Mycology Flashcards
True or False
Fungi are eukaryotic
True
True or False
Fungal cells have a true nucleus with a surrounding membrane, and cell division is accompanied by mitosis or meiosis
True
True or False
Fungi have rigid cell walls with chitin and glucan as major components
True
True or False
Fungal cell membranes typically contain ergosterol
True
Where is chitin and glucan located?
Cell wall
Where is ergosterol located?
Cell membrane
True or False
Fungi are heterotrophic and requrie performed organic carbon compounds for their nutrition
True
What does Heterotrophic mean?
Lacking in chlorophyll
What does saprphytic mean?
nutrients from deas and decaying matter
True or False
Fungi secrete enzymes to break up large molecules-absorb nutrients
* can degrade cellulose and lignin (wood)
* Release CO2 and nitrogen compounsd into soil
True
What is saprophytic?
nutrients from dead and decaying matter
What are some of the significance of fungi?
- decompose dead organisms and recycle their nutrients
- help plants absorb water and minerals
- used for food
- produce antibiotics
- research tools
What is the morphology of fungi?
- Two basic body shapes: molds and yeasts
- some fungi are dimorphic
What is the difference between molds and yeast?
Molds
* composed of long filaments called hyphae
* multicellular
Yeasts
* small, globular, and composed of a single cell
* reproduce by mitosis or budding
Yeast reproduction under a microscope look like a tiny snowman.
What does it mean to be dimorphic?
- produce both yeastlike and moldlike shapes
- change in response to environmental conditions
How do fungi reproduce?
by spores
How do fungi reproduce through spores?
through mitosis (asexual process)
asexual spores and spore-bearing structures are designed to ensure repid dispersal to new habitats
How to identify yeast?
- colonial morphology
- microscopic morphology
- biochemical testing DNA sequencing
Candida albicans
a yeast
- “feet”-like extensions commonly seen on blood agar
- terminal, thick-walled chlamydospores
- Blastoconidia clustered at septa
Cryptococcus neoformans
a yeast
- cream-colored, mucoid colonies
- direct India Ink wet mount of CSF
Hyphae
- rigid cell wall
- increases in length b/c of apical growth with mitotic cell division
- in higher fungi, hyphae are divided into cells by the development of cross-walls (septa)
structure of hyphae
- looks like a tree branch
- the base of the branch is the septum
- apical growth is straight up
- hyphae are the little branches
Mycelium morphology
Vegetative
* penetrates into the medium to absorb nutrients
Aerial
* produces spores (conidia), pigmentation, texture and topography
What is the taxonomy and classification of fungi?
- Division Chytridiomycota
- Division Zygomycota +
- Division Ascomycota +
- Division Basidiomysota +
+ contains species pathogenic to humans
What are clinical groupings for fungal infections?
- Cutaneous Mycoses
- Subcutaneous Mycoses
- Opportunistic Systemic Mycoses
- Dimorphic Systemic Mycoses
What is cutaneous mycoses?
- Superficial fungal infections of the skin, hair or nails
- No living tissue invaded
- Pathological changes are elicited due to presence of the infectious agent and its metabolic products.
ringworm
What is the causative organisms of Dermatophytosis?
cutaneous mycoses
Ringworm of the scalp, skin & nails
Dermatophytes (Microsporum, Trichophyton, Epidermiphyton)
What is the causative organisms of Candidiasis?
Cutaneous Mycoses
skin, mucous membranes & nails
Candida albicans and related species
What are subcutaneous mycoses?
- Chronic localized infections of the skin and subcutaneous tissue following the traumatic implantation of the etiologic agent
- Causative fungi are soil saprophytes.
- Ability to adapt to the tissue environment and elicit disease is extremely variable.
rose gardeners disease
What are opportunistic systemic mycoses?
- Fungal infections which occur in debilitated patients whose normal defense mechanisms are impaired
- Involve fungi with a very low inherent virulence
- Increased incidence parallels more aggressive cancer & post transplantation chemotherapy and the emergence of AIDS
What are the pigmentation of molds?
- dematiaceous
- hyaline
What are dimorphic systemic mycoses?
- Fungal infections caused by dimorphic pathogens which can overcome the physiological and cellular defenses of the normal human host by changing their morphological form
- Environmental form – filamentous or hyphal
- Tissue form – yeast or yeast like
- Primary site of infection – pulmonary
- Geographically restricted
