Lecture 15 and 16 Flashcards
What do fungi membranes contain?
Sterol
How many species of fungi are recorded?
More then 100,00 (estimated 1.5 million)
What nutrient type are fungi?
Chemoheterotrophs
How do fungi acquire food?
Absorptive (saprotrophic)
What type of digestion do fungi have?
Extracellular digestion: produce and secrete enzymes that digest substrate
How do fungi absorb digestion products?
Endocytosis, transporters
Name a symbiotic relationship of fungi with plants.
Mycorrhizae (plants get minerals/phosphate, fungi get sugars/amino acids)
What are the two type of mycorrhizae?
Endomycorrhizae (penetrates coritcal cells of root), ectomycorrhiza (surrounds root)
What are lichens?
Green algae/cyanobacteria and fungi
What can fungi act as pest control against?
Nematodes, weeds, mites, other fungi
What is the break down and consumption of environmental pollutants called?
Bioremeidation
Name an immunosupressive fungi
Cyclosporins
How many pathogenic fungal species are there to animals and humans?
Around 200, most nosocomial and/or opportunistic
Name an oppertunistic infection of fungi in AIDs patients.
Crytococcal meningitis
Aspergillosis fungi can cause…
Pulmonary aspergillosis or invasive aspergillosis
What toxic compounds do some fungi produce?
Mycotoxins, such as amatoxins
What does Amanita phalloides (Death cap) produce?
Alpha-amanitin which inhibits RNA polymerase II
Alfatoxin. flavus metabolites intercalates with DNA, which…
Damages DNA bases (alkylation) promotes oncogene mutations
How does fungal cell wall protect underlying cytoplasm?
Provides stable osmotic environment
What is chitin made of?
N-acetylglucosamine polymer, chains with beta 1-4 linkage
Chitin function?
Cell wall stability
What is a pollysaccharide of D-glucose found in cell wall?
glucans (50-60%)
Linkages in most glucans?
beta 1-3 linked
Glucan function?
Attachment site for other wall components
Where are glycoproteins found in the cell wall?
Outer surface, interwoven over chitan/glucan layer
Function of glycoproteins?
Adhesion to surfaces, fusion of fungi, protection, molecule uptake, signal transduction, synthesis
Plasma membrane sterol is?
Ergosterol
What does ergosterol do?
Reduce membrane fluidity and permability
Antifungal drugs target what biosynthesis pathway?
Ergosterol
2 types of vegetative hyphae:
Septate hyphae
Coenocytic (aseptate) hyphae
What is growth at the tip of vegetative hyphae called?
Apical growth
Features of growing tip:
- Structure/function different
- Denser cytoplasm
- No major organelles
WHat does growing tip contain?
Spitzenkorper
What is spitzenkorper?
Structure where golgi-derived vesicles accumulate, which exocytosis
What do the spitzenkorper vesicles contain?
Enzymes involved in wall lysis, wall synnthesis, precursor wall polymers (mannoproteins)
Name when growing tips fork
Bifurcate
Vegetative hyphae can extend out of the substrate to form what?
Aerial hyphae
How do aerial hyphae produce asexual spores?
They undergo mitosis and subsequent cell division
What are the 2 types of asexual spore?
Conidiospores
Sporangiospores
What are conidiospores?
Spores produced in non-enclosed chains at the end of aerial hyphae
What are sporangiospores?
Spores produced in specialised cells at the end of aerial hyphae, remain enclosed in sporangium (sac) until mature
Asexual spores germinate to produce
hyphae
What are compatible mating fungi
- and + strains, which attract each other using chemicals
First stage of sexual reproduction in multicellular fungi
Plasmogamy
What is plasmogamy
Hyphae fuses, cytoplasm mixes, + haploid nucleus enters recipient cytoplasm
What are some plasmogamy exceptions?
Some fungi nuclei remain apart, develop dikaryotic mycelium, gives rise to fruiting body (mushroom, toadstool, cap)
What is the second step of multicellular fungi sexual reproduction?
Karyogamy
Where does karyogamy occur in fruiting bodies?
Gills
What is karyogamy?
- and + nuclei fuse to form diploid zygote nucleus
What is the third phase of sexual reproduction in multicellular fungi?
Meiosis
How many unicellular fungi (yeast) species have been described?
around 1500
How do most yeasts divide?
Budding
Give an example of a budding yeast
Saccharomyces cerevisiae
Stages of budding
Protuberance (bud) forms on surface of parent cell
Bud elongates
Nuclei/organelles divide
Cell wall material laid down between parent and bud
How many times can a yeast bud?
Up to 24 times
What forms when incomplete buds remain attached to parent?
Psyedohyphae
Name a yeast that divides by binary fission
Schizosaccharomyces pombe
Stages of binary fission in yeast.
Parental cell elongates
Nuclei/orgalles divide
Segregation of nuclei and organelles
Cytokinesis
Name a dimorphic fungi that is goverened by CO2
Mucor indicus (In algae, mold like, on agar, yeast like)
Name a dimorphic fungi governed by temperature
Histoplasma capsulatum (yeast at 37, mold when lower)
What does Histoplasma capsulatum cause?
Histoplasmosis (TB like infection in lower respiratory tract)
Fungal infections are called
Mycosis
5 groups of fungal disease
Systemic mycoses Subcutaneous mycoses Superficial mycoses Cutaneous mycoses Opportunistic mycoses
Systemic mycoses caused by and transmission by
Soil fungi
Spore inhalation
Name a systemic mycoses
Histoplasmosis caused by Histoplasma capsulatum
What causes and what is the route of transmission of subcutaneous mycoses?
Saprophytic soil fungi
Spores/hyphae in wound
Name a disease and fungi associated with subcutaneous mycoses
Sporotichosis caused by Sporothrix schenkii
What do cutaneous mycoses secrete?
Keratinase (degrades keratin)
Example of cutaneous mycoses
Ringworm (trichophyton species)
Atheletes foot
What drugs inhibit Beta (1-3) glucan synthase?
Echinocandins (fungicidal against yeast, fungistatic against molds)
What drugs bind ergosterol?
Polyenes
What drugs inhibit ergosterol biosynthesis?
Imidazole
Name another class of drug that is exploits fungal plasma membranes.
Triazole
How many species of protozoa?
20,000
How do protozoa digest food?
In food vacuole
How do protozoa eliminate waste?
Plasma membrane or anal pore
Amoeba contain:
Endoplasm (central)
Ectoplasm (clear)
Protozoa cilia and flagella are also called…
Undulipodia
Undulipodia consist of:
Basal body, axoneme (9+2 arrangement), plasma membrane
Trypanosome, leishmania have how many flagellum?
1
What protozoa have multiple flagella?
Giardia, trichomonas
Name protozoa that uses cilia for feeding and swimming
Paramecium
Archaezoa features:
Lack mitochondria Some contain hydrogenosome/mitosome Symbionts in digestive tract Anaerobic 2 or more flagella form cysts
What is the causative agent of giardiasis?
Giardia lamblia
How does giardiasis spread?
Fecal/oral, anthroponotic and zoonotic
What is the causative agent of Trichomoniasis?
Trichomonas vaginalis
How does Trichomoniasis spread?
Sexually (hot tubs, wet bathing suits/towels/washcloths)
How does T.vaginalis attach to surfaces?
Axostyle
T.vaginalis features
No cyst stage
Can survive 24hrs outside host
What amoebozoa causes amoebic dysentry/amoebic liver abscesses?
Entamoeba histolytica
Plasmodium that causes malaria is what type of protozoa?
Apicomplexa
Number of deaths each year from malaria
0.6 million
Most common species that causes malaria.
P.vivax
Most deadly malaria species
P.falciparum
Name two more apicomplexa diseases
Cryptosporidiosis
Toxoplasmosis (spread through cat shit)
Name the group of protozoa with unusual organelles.
Euglenozoa
Name a disease and its bacteria caused by euglenozoa
Trypanosoma brucei causes African Trypanosomiasis
What transmits african trypanosomiasis?
tsetse fly
