Week 3 Flashcards
What domain of the tree of life are fungi under?
Eucaraya
Why are fungi frequently used for biological research?
They are very closely related to animals in the tree of life.
What type of organisms are fungi ?
Non-photosynthetic eukaryotic heterotrophs.
Define heterotroph.
An organism deriving it’s nutritional requirements from complex organic substances.
What type of organisms do fungi originate from?
Marine organisms with flagella
What are the main roles of fungi?
Saprotrophism
Act as pathogens, symbionts and endophytes
What is Saprotrophism ?
Decomposition of organic tissue
Define symbionts.
Organisms which have a mutually beneficial relationship with another organism.
What are endophytes?
A plant or fungus which lives inside another plant.
Outline the biological, general structure of fungi?
Eukaryotic
Multicellular
What are the 2 types of fungal hyphae?
Septate hyphae
Aseptate hyphae
What is a septate fungal hyphae?
Septa’s divide hyphae into cells with separate nuclei and organelles
What are aseptate hyphae?
No separate cells in the cytoplasm so some cells have many nuclei and organelles.
What is the entire hyphal mass of a fungi called?
Mycelium
What is a fungal hyphae?
Fungal hyphae contain the cytoplasm or cell Sao , including nuclei.
They also absorb nutrients from the environment and transport them to other parts of the cell
What is the correct term for the fungal body?
Thallus
What is meant by the term coenocytic ?
Continuous mass of cytoplasm enclosed by one cell wall
Outline the structure of aseptate fungi.
Not partitioned into smaller cells.
Multi-nuclear cells.
Coenocytic
What is the benefit of aseptic fungi having no partitions between cells?
Makes cellular communications extremely easy and means that no complex mechanisms are required.
Describe the structure of septate fungi.
They have septa which are cross walls that divide cells in the fungal mycelium.
Each cell has only 1 or 2 nuclei.
Nuclear division is followed by cross wall formation.
When are cross walls formed in septate fungi?
After nuclear division
How many nuclei are within each cell of septate fungi?
1or 2
Why do Candida albicans have high disease causing activity?
They are able to change forms very quickly.
They are initially a budding yeast but can switch to hyphal forms and other forms on lab agar plates.
What type of research are Candida albicans frequently used for ?
Analysing genome sequences.
What was the first eukaryote to be fully genome sequenced when did this occur ?
Candida albicans
1995
BY what methods do fungal grow?
Apical growth
What do fungal spores eventually grow into?
Mycelial mats
Which part of the fungae grow?
The edge
Hyphae
What is required for apical growth of fungi to be continuous?
When there is suitable food available.
Why is apical growth so critical to saprotrophic fungi?
Cellulose decaying enzymes cannot diffuse into woody tissues.
What do pathogenic fungi do apical growth for?
To generate hydrological pressure to penetrate host defences.
What feature is at the very end of a hyphal tip of fungae?
Spizenkorper
What is a Spizenkorper?
A pointed body with a cluster of small, membrane bound vesicles,ew embedded in a meshwork if actin filament.
Found at the very end of fungal hyphae.
What are apical vesicles?
Vesicles produced by golgi vesicles and transported by the top elements (hyphae)of the cytoskeleton such as microtubules and actin filaments.
Describe the cell walls in the apex of fungal hyphae.
Very weak
Define syncytium
A single cell or cytoplasmic mass containing several nuclei, formed by fusion of cells or division of nuclei.
How can apical growth of fungi be visualised?
By fluorescent microscopy using green light fluorescence.
Define taxonomy.
The science of classification. Provides an orderly basis for the naming of organisms and placing them in a category (taxon).
What is the original of the binomial nomenclature for fungus?
Linnaeus
How are fungus named?
First name = genus
Second name = specific epithet
Outline the order of the classifications if naming organisms
Kingdom Phylum or division Subphylum Class Order Family Genus Specific epithet Subspecies
What are the eight phyla of the fungal kingdom?
Ascomycota Basidomycota Mucoromycota Zoopagomycota Neocallimastigoycota Chytridiomycota Blastocladiomycota Cryptomycota
What are the 2 largest fungal species?
Ascomycota
Basidiomycetes
What are constituents of ascomycota?
Filamentous fungi and yeasts
How are ascomycota characterised?
The production of spores in an ascus during sexual cycle
What is an ascus?
A cylindrical sac in which the spores of fungi develope
What type of reproduction do basidiomycetes reproduce?
Sexual and rarely asexual
What structures can be formed by basidiomycetes during growth/ propagation?
Basidocarp
Basidiospore
Describe the mycelium of chytridiomycota ?
Aseptate
How do hyphae of chytridiomycota often change in food ?
They often branch to form rhizoids
Describe the chromosomal content of chytridiomycota cells
Predominantly haploid
Some short diploid and dikaryotic phases in the sexual cycle
Define dikaryotic
2 nuclei in each cell
What is the cell wall of chytridiomycota composed of ?
Chitin
Where do chytridiomycota habit?
Moistened terrestrial habitats such as forests, litter layers, freshwater, marine areas, dead tissues
Who invented gram staining techniques?
Hans Christian Gram
Outline the procedure for carrying out a gram stain.
- Spread culture into a thin film over a hear greater slide.
- Dry in the air
- Flood the slide with crystal violet for 1 minute
- Add iodine solution
- Depolarise with alcohol for 30 secs (often ethanol)
- Counter stain with Safranin
What is the purpose of depolarising the cells with ethanol during a gram staining process?
Dissolved cell walls to enable staining.
What must be used to identify bacteria that have been gram stained when using microscopy?
Immersion oil
100x magnification
What colour do gram positive bacteria appear at the end of a gram staining procedure?
Purple
What colour do gram negative bacteria appear at the end of a gram staining procedure?
Pink
Outline how the colour of gram positive bacteria changes with each dye added in a gram straining procedure.
Crystal violet. Purple/ blue
Iodine. Purple
Ethanol. Purple
Safranin. Purple
Outline how the colour of gram negative bacteria changes with each dye added in a gram straining procedure.
Crystal violet. Blue
Iodine. Purple
Ethanol. Clear
Safranin. Pink
Why do we identify bacteria?
To diagnose and treat infections.
To identify contaminating agents.
For epidemiology.
What features are used to identify bacterial species.
Morphology (shape) Chemical composition (identified by staining) Nutritional requirements Biochemical activities Source of energy
How are viruses identified?
They have a lot of proteins.
Highly immunogenicity.
Detection of specific antibodies and antigens.
Accurate and specific.
How are fungi and Protozoa identified?
Using microscopy.
Describe the chromosome content of most fungi.
Mostly haploid
Rare and short-lived diploid state.
What are the 3 methods by which fungi reproduce ?
Sexual
Asexual
Parasexual
Describe the asexual reproduction of fungi
Nuclei of somatic cells divide by construction or mitosis to form daughter cells which are them separated.
Describe the sexual reproduction of fungi.
Haploid nuclei from two different organisms fuse.
Mitosis then occurs to form haploid hyphae cells.
Haploid spores are separated.
What is the benefit of sexual reproduction over asexual reproduction?
Allows genetic variation to occur rather than just forming clones.
Outline the process of parasexual reproduction of bacterial cells.
The mycelium becomes heterokaryotic by anastomosis during the dikaryotic phase.
Some haploid cells within the mycelium can fuse to form a diploid nucleus which then divide mitotically, along with the remaining haploid nuclei in the same mycelium.
What is the result of incomplete mitosis of fungi?
Haplodisation
What is haplodisation?
The production of a cell with a single set of chromosomes.
Define anastomosis.
The fusion of different fungal hyphae.
What are the main types of fungi that are pathogenic to humans?
Aspergillus fumigatus and Candida albicans.
What are the main type of fungi which are pathogenic to frogs or amphibians?
Batrachochytrium dendrobatidis
Name the types of fungi which are most pathogenic to insects.
Ophiocordyceps and unilateralis
Name the main types of fungi which are pathogenic to plants
Puccinia grammis, ustilago maydis
What areas of the normal human flora are Candida albicans present in?
Mouth, esophagus, vagina.
Name a type of opportunistic pathogen.
Aspergillus species
What is meant by a pathogen being opportunistic ?
An infections caused by pathogens that take advantage of an opportunity not normally available such as a weakened immune system.
What are the symptoms caused by bronchiopulmonary aspergillosis?
Mucus within the bronchi cause severe allergic reactions
What is caused by aspergilloma?
Mycelia ball in the lung cavity forms.
How do ophiocordyceps unilateralis infect insects?
Mycelia rupture through the head and other body parts of insects and form a stick-lick fruiting body liner with spores. Mature spores can fall onto colonies below.
How do chytrimycota affect the amphibians they infect?
They feed on the keratin in their skin and eventually lead to mortality.
In what you of fungi does symbiosis mainly occur?
Ascomycota
What is symbiosis in terms of fungi?
A partnership between specific fungi and photosynthetic Cyanobacteria
In symbiosis of fungi and a photosynthetic partner, what does each organism provide?
Photosynthetic partner provides organic food, organic molecules and oxygen.
Fungal partner provides carbon dioxide, water and minerals.
What are ectomycorrhyzae and what are their benefits to fungae?
Allow a symbiotic relationship between a fungal symbionts and the roots of a plant species by growing into the epidermis of a root and penetrating some of the plant root tissue.
What are the industrial uses of Saccharnocyes Cerevisiae?
Bakers yeast; used for making bread, beer and wine.
What is a lichen a symbiosis of?
Fungae and algae
