Pg. 13-16.8

What are two types of fungi?

Yeasts and molds 

What is the study of fungi called?

Mycology = study of fungi (fungi vs bacteria Table 12.1)

What is a disease caused by fungi called?

Mycosis = any disease caused by a fungus

How many fungi are pathogenic to humans and animals?

About 200 are pathogenic to humans and animals, and still at least 200,000 waiting to be discovered.

Are fungal diseases chronic or acute?

The human diseases produced by fungi tend to be chronic and slow to develop.

What type of nutrition do fungi use?

Chemoheterotroph

Whats the food aquisition method for fungi?

They’re absorptive

The cellular arrangement of different fungi is:

• Unicellular → yeasts

• Filamentous → molds

• Fleshy → mushrooms

How do fungi obtain nutrients?

They are absorptive organisms.

What types of spores do fungi produce? Does fungi have embryo formation?

Sexual and asexual spores, No.

Do fungi have locomotion?

None — all are nonmotile.

What do fungal cell walls contain?

Glucans, mannans, and chitin (polysaccharides)

Are fungi prokaryotic or eukaryotic?

Eukaryotic

What type of nutrition do fungi exhibit?

Chemoheterotrophs: parasitic or saprophytic

Are fungi single-celled or multicellular?

Both, only yeasts are unicellular

Are fungi aerobic or anaerobic?

Aerobic (almost all molds) or facultative anaerobic (most yeasts)

What is the general structure of most fungi?

They usually have a filamentous (threadlike) structure.

What are fungal threads called?

Hyphae (singular: hypha)

What are the two kinds of hyphae?

Septate and aseptate (coenocytic)

What is mycelium?

The mass of hyphae that makes up the body of a mold.

What is dimorphism in fungi?

The ability to exist in two forms:

- Yeast form in the animal host (at 37°C)

- Mold form in soil (at 25°C)

Do all fungi produce spores?

Yes, all produce spores, usually two kinds.

How are sexual spores formed?

By the fusion of two cells (various mating processes).

How are asexual spores formed?

By cell division (mitosis).

How are fungi usually identified?

By their spore type.

What is a mold?

A fungus that grows as a mass of loose hyphae.

What is systemic mycosis?

A deep fungal infection that occurs within the body.

What is subcutaneous mycosis?

A fungal infection that occurs beneath the skin.

What is cutaneous mycosis?

A fungal infection that affects hair, skin, and nails.

What is superficial mycosis?

A fungal infection that is localized, for example, in hair shafts.

What is opportunistic mycosis?

A fungal infection caused by normal microbiota or environmental fungi, usually in individuals with weakened immune systems.

What is Rhizopus spp.?

Common bread molds.

What type of hyphae does Rhizopus have?

Aseptate hyphae.

What type of asexual spores does Rhizopus produce?

Sporangiospores, which are contained in a sporangium (spore case).

What type of sexual spores does Rhizopus have?

Zygospores.

What type of pathogen is Rhizopus in immunosuppressive patients?

An opportunistic pathogen.

What is Penicillium spp.?

Common decay organisms and a source of antibiotics.

What type of hyphae does Penicillium have?

Septate hyphae.

What type of asexual spores does Penicillium produce?

Conidia — naked spores in chains.

What type of sexual spores does Penicillium produce?

Ascospores, found in a sac (ascus).

What kind of patients can Penicillium cause fatal diseases in?

AIDS patients.

What is Aspergillus sp.?

A common decay organism and occasional pathogen.

What type of hyphae does Aspergillus have?

Septate hyphae.

What type of asexual spores does Aspergillus produce?

Conidia — naked spores in chains.

What type of sexual spores does Aspergillus produce?

Ascospores in a sac (ascus).

What are predisposing factors for Aspergillus infection?

An impaired immune system, cancer, and diabetes.

What disease does Aspergillus cause?

Aspergillosis, an airborne opportunistic disease of the lungs.

What disease is caused by Coccidioides immitis?

Coccidioidomycosis (Valley fever) — a respiratory infection. (Pg. 713)

Where is Coccidioides immitis commonly found?

In hot, dry valley areas.

What type of fungus is Coccidioides immitis?

A dimorphic fungus.

How does Coccidioides immitis grow in soil?

Its arthroconidium germinates tubular hypha in soil.

How is Coccidioides immitis transmitted?

Through airborne spores.

What structure forms in the lungs during infection with Coccidioides immitis?

A spherule — a thick-wall body filled with spores.

What percentage of Coccidioides immitis cases become systemic?

About 1% of cases become systemic (disseminated) infection.

What are yeasts?

Fungi that are non-filamentous single cells, typically spherical or oval.

How do yeasts reproduce?

By budding or fission.

What is Saccharomyces spp.?

Baking and brewing yeasts.

What is Candida albicans?

A common pathogen causing candidiasis, vaginitis (“yeast infection”), and thrush (P. 608).

Where is Candida albicans found normally?

In the normal flora.

What causes infections by Candida albicans?

An opportunistic overgrowth of Candida.

Who is most at risk for Candida albicans infections?

Infants, HIV-infected patients, diabetics, or those who have used antibiotics.

What is the fungal form of Candida albicans that increases its pathogenicity?

It is a dimorphic fungus that forms pseudohyphae (Fig. 21.17a, P.609); in this form, Candida is resistant to phagocytosis.

What does Cryptococcus neoformans cause?

It is a yeast-like pathogen that can cause fungal infections. (P. 639)

What disease is caused by Cryptococcus neoformans?

Causes cryptococcosis, an infection of the lungs that can disseminate to the central nervous system, causing meningitis with a high mortality rate.

How does Cryptococcus neoformans reproduce?

By budding.

Is Cryptococcus neoformans dimorphic?

Yes, it also forms hyphae and reproductive spores, making it dimorphic.

How is Cryptococcus neoformans transmitted?

Mainly by inhalation of dried, contaminated bird droppings and soil.

What structure helps protect Cryptococcus neoformans?

It has a heavy polysaccharide capsule.

What is Pneumocystis jiroveci?

Once classified as a protozoan, but analysis of rRNA indicates it is closely related to certain yeasts.

Is Pneumocystis jiroveci unicellular or multicellular?

Unicellular

What disease is caused by Pneumocystis jiroveci?

Pneumocystis pneumonia in HIV patients and immunosuppressed individuals.

What is found in the sputum samples of patients infected with Pneumocystis jiroveci?

Cysts, each containing eight developing parasites.

Where can the life cycle of Pneumocystis jiroveci be found?

In Fig. 24.19, Page 714.

What are lichens composed of?

Two organisms living in close association: a fungus and an alga.

What type of relationship do the fungus and alga in lichens have?

A mutualistic relationship.

What does the alga provide in the lichen relationship?

The alga photosynthesizes, providing carbohydrates for the lichen.

What does the fungus provide in the lichen relationship?

The fungus provides a holdfast for attachment.