Flashcards in Eukaryotic Microbes Deck (73):
What domain are fungi in?
Do fungi contain sterols in their membranes?
What are the multi-cellular and uni-cellular forms of fungi called?
Multi-cellular = molds and mushrooms. Uni-cellular = yeast
What nutrient type are yeast?
Chemoheterotrophs organic molecules are the carbon source and the energy source
What is the food acquisition method fungi use?
Absorptive (saprotrophic) - produce and secrete enzymes that degrade the substrate and the products are then absorbed
Fungi form symbiotic relationships. What does this mean?
It's a form of mutualism so both partners benefit
A symbiotic relationship fungi form with plants is called
The symbiotic association composed of a fungus and the roots of a vascular plant consists of both partners benefiting. How?
The plant obtains minerals such as phosphates and the fungi obtains sugars/amino acids
There are two types of mycorrhiza, what are they?
Endomycorrhiza and ectomycorrhiza
What happens in endomycorrhiza?
The fungi penetrates the cortical cells of the roots for the symbiotic relationship
What happens in ectomycorrhiza?
The fungi surrounds the roots for the symbiotic relationship
Fungi can form a symbiotic relationship with green algae/cyanobacteria. How do they both benefit?
The algae/cyanobacteria gets nutrients and the fungi gets sugars
Fungi can play a role in pest control against...
Nematodes, weeds, mites and other fungi
Fungi are food both directly and indirectly. Explain this statement.
Mushrooms - directly. Indirectly - cultured foods.
Which fungi is used to make bread and beer?
Which fungi is used to make quorn?
Fungi can be used for medicinal purposes, what is an example of an antibiotic from a fungi?
Fungi can be used for medicinal purposes, what is an example of a immunosuppressive from a fungi?
Fungi can be used for medicinal purposes, what is an example of a bacteriostat from a fungi? Remember a bacteriostat prevents bacteria from multiplying without destroying them.
Fungi can be used for medicinal purposes, what is an example of a vasoconstrictor from a fungi?
There are around 200 species of fungi that are pathogenic to animals and humans. Many are nosocomial (hospital acquired) Give some examples.
Aspergillosis, candidiasis, cryptococcosis, pneumocystis
What are mycotoxins?
They are compounds produced by some fungi that are toxic to humans/animals
Give two examples of a mycotoxin.
Amatoxins and aflatoxins
Where are amatoxins found?
Found in Amanita mushrooms - Amanita phalloides.
How are amatoxins fatal?
They are selective inhibitors of RNA polymerase II which is a vital enzyme in the synthesis or mRNA. Without mRNA which is the template of protein synthesis, cell metabolism stops. Causes kidney/liver damage too which is fatal.
What produces aflatoxins?
Aspergillus, A. flavus
How do aflatoxins cause liver failure (cirrhosis/carcinoma)?
The toxins can intercalate with DNA, damage DNA bases by alkylation (transfer of one alkyl group to another)
Why are fungi problematic when it comes to plants?
Thousands of species are plant pathogens - economic importance (rusts, smuts, mildews)
How can fungi be problematic when it comes to food?
They cause food spoilage
The fungal cell wall is...
The fungal cell wall is present to protect the underlying
The fungal cell wall determines and maintains the shape of the
The fungal cell wall acts as an interface between the fungus and the
The fungal cell wall is the binding site for some
The fungal cell wall allows interactions with other
The fungal cell wall is multi-
What three layers make up the fungal cell wall?
Chitin, glucans and glycoproteins
What component makes up the smallest percentage of the fungal cell wall?
What percentage of the fungal cell wall does chitin make up in yeast?
What percentage of the fungal cell wall does chitin make up in multicellular yeast such as Neurospora and Aspergillus?
What is chitin?
A polymer of N-acetylglucosamine
How does the N-acetylglucosamine molecules bind together to form a polymer in the fungal cell wall?
By forming chains - beta 1-4 linkages
How do the beta 1-4 linkages of N-acetylglucosamine forming the chains actually connect with others?
Through inter-chain hydrogen bondings which form microfibrils
What is the function of the chitin in a fungal cell wall?
To provide stability to the cell wall
What is glucans in a fungal cell wall?
A polymer of glucose
What percentage of a fungal cell wall is made up of glucans?
About 50-60%, it is a major component
What is glucans made of?
A polysaccharide of D-glucose
What linkage is between saccharide molecules making up the polysaccharide of glucans in the fungal cell wall?
Mostly beta 1-3 linked
What is the function of glucans in a fungal cell wall?
To function as an attachment site for other wall components
What percentage of the fungal cell wall is made of glycoproteins in yeast?
What percentage of the fungal cell wall is made of glycoproteins in filamentous fungi?
Where are the glycoproteins found in a fungal cell wall?
Tightly interwoven in the chitin/glucan matrix
Different fungi have different _____________ in their fungal cell wall
What type of glycoproteins are present in yeast?
What type of glycoproteins are present in N.crassa and A.fumigatus?
Glycoproteins allow adhesion to
Glycoproteins protect the fungus from
Glycoproteins allow the synthesis of other
cell wall components
How do fungal molds grow?
Grow as tube like, multi cellular filaments called hyphae
What are hyphae in soil called?
What is the role of hyphae?
To scavange nutrients
Vegetative hyphae grow together to form a compact mass. What is this mass called?
The portion of the hyphae that obtains nutrients is called the
The portion of the hyphae concerned with reproduction is
the ariel hyphae - often bares reproductive spores
Why is the ariel hyphae called what it is?
The ariel hyphae projects above the surface of the medium.
There are two types of vegetative hyphae, what are they called?
Septate hyphae and coenocytic hyphae
Describe the septate hyphae.
The hyphae contain cross walls which divide them int distinct, uni-nucleate cell like units
Describe the coenocytic hyphae.
Hyphae contain no septa, forming long continous cells with many nuclei
Where do the vegetative hyphae grow from?
At the tip
The growing tip is special because of three reasons. What are these reasons.
Structurally and functionally very different from the rest of the hypha
The cytoplasm appears more dense
No major organelles
Where do vegetative hyphae grow from and what is this known as?
At the tip - apical growth
What does the growing tip of a vegetative hyphae contain?
A structure where Golgi-derived vesicles accumulate known as the Spitzenkorper