L16/17/18 Flashcards
describe fungi
- eukaryotic (filamentous (has mycelium + spores)- mold + fungi) or prokaryotic (yeasts)
- have a cell wall containing chitin
- chemoheterotrophs
-absorb food (simple carbs) - have sexual + asexual spores (mycelium can do both)
- non motile, except spores of chytridomycota
- grow in more acidic conditions then bacteria
- like moisture
- temp. can trigger different reproductive phases
asexual vs sexual reproduction
used to differentiate phyla
asexual (anamorphic)
- mitosis
- genetically identical
-favourable in stable conditions, no need to adapt
sexual (teleomorphic)
- offspring vary due to mix of 2 parents
- occurs under unfavourable conditions, need to adapt to survive better
yeasts vs dimorphic vs multicellular fungi
yeast
- non filamentous (unicellular)
- spherical/oval
- replicate via budding (divides unevenly) or fission (split into 2)
- larger then bacterial cocci
- obvious internal structures
- grow with sugars + high nutrients
- mostly facultative aerobes
- can be genetically altered to produce beta lactam antibiotics, riboflavin (vitamin), produce steroids
dimorphic fungi
- exists as both yeast (budding) and mold (spore forming) at different conditions
multicellular
- network of filaments
- mycelium- mass of hyphae, is able to provides support + absorbs nutrients
- visible to naked eye
- can have symbiotic relationships
explain hyphae
- tubes made of a rigid wall, contains protoplasm
- tufts of hyphae on surface that intertwine
- some have a septate- cross wall, regular intervals (1 or more nucleus in each section)
- hyphal branches produce reproductive spores (aerial- on the inside, hydrophobic vs vegetative- on the outside, hydrophilic)
asexual vs sexual lifecycle of fungi
asexual
- has spore producing structures that release spores (3 different types- conidium (not enclosed in a sac), arthrospores, chlamidospores, sporangiospores (formed in a sac, sporangium, at the end of aerial hyphae)
-germinate
-repeat
sexual
- undergo plasmogamy (fusion of cytoplasm of 2 fungal species)
- enter heterokaryotic stage (cell contains 2 genetically different nuclei)
- enter karyogamy (fusion of nuclei), produce zygote
- undergo meiosis
- has spore producing structures (ascus- enclosed sack, within has a basidium, club shaped structure, spores formed on) that release spores
-germinate
-repeat
major phyla
fungi- chytridomycota (have motile spores), zygomycota, glomeromycota, ascomycota, basidomycota
note actinomycetes is NOT a fungi, actually bacteria despite forming aerial hyphae)
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explain glomeromycota
- small group
- form endomycorrhizae
- related to herbs
- cannot grow without plant
-produces asexually, spores
-multinucleated
explain chytridomycota
- asexual AND sexual spores,
-asexual- has thin walled sporangium containing zoospores (motile + flagellated, need water) - sexual- thick walled sporangium- haploid zoospores to gametes
- free living or parasitic
-multi or uni celled
explain zygomycota
- has a role in food spoilage, soil, decay of plant
- some parasitic
- has asexual and sexual phases
- produces zygospores (sexual), which produce sporangium which release meiospores
- produce sporangium + sporangispores (asexual)
-multicelled
explain basidomycota
- largest group
- has basidium- single celled club shaped structures, basidiospores formed by meiosis
-has septate hyphae- in a clamp connection
-mainly sexual reproduction - mashroom shape
explain ascomycota
- e.g. yeast
-highly diverse - uni and multi celled
- has septat ehyphae
- primary decomposer of dead plant material
- can form a symbiotic relationship with plant roots (lichen commonly)
-some pathogenic - has sexual (produce asci cells) and asexual (conidia produces conidiophores) reproduction
how does yeast reproduce
- budding
- asexual reproduction, then make mating pairs, cell fusion occurs, nuclear fusion occurs, then meiosis, forms ascus (caused by starvation), produces ascospores, which germinate, then repeat
how do pathogenic fungi work for plants
specialised hyphae (haustoria), penetrate plant cell wall, use cell cytoplasm for nutrition
e.g. dutch elm tree disease
types of mycoses: superficial, cutaneous, subcutaneous, systemic, opportunistic
mycoses- infection as a result of fungi
Superficial- surface of something that’s dead
Cutaneous- on surface of living
Subcyntaneous- slightly deeper
Opportunistic- internal organ, but only if immunosuppressed or wounded
why is the production og mycotoxins a major health concern for fungal growth in food
- determinental changes to nutrition status
- change aesthetic, cause discolouration
-development of wierd flavours/smells - cause food to rot
- lead to allergenic
