Mycology: Study of Yeasts, Molds, and Macrofungi

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Questions and Answers

What distinguishes fungi from other eukaryotes?

Rigid cell wall composed of chitin and glucan (correct)

Cell membrane with cholesterol as the major sterol component

Decomposition of animal and vegetable wastes

Presence of chlorophyll

Which component is present in the cell membrane of fungi?

Riboflavin

Ergosterol (correct)

Chlorophyll

Pectinase

What is the main function of fungi in obtaining some vitamins and enzymes?

Spoilage of food and foodstuffs

Obtaining antibiotics

Decomposition of animal and vegetable wastes (correct)

Obtaining fermented products

Which type of fungus is responsible for the production of Roquefort cheese?

Penicillium roqueforti Signup and view all the answers

What is the role of fungi in obtaining hormones?

Producing gibberellin in plants Signup and view all the answers

What is the main function of fungi in obtaining fermented products such as bread, wine, and beer?

Decomposition of animal and vegetable wastes Signup and view all the answers

What distinguishes the cell wall of fungi from that of bacteria?

Presence of chitin and glucan Signup and view all the answers

What is a common function of fungi in various diseases in humans, animals, and plants?

Producing antibiotics Signup and view all the answers

Where are fungi commonly found in nature?

In air, water, decomposing organic material Signup and view all the answers

Which structure is a virulence factor of Cryptococcus neoformans?

Capsule Signup and view all the answers

What is the primary function of chitin in the cell wall of fungi?

Gives shape and structure Signup and view all the answers

Which fungal form is characterized by smooth and creamy colonies on agar?

Yeasts Signup and view all the answers

What type of spore is formed by Aspergillus spp.?

Conidiospore Signup and view all the answers

In which condition do dimorphic fungi exist as yeast forms?

In the human body Signup and view all the answers

Which type of spore is found in large sacs at the ends of special hyphae in Penicillium spp.?

Sporangiospore Signup and view all the answers

What feature characterizes absolute pathogens among fungi?

They are capable of causing disease in both healthy and immunodeficient individuals. Signup and view all the answers

What is the primary characteristic of superficial mycoses caused by fungi?

Non-destructive and limited to superficial surfaces Signup and view all the answers

Which structure is targeted by antifungal drugs that have a toxic effect on fungal cells without harming human cells?

Ergosterol and zymosterol Signup and view all the answers

Which type of mycoses involve the deeper layers of the skin, including the cornea, muscle, and connective tissue?

Subcutaneous Mycoses Signup and view all the answers

How do most subcutaneous mycoses fungi access the deeper tissues?

By traumatic inoculation Signup and view all the answers

Which fungal species reproduce at 37°C, is found in pigeon feces, and shows CNS spread?

Cryptococcus neoformans Signup and view all the answers

What is the characteristic feature of the fungi exhibiting thermal dimorphism?

Exist as molds at 25°C and yeasts or spherules at 37°C Signup and view all the answers

What is the primary natural habitat for the class of Zygomycetes?

Soil and natural habitat Signup and view all the answers

Which agar is commonly used for culturing fungi?

Sabouraud dextrose agar (SDA) Signup and view all the answers

What method is used for microscopic examination of yeasts and pseudohyphae?

Gram stain Signup and view all the answers

Which test is used to detect cryptococcal antigen in blood or CSF?

% Latex agglutination test Signup and view all the answers

Which fungus is endemic in some ecological niches?

Histoplasma capsulatum Signup and view all the answers

Study Notes

Fungi vs. Other Eukaryotes

Fungi are distinct from other eukaryotes due to their cell walls made of chitin.
They absorb nutrients through external digestion, unlike many eukaryotes that ingest food.

Cell Membrane Component

Ergosterol is the key component present in the cell membrane of fungi.

Fungi and Vitamins/Enzymes

Fungi play a significant role in biosynthesis, aiding in the production of certain vitamins and enzymes.

Roquefort Cheese Production

Penicillium roqueforti is the type of fungus responsible for the production of Roquefort cheese.

Fungi and Hormones

Fungi contribute to hormone production by providing precursors and proteins necessary for metabolic functions.

Fermented Products

Fungi are essential in the fermentation process for products like bread, wine, and beer, primarily through yeast fermentation.

Fungal Cell Wall vs. Bacterial Cell Wall

Fungal cell walls are primarily composed of chitin, whereas bacterial cell walls contain peptidoglycan.

Role in Diseases

Fungi can act as opportunistic pathogens, causing various diseases in humans, animals, and plants.

Natural Habitat of Fungi

Fungi are commonly found in diverse environments, including soil, decaying organic matter, and as part of symbiotic relationships with plants.

Cryptococcus neoformans Virulence Factor

The capsule structure of Cryptococcus neoformans serves as a critical virulence factor.

Chitin Function

Chitin is responsible for providing structural support and protection in the cell wall of fungi.

Smooth and Creamy Colonies

Yeast forms produce smooth and creamy colonies when cultured on agar.

Aspergillus spp. Spores

Aspergillus spp. typically produce conidia, a type of asexual spore.

Dimorphic Fungi

Dimorphic fungi exist as yeast forms at body temperature (37°C).

Penicillium spp. Spores

Penicillium spp. produce ascospores found in large sacs known as asci at the ends of specialized hyphae.

Absolute Pathogens

Absolute pathogens among fungi can cause disease in healthy individuals and do not require pre-existing health issues.

Superficial Mycoses Characteristics

Superficial mycoses are characterized by infections limited to the outer skin layers or surface.

Target of Antifungal Drugs

Antifungal drugs commonly target ergosterol in the fungal cell membrane, reducing toxicity to human cells.

Deep Tissue Mycoses

Deep mycoses involve deeper layers of skin, muscle, and connective tissue, often leading to more severe infections.

Accessing Deep Tissues

Most subcutaneous mycoses fungi access deeper tissues through breaks in the skin or traumatic injuries.

Fungal Species Characteristics

Cryptococcus neoformans reproduces at 37°C, is found in pigeon feces, and can spread within the CNS.

Thermal Dimorphism

Fungi exhibiting thermal dimorphism can change form based on environmental temperature, showcasing different morphological traits.

Natural Habitat of Zygomycetes

The primary natural habitat for Zygomycetes is decaying organic matter and soil.

Culture Media

Sabouraud agar is commonly used for culturing fungi.

Microscopic Examination Method

The methylene blue staining method is used for microscopic examination of yeasts and pseudohyphae.

Cryptococcal Antigen Detection

The CrAg (cryptococcal antigen) test is used to detect cryptococcal antigen in blood or cerebrospinal fluid (CSF).

Endemic Fungi

Certain fungi are endemic to specific ecological niches, demonstrating specialized environmental adaptations.

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Description

Test your knowledge of mycology, the branch of science that investigates yeasts, molds, and macrofungi. Learn about the common occurrence of fungi in nature, their role in causing diseases, and the characteristics of these non-photosynthetic eukaryotic organisms.