or oval spores formed inside hyphae or at the tips of hyphae that are not meant for spreading, but for surviving
how do yeast reproduce (asexual)?
through a process called budding where a small part of the yeast cell swells and forms a bud that grows and becomes a new cell called a blastospore which eventually breaks off and lives on its own
what are pseudohyphae?
elongated chain of yeast cells that don’t completely separate from the parent cell during budding and that have less rigid walls
what are the main fungi that reproduce sexually?
Zygomycota
Ascomycota
Basidiomycota
Blastomycota
yeast that reproduces asexually through budding and form blastoconidia (blastospore)
how does sexual reproduction occur in Zygomycota?
fungal body called the mycelium contain a “+” mating type and a “–” mating type that fuse together to form a zygospore which then has its nuclei separate in a sporangium to form sporangiospores that are later released
