Medical Mycology Lecture 1
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Questions and Answers

Which characteristic is NOT true about fungi?

  • All fungi are prokaryotic organisms. (correct)
  • Most fungi have a simple structure and are microscopic.
  • Fungi are heterotrophic and do not contain chlorophyll.
  • The cell wall of fungi is made up of chitin.

What type of nutritional strategy do fungi utilize?

  • Autotrophic photosynthesis
  • Saprobic, symbiotic, and parasitic (correct)
  • Chemosynthesis
  • Filter feeding

Which type of cellular structure do fungi possess?

  • Flexible cell membrane with no cell wall
  • Rigid cell wall made of peptidoglycan
  • No distinct cell wall structure
  • Rigid cell wall made of chitin and complex carbohydrates (correct)

What makes fungi heterotrophic organisms?

<p>They require organic material to obtain nutrients. (B)</p> Signup and view all the answers

Which of the following statements about fungi is accurate?

<p>Fungi can be saprobic, which means they feed on dead organic matter. (D)</p> Signup and view all the answers

What is the main characteristic of septate hyphae?

<p>They are divided into cells by cross-walls called septa. (C)</p> Signup and view all the answers

What term is used to refer to the cross-walls that divide septate hyphae?

<p>Septa (B)</p> Signup and view all the answers

Which of the following best describes nonseptate hyphae?

<p>They are also known as coenocytic hyphae. (D)</p> Signup and view all the answers

How do septate and nonseptate hyphae differ fundamentally?

<p>Septate hyphae are divided by septa, while nonseptate hyphae are not divided. (A)</p> Signup and view all the answers

Which statement is false regarding hyphae?

<p>All hyphae are primarily found in terrestrial fungi. (C)</p> Signup and view all the answers

What type of hyphae are described as not being divided by septa?

<p>Coenocytic hyphae (B)</p> Signup and view all the answers

What is the term used to describe the interwoven hyphae that form the body of fungi?

<p>Mycelium (D)</p> Signup and view all the answers

What characterizes dimorphic fungi?

<p>Their form changes based on temperature. (B)</p> Signup and view all the answers

At what temperature do dimorphic fungi typically occur in mold form?

<p>25°C to 30°C (B)</p> Signup and view all the answers

Which of the following statements about non-septate hyphae is true?

<p>They contain multiple nuclei. (C)</p> Signup and view all the answers

What term is used to describe fungi that do not reproduce sexually or whose sexual reproduction is not known?

<p>Imperfect fungi (B)</p> Signup and view all the answers

What structure is responsible for the production of ascospores?

<p>Asci (A)</p> Signup and view all the answers

What is the mode of reproduction for fungi classified as anamorphs?

<p>Asexual reproduction (B)</p> Signup and view all the answers

Which of the following groups of fungi is primarily known for not having a known sexual reproduction mechanism?

<p>Deuteromycetes (A)</p> Signup and view all the answers

In which structure are ascospores specifically produced?

<p>Ascus (A)</p> Signup and view all the answers

What type of hyphae do molds in Mastigomycota possess?

<p>Non-septate hyphae (D)</p> Signup and view all the answers

How do Mastigomycota obtain their nutrients?

<p>Absorptive nutrition (A)</p> Signup and view all the answers

Which of the following describes the classification of Mastigomycota?

<p>Flagellated, motile fungi (B)</p> Signup and view all the answers

Which statement is true about Mastigomycota?

<p>They can include both yeast and mold forms. (A)</p> Signup and view all the answers

What type of organism can Mastigomycota NOT be classified as?

<p>Photosynthetic plant (C)</p> Signup and view all the answers

Which class of fungi includes organisms such as Phytophthora?

<p>Oomycetes (A)</p> Signup and view all the answers

Which of the following classes of fungi is known for its non-motile characteristics?

<p>Plasmodiophoromycetes (B), Oomycetes (D)</p> Signup and view all the answers

Which class does not primarily contain organisms like molds or yeasts?

<p>Chytridiomycetes (A)</p> Signup and view all the answers

Which class of fungi includes neither yeasts nor filamentous molds?

<p>Hyphochytridiomycetes (B)</p> Signup and view all the answers

Which of the following classes would be least likely to be involved in pathogenic interactions with plants?

<p>Hyphochytridiomycetes (C)</p> Signup and view all the answers

Flashcards

Fungi Characteristics

Fungi are eukaryotic organisms that are heterotrophic and do not contain chlorophyll.

Fungi Nutrition Types

Fungi can be saprobic (feed on decaying matter), symbiotic (live in a beneficial relationship with another organism), or parasitic (live on or in a host and harm it).

Fungi Cell Walls

Fungi cells have rigid cell walls made of chitin and complex carbohydrates like chitosan, mannan, glucan and galactomannan.

Fungi Structure

Fungi typically have a simple structure and are mostly microscopic.

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Fungi Eukaryotic

Fungi are composed of eukaryotic cells having a nucleus and other membrane-bound organelles.

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Septate hypha

A hypha divided into cells by cross-walls called septa.

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Nonseptate hypha

A hypha without cross-walls, also called a coenocytic hypha.

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Septa

Cross-walls that divide hyphae into cells.

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Hypha

A filamentous structure forming the body of a fungus.

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Coenocytic hypha

A continuous hypha without cross walls; many nuclei in one cell.

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Mycelium

The interwoven mass of hyphae in a fungus.

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Dimorphic fungi

Fungi that can exist in two different forms depending on temperature.

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Mold form of fungi

A filamentous growth form of certain fungi seen in culture media at temperatures between 25°C - 30°C.

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Ascospores

Spores produced within bag-like structures called asci, which are involved in the sexual reproduction of some fungi.

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Asci

Bag-like structures within fungi that contain ascospores, responsible for sexual reproduction.

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Anamorph

Asexual reproductive phase in fungi, where reproduction doesn't involve the fusion of gametes.

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Imperfect Fungi

Fungi whose sexual reproduction has not been observed or is unknown, sometimes called Deuteromycetes.

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Deuteromycetes

A group of fungi that lack a known sexual reproductive stage, often referred to as 'imperfect fungi'.

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Mastigomycota

A group of fungi with flagellated, motile cells. They can be either yeast-like or mold-like. If mold-like, they have non-septate hyphae. They have cell walls and obtain nutrients through absorptive nutrition.

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Absorptive nutrition

Obtaining nutrients by secreting enzymes that break down food outside the organism and then absorbing the digested molecules.

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Yeast-like Mastigomycota

Members of the Mastigomycota group that are unicellular and often reproduce by budding. Similar to typical yeasts but with flagella.

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Mold-like Mastigomycota

Members of the Mastigomycota group that form filamentous structures (hyphae) and often reproduce by spores. With non-septate hyphae.

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Chytridiomycetes

A class of fungi with flagellated spores, mostly aquatic, and known for some parasitic species affecting plants and animals.

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Hyphochytridiomycetes

A class of fungi with flagellated spores, closely related to chytrids but with a distinct cell wall structure and mostly found in aquatic environments.

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Plasmodiophoromycetes

A class of parasitic fungi that form plasmodia (multinucleate masses of cytoplasm) inside host cells, mainly affecting plants, causing root diseases and stunting.

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Oomycetes

A class of fungal-like organisms with a distinctive cell wall structure (cellulose) and are often responsible for plant diseases like downy mildew and late blight.

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Phythium and Phytophthora

Important genera in Oomycetes, causing significant plant diseases like damping off and root rot in seedlings, and blight in crops. These are important to recognize due to their impact on food security.

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Study Notes

Medical Mycology Lecture 1

  • Medical mycology is the study of fungi as agents of disease.
  • Basic Mycology:
    • Fungi are eukaryotic organisms.
    • Fungi are heterotrophic—they cannot produce their own food.
    • Fungi have a rigid cell wall composed of chitin and complex carbohydrates (e.g., chitosan, mannan, glucan, galactomannan).
    • Most fungi have simple, microscopic structures.
    • Fungi reproduce asexually or sexually through spore formation, budding, and hyphal extension.
    • Fungi can be saprophytic, parasitic, or symbiotic.
    • Saprophytic fungi obtain nutrients from dead organic matter.
    • Parasitic fungi obtain nutrients from living organisms.
    • Symbiotic fungi live in a mutually beneficial relationship with another organism.

Structure of Fungi

  • Unicellular Fungi (Yeasts):

    • Typically spherical or oval.
    • Yeast cells retain their individuality.
    • Examples include Saccharomyces cerevisiae and Candida albicans.
    • Yeast-like: elongated cells attach to each other side-by-side forming pseudohyphae.
    • Form smooth, creamy, bacterial-like colonies in culture media.

  • Filamentous Fungi (Molds):

    • Multicellular fungi composed of long, tubular filaments called hyphae.
    • Hyphae (sing. hypha).
    • Septate hyphae: divided into cells by cross-walls (septa).
    • Non-septate (coenocytic) hyphae: not divided by septa.
    • Interwoven hyphae form a mass called mycelium.
    • Examples include Aspergillus, Penicillium, and Rhizopus.

Dimorphic Fungi

  • Some fungi exhibit dimorphism, meaning they can exist in two forms depending on environmental conditions.
  • In culture media (temperatures 25°C–30°C): appear as molds.
  • In infected tissues (temperatures 35°C–37°C): appear as yeasts.

Reproduction in Fungi

  • Asexual Reproduction:

    • Budding (in yeasts).
    • Hyphal fragmentation (in molds).
    • Asexual spore formation: - Spores produced within a saclike structure (sporangium), known as sporangiospores. - Spores that are not produced within a sporangium, and found on hyphae or conidiophores, are called conidia (sing. conidium).

  • Sexual Reproduction:

    • Involves fusion of specialized cells and typically produces resistant spores.
      • Spores are named according to the method for their production.
        • Zygospores produced by the fusion of morphologically identical cells. Example Rhizopus
        • Oospores produced by the fusion of morphologically different cells.
        • Ascospores produced within saclike structures called asci (sing. ascus).
    • Anamorph: Asexual reproduction form; sometimes referred to as imperfect fungi (e.g., Aspergillus, Fusarium, Candida).
    • Teleomorph: Sexual reproduction form.
    • Some fungi produce both sexual and asexual forms = Perfect fungi.

Classification of Fungi

  • Taxonomy of fungus are based on morphological, physiological, genetic, and molecular characteristics.
  • Fungi are classified into three major divisions based on their structure and lifestyle.
    • Gymnomycota, Mastigomycota, and Amastigomycota

Clinical Classification of Fungi

  • Fungal infections (mycoses) are categorized based on the location of infection in the body.
    • Superficial mycoses
    • Cutaneous mycoses
    • Subcutaneous mycoses
    • Systemic mycoses
    • Opportunistic mycoses

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Description

This quiz covers the fundamental aspects of medical mycology, focusing on the role of fungi as agents of disease. It explores the structure, reproduction, and nutritional modes of fungi, including saprophytic, parasitic, and symbiotic relationships. Gain insights into unicellular fungi such as yeasts and their significance in medical contexts.

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