Micro Flashcards
What is mycology?
The scientific study of fungi
What are some characteristics of fungi?
Eukaryotic Non-motile, rigid cell wall (chitin) Can be unicellular(yeasts) or multicellular (moulds) Saprophytes (feed of decomposing matter) or parasites Aerobes, some faculties anaerobes. Complex repro Classes based on sexual spores Insensitive to antibacterial antibiotics
Describe chitin and where it is found.
Chitin is a protective layer of chains of N-acetylglucosamine which is highly resistant to enzymatic breakdown. It is found within the fungal cell wall.
Discuss yeasts.
Type of fungi. Unicellular, spherical cells, 3-5um.
Reproduce asexually by budding, moist/mucoid colonies, facultive anaerobes.
Discuss moulds.
Filamentous fungi eg. Penicillin, microsporum.
Multicellular filaments, 2-10um wide (Hypae), can be septate(divided by cross walls), nonseptate (coencytic) or vegetative or aerial.
Reproduce sexually(spores) or asexually(condida)
Aerobic
Intertwined mass hyphae (mycelium/thallus)
What do septate hyphae possess that nonseptate don’t?
Septa-cross walls
Penicillin is septate, rhizopus is nonseptate
What are the two types of functional fungal hyphae? Briefly describe the cycle between the two.
Vegetative hyphae, reproductive hyphae
VH present on surface, fruiting bodies begin to grow and produce spores (RH), spores germinate into germ tube, hypha and then become vegetative hyphae again.
What temperatures are required for dimorphic fungi to grow in vitro and in Vivo?
In vitro - 25degrees Celsius
In Vivo - 37degrees Celsius
True or false. Many fungal species have a full lifecycle with both asexual and sexual states that are separated in time.
True
What is the sexual stage of a fungi lifecycle called?
Telomorphic.
Meiosis occurs producing meiospores.
What is the asexual period of a fungi lifecycle called?
Anamorphic.
Mitosis produces mitospores.
What are some types of asexual Filamentous fungal spores (mould)?
Sporangiospores.
Conidia.
What are the four main fungal classes?
Zygomycetes, ascomycetes, basidiomycetes, deuteromycetes.
What is pathogenicity?
Capacity to produce disease.
To cause disease a fungus must….
Enter host, multiply in host tissue, resist or not stimulate host defence, damage host.
What are the four forms of fungal disease in animals?
Infectious-parasitic fungi, mycoses.
Toxigenic-saprophyte or plant, mycotoxicoses.
Allergenic-sensitisation, mainly spores.
Effects on non-toxic spoilage-feed refusal, nutritional deficiencies.
What are the stages of fungal disease diagnosis?
The first 4 are the main forms.
- Clinical behaviour and appearance of lesions.
- Cytology of exudate/tissues-gram stain, KOH, etc.
- Fungal culture and appearance-macro and microscopic.
- Histopathology-gram stain, H&E, Etc.
- Immunofluorescence tests
- Molecular methods
- Skin tests
- Serology
- Animal inoculation
What are the differences between the microscopic morphology of yeasts and moulds?
Yeasts may have buds, capsules and germ tube production.
Moulds have hyphae, sexual spores or asexual conidia.
What is the term for fungal diseases in animals?
Mycoses.
These can be systemic/deep, cutaneous and subcutaneous.
What are the three domains of life?
Eukarya, bacteria, archaea
What are bacteria and archaea?
Prokaryotes-before nucleus
What is microbiology?
The study of micro organisms.
True or false, viruses are acellular?
True
True or false. Fungi and Protozoa are both eukaryotes?
True
What person used the term cells to describe the box-like structure he saw in cork tissue?
Robert Hooke.
Anton van Leeuwenhoek developed what?
High powered lenses
What did Louis Pasteur do?
Disproved spontaneous generation through development of S shaped flasks (kept microbes out).
What did Robert Koch do?
Established criteria necessary to prove causal relationship between a specific organism and disease (Kochs Postulate).
Describe the steps in Kochs postulate.
- Specific microorganism must be present in every case of the disease.
- Specific microorganism must be isolated and grown in pure culture.
- Inoculation of the pure culture must cause the disease in susceptible animals.
- The specific organism must be observed in and recovered from the experimentally diseased animal and its identity confirmed.
What were the limitations of Kochs postulate?
Noninfectious disease, mixed infections, uncultivable microbes, diseases with predisposing factors, diseases with carrier state, disease by opportunistic agent.
More holistic view is required in these situations - agent, host and environment.
Describe the characteristics of prokaryote cells.
DNA is a single molecule not in the nucleus. No nucleus.
No membrane bound organelles. Cell wall.
Usually
Describe the characteristics of a eukaryotic cell.
DNA in chromosomes in a nucleus. Membrane bound organelles. >10um diameter. Replicate by mitosis, gametes by meiosis. 80S and 70S ribosomes.
Membrane bound, no cell wall, mitochondria.
What is a cell envelope?
Cytoplasmic membrane surrounded by a rigid cell wall.
Membrane is phospholipids and proteins, semipermeable.
Wall is mainly peptoglycan, rigid, unique to prokaryotes.
What is an antigen?
Foreign molecule that induces an immune response.
Describe the structure of bacteria.
Prokaryotic cell. Cell envelope consisting of glycocalyx, cell wall and membrane. Cytoplasm with ribosomes. Nuclear material in centre. Flagellum and pilli may be present.
Bacteria divide by gram reaction on cell wall peptidoglycan. True or false?
True.
What are the differences between a gram positive and gram negative cell envelope?
Positive-2 layers, thick peptidoglycan, may have techoic aids.
Negative-3 layers, thin peptidoglycan, outer LPS(endotoxins and lipoproteins).
What are some forms of appendages that may be present on bacteria?
Capsule-streptococcus, anthrax, firm gelatinous coat of carbs and proteins, protective and antigenic. Outermost layer of cell.
Flagella-clostridia, thin long whip like structure, flagellin protein, motility.
Pilus/Fimbria-ecoli, gram negative, finer and shorter than flagella, pilin protein, adhesion, conjugation.
What is a bacterial specific form of nuclear material?
Plasmid.
Small, autonomous replicating circular DNA.
Can be shared between organisms via conjugation pilus.
If a bacterial cell has a ebdospore or spore present it is gram?…..
Positive
Describe the forms of bacterial identification.
Direct microscopic examination,
Culture (MATT, media, atmosphere, temp/humidity, time)
Immunological methods-serotyping, immunoassays.
Molecular methods-pcr
Phage typing
Describe the microscopic morphology of bacteria.
Size-0.2-2um wide, 1-5um long.
Shape and arrangement-Cocci or bacilli.
Gram reaction-positive or negative, determined by peptidoglycan.
Capsules or spores.
What are the different names of cocci arrangements?
Cocci(spherical) can be paired (diplo), chains(strepto), staphylococci(clusters), sarcinae(cubical).
What are the different forms of bacilli arrangement?
Bacilli (cylindrical) can be coccobacilli(short), fusiform(tapered ends), Filamentous, vibrio or spirella(curved).