Mycology

Question 1

Are fungi eukaryotes or prokaryotes?

Answer 1

They are Eukaryotes

Question 2

Describe the fungal nucleus.

Answer 2

True nucleus with nucleolus and nuclear membrane; Linear chromosome. Usually haploid

Question 3

Describe the fungal cytoplasm.

Answer 3

Contains eukaryotic ribosomes and organelles.

Question 4

Describe the fungal CM.

Answer 4

Differs from that of bacteria and plants; Contains Ergosterol as the dominant sterol instead of cholesterol.

Question 5

Describe the fungal cell wall.

Answer 5

Made of polysaccharides; Mannan, glucan and CHITIN
1. Mannoproteins: Found on surface, serologically specific
2.Glucans
3. Chitin: Long, unbranched chains of poly-N-acetylglucosamine, insoluble; provides support.
NO PG, glycerol/ribitol teichoic acids or LPS.

Question 6

Compare fungal growth rate to that of bacteria

Answer 6

Much slower; hours to bacteria’s minutes.

Question 7

What are the two types of fungal reproduction?

Answer 7

Asexual (Anamorph) and Sexual (Teleomorph)

Question 8

Describe fungal yeasts vs molds.

Answer 8

Yeasts: Unicellular, multiply by budding off blastoconidia
Molds: Multicellular, grow by making septate hyphae or aseptate hyphae.

Question 9

Describe the two types of asexual spores.

Answer 9

1. Sporangiospores: Produced in a containing sturcture.

2. Conidia: Arise directly from hyphae or are born on the conidiophore.

Question 10

Differentiate chlamydoconidia from arthroconidia.

Answer 10

1. Chlamydoconidia: Become larger than hyphae, round and thick walled. On terminal end of hyphae or along its course.
2. Arthroconidia: Conform to the shape of hyphal units.

Question 11

Discuss the 2 forms of thermally dimorphic fungi.

Answer 11

Yeast form: in an infected tissue

Mold form: Environmental resevoir

Question 12

Why is a culture the most important means of diagnosing fungal infections?

Answer 12

It is the most sensitive diagnostic tool.

Question 13

What does cycloheximide do once its added to a culture?

Answer 13

It inhibits the growth of yeasts and molds that may contaminate the specimen.

Question 14

What are the 4 classes of antifungal agents?

Answer 14

Polyenes, Azoles, Echinocanadins and Antimetabolites

Question 15

Describe polyenes and explain their MOA.

Answer 15

Unsaturated lipophilic lactone ring with a hydrophilic portion; Inhibits ergosterol synthesis.

1. Amphotericin B: Life threatening mycoses
2. Nystatin: Topical agent

Question 16

Describe Azoles and explain their MOA.

Answer 16

Azole rings; Inhibits conversion of lanosterol to ergosterol. Disrupts membrane synthesis. -suffix -azole

Question 17

Describe Echinocandins and explain their MOA.

Answer 17

Semisynthetic lipopeptides; Inhibits glucan synthesis. Suffix -fungin

Question 18

Describe Antimetabolites and explain their MOA.

Answer 18

A flourinated pyrimidine analogue; Inhibits synthesis of DNA, RNA and proteins. Flucytosine.