Fungi (Lec. 11)

Question 1

Describe the general structure and function of the nucleus

Answer 1

Holds genetic material

Question 2

Describe the general structure and function of mitochondria

Answer 2

Powerhouse of the cell

Question 3

Describe the general structure and function of a chloroplast

Answer 3

Holds chlorophyll; does photosynthesis

Question 4

Describe the general structure and function of a ribosome

Answer 4

Synthesizes proteins

Question 5

Describe the general structure and function of the endoplasmic reticulum

Answer 5

Lots of layers; rough ER synthesizes proteins and smooth ER synthesizes lipids

Question 6

Describe the general structure and function of the golgi apparatus

Answer 6

Vesicle that packages things

Question 7

Describe the general structure and function of a lysosome

Answer 7

Digests waste

Question 8

Describe the general structure and function of the cytoskeleton

Answer 8

structure that helps the cell maintain its shape and internal organization

Question 9

Define fungi

Answer 9

Any group of spore-producing organisms feeding on organic matter; part of the Fungi kingdom

Question 10

Define yeast

Answer 10

A microscopic unicellular fungus; usually facultative anaerobes; that reproduce by budding and are capable of fermentation

Question 11

Define mold

Answer 11

Usually aerobic multicellular filamentous fungi

Question 12

Define thallus

Answer 12

An organism with no apical growth (not differentiated into stem and leaves or whatever); lacks true roots and a vascular system

Question 13

Define mycelium

Answer 13

The vegetative part of a fungus, consisting of a network of hyphae

Question 14

Define conidia

Answer 14

A spore in asexual or sexual reproduction that detaches from the parent and germinates into a new mold

Question 15

Define hypha

Answer 15

Long filament structures that absorb nutrients or are used for reproductive function

Question 16

Define ascus

Answer 16

A sac in which ascospores develop

Question 17

Define Ascospores

Answer 17

A sexually produced fungal spore from the phylum of Ascomycota that forms within an ascus

Question 18

Define Basidiospores

Answer 18

A sexually produced fungal spore from the phylum Basidiomycota

Question 19

Define Zygospores

Answer 19

A sexually produced fungal spore from the phylum Mucoromycota

Question 20

Does the fungal phylum Microsporidia have sexual spores?

Answer 20

No

Question 21

Define plasmogamy

Answer 21

The stage of fungal sexual reproduction in which one haploid nucleus (+) penetrates cytoplasm of another haploid recipient cell (-)

Question 22

Define karyogamy

Answer 22

The stage of fungal sexual reproduction in which two haploid nuclei fuse to form a diploid zygote

Question 23

Define mycosis

Answer 23

A fungal infection

Question 24

What are the five different types of mycoses (and describe)

Answer 24

Systemic mycoses: deep within the body, affecting tissues/organs
Subcutaneous mycoses: beneath the skin
Cutaneous mycoses: affect hair, skin, and nails
Superficial mycoses: localized (e.g. hair shafts)
Opportunistic mycoses: fungi harmless in normal habitat but pathogenic in a compromised host

Question 25

List the defining characteristics of fungi and differentiate them from bacteria

Answer 25

Fungi are heterotrophic eukaryotes that are vegetative and survive at more acidic conditions; can be facultative anaerobes or aerobic; are less susceptible to osmotic pressure and antibiotics.

Question 26

What are the four medically important phyla?

Answer 26

Mucoromycota, Microsporidia, Ascomycota, Basidiomycota

Question 27

Differentiate asexual from sexual reproduction and describe for each of the medically important phyla

Answer 27

Mucoromycota: asexual sporangiospores and sexual zygospores
Microsporidia: asexual sporangiospores and no sexual spores
Ascomycota: asexual conidiospores and sexual ascospores
Basidiomycota: asexual conidiospores and sexual basidiospores

Question 28

Describe the life cycle of a Mucoromycete

Answer 28

Asexual: A hypha produces a sporangium, which bursts to release sporangiospores. A sporangiospore germinates and produces hyphae; a vegetative mycelium grows. Sexual: Gametes form at the top of a hypha and plasmogamy occurs. A zygospore forms and karyogamy and meiosis occurs. The zygote produces a sporangium, which then releases spores, and the whole thing starts all over.

Question 29

Describe the life cycle of a Microsporidian

Answer 29

Only asexual reproduction: Sporangiospores are ingested or inhaled by an organism, and the spore injects a tube into the host cell. The spore’s cytoplasm and nucleus travels through the tube and into the host cell. The cytoplasm grows and the nuclei reproduce. The cytoplasm breaks up to form spores, which are then released by the cell.

Question 30

Describe the life cycle of an ascomycete.

Answer 30

Asexual: a hypha produces a conidiophore, and conidia are released form it. A conidium germinates to produce a hyphae; vegetative mycelium grows.
Sexual: from the mycelium, plasmogamy occurs, then karyogamy (an ascus forms), then meiosis then mitosis. The ascus opens to release ascospores, and the ascospores can germinate to produce hyphae.

Question 31

Describe the life cycle of a basidiomycete.

Answer 31

Asexual: A hyphal fragment breaks off vegetative mycelium, and the fragment grows to produce new mycelium.
Sexual: Plasmogamy occurs from the vegetative mycelium. A fruiting structure (“mushroom”) develops. Karyogamy occurs, and Basidia form diploid nuclei. Basidiospores are formed by meiosis, then they mature and are discharged. They can germinate and produce hyphae.

Question 32

Differentiate between yeasts, molds, and dimorphic fungi

Answer 32

Yeasts: nonfilamentous and unicellular. Budding yeasts divide unevenly and fission yeasts divide evenly.
Molds: multicellular filamentous fungi that are usually aerobic.
Dimorphic fungi grow as molds below 37 degrees C and as yeast above.

Question 33

Explain how hyphae and spores relate to fungal growth

Answer 33

Spores can germinate to make hyphae, which can grow to create mycelium.

Question 34

List the methods commonly used to identify fungal isolates in the lab

Answer 34

Colonial morphology, microscopic and macroscopic morphology. Immunological tests are very rare but there is a CSF antigen test for C. neoformans.