Chapter 12: Mycology Flashcards
Properties of Yeasts:
- Nonfilamentous
- Unicellular
- Budding Reproduction
Dimorphic Fungi:
Yeast-like or mold-like depending on conditions.
Fragmentation:
Asexual fungal growth
Formation of Spores:
Sexual and asexual fungal growth
Asexual Spore:
-Formed by hyphae of one organism.
-Spore is genetically identical to parent cell.
-Not enclosed in sac: Conidiophore
Conidiospore (Arthoconidia, blastoconidia, chlamydoconidia).
- Enclosed in sac: Sporangiophore, sporangium, sporangiospore.
Arthroconidia:
Fragmentation of hyphae results in the formation of arthroconidia in coccidiodes immitis.
Blastoconidia:
Formed from the buds of a parent cell of candida albicans.
Chlamydoconidia:
Thick-walled cells within hyphae of this candida albicans.
Candida Albicans:
Pseudohyphae, clamydoconidia, blastoconidia.
Zygomycota:
Rhizopus stolinifer: black bread mold.
asexual spores: sporangiospores
sexual spores: zygospores
Coenocytic
3 Phases of Fungal Sexual Reproduction:
1: Plasmogamy: haploid donor cell nucleus (+) penetrates cytoplasm of recipient cell (-).
2. Karyogamy: + and - nuclei fuse
3. Meiosis: diploid nucleus produces haploid nuclei (sexual spores).
Life Cycle of a Zygomycete:
1) Aerial hypha produce sporangium.
2) Sporangium bursts to release spores.
3) Spore germinates to produce hyphae.
4) Vegetative mycelium grows.
5) Gametes form at tip of hypha.
6) Plasmogamy.
7) Zygospore forms.
8) Karyogamy and meiosis.
9) Zygote produce a sporangium.
10) Spores are released from sporangium.
11) Spore germinates to produce hyphae.
Zygospore:
Fusion of haploid cells produces one zygospore.
Asexual Reproduction:
- Formed by hyphae of one organism.
- Germinated spore genetically identical to parent.
Sexual Reproduction:
- Formed by fusion of nuclei from two opposite strains (+ and -)
- Germinated spore genetic traits of both parents.
- Happens less frequent than asexual reproduction.
Meiosis Key points:
Hypha are haploid
Karyogamy yields diploid cells
Therefore, they must go through meiosis to get back to a haploid state before going through mitosis to make spores.
Anamorphs:
- Produce asexual spores only.
- Most are ascomycota, few basidiomycota.
- Penicillium sporothrix, stachybotrys, coccidioides, pneumocystis, candida albicans.
Basidiomycota:
- Club fungi.
- Septate hyphae.
- Includes mushrooms.
- Produce basidiospores and sometimes conidiospores.
Systemic Mycoses:
Deep within body.
Subcutaneous Mycoses:
Beneath the skin.
Involve dermis, subcutaneous tissue, muscles, fascia, and bone.
-Lesions develop at site of trauma.
-Extends epidermis.
-Difficult to treat, often requires surgical intervention.
Cutaneous Mycoses:
Affect hair, skin, and nails. -Trichophyton: hair, skin, and nails. -Epidermophyton: skin and nails. -Microsporum: hair and skin Signs and Symptoms: -Skin: itchy scaly ring lesions. -Nails: Flaky, patchy, discolored nails. Hair- Balding patches.
Superficial Mycoses:
Localized, hair shafts.
-Limited to outermost layers of skin and hair.
Opportunistic Mycoses:
Caused by normal microbiota or environmental fungi.
-Histoplasmosis:
-Airborne spores.
-Midwest U.S.
-Pathogen: Histoplasma capsulatum.
-Asymptomatic in most cases.
-Symptoms resemble TB.
Coughing with bloody sputum.
-Lesions in most organs.
-Yeastlike form found inside macrophages.