fungal cell biology Flashcards
What can aggregations of amoebae differentiate into
Differentiate into spore-bearing fruiting structures
What is a plasmodium
Single cell containing many nuclei
What is the life cycle of plasmodial slime moulds
Fusion of swarm cells form plasmodium which becomes feeding network for plasmodium growth and movement
What is the cell cycle of yeast
1)bud emergence
2) spindle pole body separation
3)nuclear migration
4)nuclear division
5)cytokinesis
6)cell separation
What is a mycelium
A fungal network composed of multiple interconnected hyphae
Which cells exhibit tip growth
Fungal hyphae
Pollen tubes
Root hairs
Algal and fern rhizoids
Moss cell filaments
What are germ tubes
Specialised hyphae which emerge during spore germination and are involved in colony establishment
What do hyphae aggregate to form
Rhizomorphic mycelium
What is rhizomorphic mycelium
Thick strands of hyphae which have adhered to help fungus cover area, grow quickly and establish feeding network
What membrane fluorescent dye is used to visualise spitzenkorper
FM4-64
What is a spitzenkorper
Structure found in growing tips of fungal hyphae and key in its growth and development
What do the pores on septa allow for
Allow passage of organelles and cytoplasm between adjacent hyphal compartments
How can septal pores be blocked
Can be rapidly blocked if hyphae become damaged (e.g eaten by mites)
What are Golgi cisternae involved in
Golgi involved in glycosylation. and packaging in vesicles of secreted and integral membrane proteins
Where does hyphal fusion and additional growth occur
Occurs in colony interior as the colony matures
What is the term given to fungi which infect humans
Mycoses
What can dermatophytes cause
Ringworm, athletes foot, nail infection (example of parasitism)
How do commensal mycoses grow
Grow harmlessly on mucous membranes but can become invasive pathogens
How do opportunistic pathogens of the lungs grow
Found as saprotrophs but can grow in the lungs and invade tissues of immune-compromised individuals
How can an individual get sporothrix basiliensis (yeast-like fungus)
Opportunistic pathogen of wounds or traumatised tissue
What are characteristics of dermatophytes
Ascomycete fungi (sac-like structures)
Primarily asexual
Reproduce by asexual spores called conidia
What are features of dermatophytes
Living tissues not invaded as canot gorw at 37oC
Irritation leads to scratching => further dmg to tissues enabling bacteria to invade
Where can hyphal fronds grow
In planes of weakness within stratified substrate e.g skin flakes
What ability do dermatophytes have that contributes to disease growth
Ability to grow keratin rich substrates
What is candida albicans and where does it grow
Type of yeast that grows harmlessly as a commensal on mucous membranes of mouth, gut and vulvo-vagina tract
What is the route of infection by cryptococcus neoformans
Spores inhaled into lungs, lodging into alveoli, dissemination to CNS
What are pathogenicity factors of cryptococcus neoformans
Ability to grow at human body temp
Ability to grow in presence of 5% CO2
Capsule
Melanin
What are the 4 classes of antifungal compounds used to treat humans
Azoles
Polyene antibiotics
Echinocandins
Flucytosine
How do azoles function and what do they treat
Inhibit ergosterol synthesis - often used to treat candida albicans and superficial infections e.g athletes foot
What is ergosterol
Important component of the fungal plasma membrane
How do polyene antibiotics function
Associates with ergosterol in plasma membrane to form pores disrupting ion homeostasis in fungal cells
how do echinocandins function
Inhibit synthesis of B(beta)(1,3)-glucan, a major component of fungal cell walls
How does flucytosine function
Inhibits DNA and protein synthesis in fungal cells
How is the coprine mushroom toxic
The toxin inhibits aldehyde dehydrogenase => accumulation of acetaldehyde in the bloodstream
How is the orellanin toxin poisonous
The orellanin toxin affects the proximal tubules of kidneys and result in kidney failure
