Chapter 12: Mycology

Question 1

Properties of Yeasts:

Answer 1

• Nonfilamentous
• Unicellular
• Budding Reproduction

Question 2

Dimorphic Fungi:

Answer 2

Yeast-like or mold-like depending on conditions.

Question 3

Fragmentation:

Answer 3

Asexual fungal growth

Question 4

Formation of Spores:

Answer 4

Sexual and asexual fungal growth

Question 5

Asexual Spore:

Answer 5

-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.

Question 6

Arthroconidia:

Answer 6

Fragmentation of hyphae results in the formation of arthroconidia in coccidiodes immitis.

Question 7

Blastoconidia:

Answer 7

Formed from the buds of a parent cell of candida albicans.

Question 8

Chlamydoconidia:

Answer 8

Thick-walled cells within hyphae of this candida albicans.

Question 9

Candida Albicans:

Answer 9

Pseudohyphae, clamydoconidia, blastoconidia.

Question 10

Zygomycota:

Answer 10

Rhizopus stolinifer: black bread mold.
asexual spores: sporangiospores
sexual spores: zygospores
Coenocytic

Question 11

3 Phases of Fungal Sexual Reproduction:

Answer 11

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).

Question 12

Life Cycle of a Zygomycete:

Answer 12

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.

Question 13

Zygospore:

Answer 13

Fusion of haploid cells produces one zygospore.

Question 14

Asexual Reproduction:

Answer 14

• Formed by hyphae of one organism.

- Germinated spore genetically identical to parent.

Question 15

Sexual Reproduction:

Answer 15

• Formed by fusion of nuclei from two opposite strains (+ and -)
• Germinated spore genetic traits of both parents.
• Happens less frequent than asexual reproduction.

Question 16

Meiosis Key points:

Answer 16

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.

Question 17

Anamorphs:

Answer 17

• Produce asexual spores only.
• Most are ascomycota, few basidiomycota.
• Penicillium sporothrix, stachybotrys, coccidioides, pneumocystis, candida albicans.

Question 18

Basidiomycota:

Answer 18

• Club fungi.
• Septate hyphae.
• Includes mushrooms.
• Produce basidiospores and sometimes conidiospores.

Question 19

Systemic Mycoses:

Answer 19

Deep within body.

Question 20

Subcutaneous Mycoses:

Answer 20

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.

Question 21

Cutaneous Mycoses:

Answer 21

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.

Question 22

Superficial Mycoses:

Answer 22

Localized, hair shafts.

-Limited to outermost layers of skin and hair.

Question 23

Opportunistic Mycoses:

Answer 23

Caused by normal microbiota or environmental fungi.

Question 24

-Histoplasmosis:

Answer 24

-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.

Question 25

Coccidioidomycosis:

Answer 25

• “Valley fever”
• Fragmentation of hyphae results in formation of arthroconidia.
• SW U.S. and New Mexico.

Question 26

Pneumocystis Pneumonia:

Answer 26

• Unknown what causes it, possibly human or soil transmission.
  Symptoms: Pneumonia.
  Treatment: Trimethoprim.

Question 27

Tinea Versicolor:

Answer 27

Dual pigmented ringworm on various places of the bodys’ skin.

Question 28

Tinea Manuum:

Answer 28

Ringworm on arms legs etc.

Question 29

Tinea corporis:

Answer 29

Ringworm on arms usually caused by pets.

Question 30

Tinea Capatis:

Answer 30

Ringworm on the head.

Question 31

Tinea Cruris:

Answer 31

Ringworm around gluteus maximus and crotch region.

Question 32

Tinea Barbae:

Answer 32

Ringworm around beard region of face.

Question 33

Sporotrichosis:

Answer 33

Gardener’s condition.

• Most common U.S. disease of the subcutaneous mycoses.
• Sporothrix schenchii enters puncture wound.

Question 34

Opportunistic Fungi:

Answer 34

Aspergillus fumigatus, candida, mucor, rhizopus.

-Predisposing factors weaken immune system making body more susceptible. (Cancer, diabetes, immunocompromised state).

Question 35

Candidiasis:

Answer 35

• Caused by candida albicans (yeast infection)
  -Can be on chest, orally, in eyes, buttocks.
  Greater risk with diabetes, obesity, antibiotic use, oral contraceptives, or pregnancy.

Question 36

How does the morphology of candida albicans contribute to the microbes pathogenicity?

Answer 36

Pseudohyphae

Question 37

How might the use of penicillin result in a case of candidiasis?

Answer 37

Imbalance of normal flora.

Question 38

Aspergillosis:

Answer 38

• Rare
• Asthmatic attacks and bronchitis.
• Pulmonary: balls of fungal elements in the lungs.
• Can invade other tissues and organs. Including inner ear, sinuses, and rarely eyes.

Question 39

Cryptococcosis:

Answer 39

Encapsulated yeast; not dimorphic.

• Inhaled from dust containing dried pigeon droppings.
• Leads to minor pulmonary infections and sometimes meningitis.

Question 40

Mycotoxins:

Answer 40

Toxin produced by fungi.

• Ergot poisoning: Claviceps purpurea: Saint anthony’s fire, LSD, migraines, hemorrhage/labor delivery.
• Leads to reduced blood in limbs.

Question 41

Aflatoxin Poisoning:

Answer 41

• Aspergillus flavus.
• Carcinogenic properties.
• Thought to be altered to a mutagenic compound in the human body.
• Leads to live cirrhosis and sometimes liver cancer.

Question 42

-Mycotoxicosis:

Answer 42

• Poisonous mushrooms called BASIDIOCARPS.

- Responsible for over 90 percent of human deaths from fungus poisoning.

Question 43

Trichothecenes:

Answer 43

• Inhibit protein synthesis in eukaryotic cells.

- Symptoms: Headaches, chills, nausea, vomiting, visual disturbances.