Untitled Flashcard Set

What type of cells are fungi and what does that mean structurally?

Fungi are eukaryotic organisms, meaning they have a true nucleus and membrane-bound organelles.

What type of nutrition do fungi use?

Fungi are chemoheterotrophs, obtaining energy from chemical compounds and requiring organic nutrients.

How do fungi obtain nutrients differently than bacteria or animals?

Fungi secrete extracellular enzymes to break down complex molecules and then absorb nutrients.

What are the major components of fungal cell walls and membranes?

Cell wall: chitin, glucans, mannans; Cell membrane: ergosterol.

Where are fungi commonly found and what environments favor their growth?

Fungi are found in soil and water, preferring low moisture environments with acidic pH (~5).

Why are fungi important ecologically and medically?

Fungi act as decomposers, form mycorrhizae with plants, are used in food production, and can cause infections.

List key differences between fungi and bacteria.

Fungi are eukaryotic, have a nucleus, use chitin in their cell walls, and have ergosterol membranes. Bacteria are prokaryotic, lack a nucleus, use peptidoglycan in their cell walls, and do not contain ergosterol.

What are yeasts?

Yeasts are unicellular fungi, oval or spherical, and can be aerobic or facultative anaerobes.

How do yeasts reproduce?

Yeasts primarily reproduce asexually through budding or fission.

Describe the process of budding in yeast.

In budding, a parent cell forms a bud, the nucleus divides, one nucleus enters the bud, which then grows and eventually detaches.

What is an example of a yeast and why is it important?

Saccharomyces cerevisiae, used in baking and brewing, produces CO₂ and ethanol.

What are molds?

Molds are multicellular fungi with a filamentous structure made of hyphae.

What is a thallus?

The thallus is the entire body of a fungus, made of hyphae.

What are hyphae?

Hyphae are thread-like filaments that are the basic structural units of molds.

What is the difference between septate and coenocytic hyphae?

Septate hyphae have cross walls (septa) dividing the cells; coenocytic hyphae lack these walls and have a continuous cytoplasm.

What is a mycelium?

Mycelium is the mass of intertwined hyphae that forms the visible body of a fungus.

Difference between vegetative and aerial mycelium?

Vegetative mycelium grows in substrate to absorb nutrients; aerial mycelium grows above the surface and produces spores.

What are dimorphic fungi?

Dimorphic fungi exist in two forms: yeast form at 37°C (body) and mold form at 25°C (environment).

Why are dimorphic fungi important medically?

Many dimorphic fungi are pathogenic and can switch forms depending on the environment.

Example of dimorphic fungus?

Candida albicans is a common dimorphic fungus.

How do fungi reproduce asexually?

Fungi reproduce asexually through fragmentation and spore formation.

What are asexual spores?

Asexual spores are produced by one organism, genetically identical, and formed by mitosis.

What are the two main types of asexual spores?

Conidiospores (conidia) not in a sac and sporangiospores, which are formed in a sporangium.

List and describe types of asexual spores.

Arthroconidia: fragmented hyphae; Chlamydoconidia: thick-walled survival spores; Conidia: chains of non-enclosed spores; Blastoconidia: budding spores; Sporangiospores: formed inside sporangium.

What are sexual spores?

Sexual spores result from the fusion of two different fungal strains and increase genetic diversity.

What are the 3 stages of sexual reproduction in fungi?

Plasmogamy (cytoplasm fusion), Karyogamy (nuclei fuse to form diploid), Meiosis (produces haploid spores).

How are fungi classified?

Fungi are classified based on the type of sexual spores and morphology.

Characteristics of Zygomycota?

Zygomycota produce zygospores, have coenocytic hyphae, and include Rhizopus (black mold).

Characteristics of Ascomycota?

Ascomycota produce ascospores formed in sacs (ascus) and have septate hyphae.

Characteristics of Basidiomycota?

Basidiomycota produce basidiospores, have septate hyphae, and include mushrooms.

What are Microsporidia?

Microsporidia are fungi with no mitochondria, obligate intracellular parasites often seen in AIDS patients.

What is a mycosis?

A mycosis is a fungal infection that is usually chronic and slow-growing.

What are systemic mycoses?

Systemic mycoses are deep infections that affect organs and are caused by inhalation of spores.

What are subcutaneous mycoses?

Subcutaneous mycoses occur under the skin and enter through wounds, an example being Sporotrichosis.

What are cutaneous mycoses?

Cutaneous mycoses affect skin, hair, and nails, caused by dermatophytes which degrade keratin.

Are fungal infections contagious?

Most fungal infections are not contagious, except for cutaneous infections like ringworm.

What causes ringworm infections?

Ringworm infections are caused by dermatophytes, which are types of fungi, not worms.

How are ringworm infections transmitted?

Ringworm infections are transmitted by direct contact, contaminated objects, and infected hair/skin.

Common types of tinea infections?

Tinea pedis (athlete’s foot), Tinea corporis (body), Tinea cruris (jock itch), Tinea capitis (scalp), Tinea unguium (nails).

What are opportunistic mycoses?

Opportunistic mycoses occur in immunocompromised individuals where normally harmless fungi become pathogenic.

What is candidiasis (thrush)?

Candidiasis is caused by Candida albicans, affecting the mouth/genitals with symptoms of white patches and itching.

What causes overgrowth of Candida?

Overgrowth of Candida can be caused by antibiotics, immunosuppression, and pregnancy.

What is Aspergillosis?

Aspergillosis is a lung infection caused by Aspergillus, often seen as an opportunistic disease.

What is Pneumocystis jirovecii pneumonia (PCP)?

PCP is an opportunistic fungal pneumonia common in AIDS patients.

How do most antifungal drugs work?

Most antifungal drugs target ergosterol in fungal membranes, disrupting membranes and causing cell death.

Are fungal spores the same as bacterial endospores?

No, fungal spores are for reproduction, while bacterial endospores are for survival.

Are fungi prokaryotic or eukaryotic?

Fungi are always eukaryotic organisms.

Are fungi unicellular or multicellular?

Fungi can be both: yeasts are unicellular, while molds are multicellular.

What makes fungal infections increase in recent years?

The rise in immunocompromised patients and hospital-acquired infections are major factors.