Fungi and Lichen (MB)

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Questions and Answers

What is the estimated number of potential fungal species?

1,500,000

Which group does Saccharomyces cerevisiae belong to?

Ascomycota

When did the last common ancestor of fungi exist?

500 million years ago

Which group includes typical mushrooms and plant pathogens?

Basidiomycota Signup and view all the answers

Which of the following is true about fungal dimorphism?

It allows fungi to evade host defenses by residing within phagocytotic cells. Signup and view all the answers

What is the primary consequence of failure to switch dimorphically in fungi?

Reduction in pathogenicity Signup and view all the answers

What are the causes of fungal diseases?

Inappropriate immune response, toxin production, and host infection Signup and view all the answers

Which group of fungi is the largest and most diverse?

Ascomycota Signup and view all the answers

What is the size of Saccharomyces cerevisiae, a unicellular fungus?

Around 6 µm in diameter Signup and view all the answers

What are Microsporidia?

Ancient groups of parasitic or saprophytic fungi Signup and view all the answers

What is a characteristic feature of Microsporidia spores?

Small and non-motile Signup and view all the answers

What do pathogenic fungi switch between?

Multicellular hyphae and single-celled yeasts Signup and view all the answers

What is the primary role of fungi in the ecosystem?

Recyclers Signup and view all the answers

What are the recommended tasks for further study mentioned in the text?

Reading specific sections of Brock Biology of Microorganisms, exploring Candida albicans as a nosocomial pathogen, and understanding its growth, size, cell shape, and treatment options Signup and view all the answers

What is the primary role of yeasts in food processing?

Fermentation of fruits to produce wines and cereals to make beer Signup and view all the answers

What is the composition of the rigid cell wall of fungi?

Chitin and glucan Signup and view all the answers

How do fungi primarily obtain their nutrients?

By secreting enzymes to digest polymeric materials Signup and view all the answers

What is the function of conidia in fungi?

Dispersal to new habitats Signup and view all the answers

What is the purpose of mycorrhizal fungi in relation to plants?

Facilitate the uptake of nutrients from the soil Signup and view all the answers

What is the primary role of sexual spores in fungi?

Reproduction and genetic variation Signup and view all the answers

What is the main reason for dimorphic switching in fungi?

Response to the host environment and pathogenicity Signup and view all the answers

What is the characteristic morphology of most fungi?

Multicellular with a network of hyphae Signup and view all the answers

What is the primary method of asexual reproduction in fungi?

Asexual production of conidia Signup and view all the answers

What are the three broad categories of ways fungi obtain their food?

Parasite, Symbiotic relationship, Saprophyte Signup and view all the answers

What is the role of filamentous fungi in traditional food processes?

Ripening of cheeses and production of enzymes Signup and view all the answers

What was the first antibiotic derived from a fungus?

Penicillium rubens (Penicillium notatum) Signup and view all the answers

What is the size range of Microsporidia spores?

1-5um Signup and view all the answers

What is the composition of the inner wall (endospore) of Microsporidia spores?

Chitin Signup and view all the answers

How do Microsporidia spores infect host cells?

By extending a helical polar tubule and injecting sporoplasm into the host cell Signup and view all the answers

Which class of fungal infections is the most serious?

Systemic Signup and view all the answers

What is the primary challenge in treating systemic fungal infections?

Toxicity of fungal treatments Signup and view all the answers

What makes treatment of systemic fungal infections difficult?

Toxicity of fungal treatments Signup and view all the answers

Which mechanism of fungal infection is referred to as mycosis?

Host infection Signup and view all the answers

Which of the following fungi is commonly used in traditional food processes?

Aspergillus Signup and view all the answers

Which fungus is known as baker’s yeast?

Saccharomyces cerevisiae Signup and view all the answers

Which group of fungi contains both single-celled and filamentous species?

Ascomycota Signup and view all the answers

What is the primary method by which fungi obtain their nutrients?

Saprophyte, by using dead or dying organisms as a food source Signup and view all the answers

What is the primary characteristic of fungi in relation to their nutritional requirements?

They have simple nutritional requirements and can secrete enzymes to digest polymeric materials Signup and view all the answers

What type of relationship does lichen exemplify in terms of obtaining nutrients?

Symbiotic relationship, by providing protection and moisture in return for nutrients from an organism capable of photosynthesis Signup and view all the answers

What is the primary role of the mycobiont in the lichen symbiosis?

Providing structure and branching growth for the lichen Signup and view all the answers

What is the main function of the photobiont in the lichen symbiosis?

Conducting photosynthesis to produce energy for the lichen Signup and view all the answers

What is the main visible body of the lichen called?

Thallus Signup and view all the answers

What is the categorization based on structural characteristics of lichen growth forms?

Fruticose, Foliose, Squamulose, Crustose Signup and view all the answers

What is the composition of the uppermost layer of the stratified lichen thallus?

Pruina layer of inorganic deposits Signup and view all the answers

What is the primary characteristic of the mycobiont's morphology in lichens?

Fungal hyphae branch growth at tip Signup and view all the answers

What is the primary role of the thallus morphology in lichens?

Influencing by the mycobiont species Signup and view all the answers

What is the third partner in the lichen symbiosis referred to as?

Tripartite Signup and view all the answers

Which layer do crustose lichens attach to directly?

Medulla layer Signup and view all the answers

How do fruticose lichens attach to surfaces?

Via rhizines Signup and view all the answers

What is the primary role of lichenized fungi?

Heterotrophic, requiring organic carbon Signup and view all the answers

What percentage of lichens form 3D structures such as foliose or fruticose?

25% Signup and view all the answers

What do photobionts require for photosynthesis?

Light, water, and carbon dioxide Signup and view all the answers

What is the primary function of lichens as carbon sinks?

Assimilating CO2 during photosynthesis Signup and view all the answers

What is the role of the cyanobacterial partner in lichen symbiosis?

Responsible for nitrogen fixation Signup and view all the answers

What is the significance of lichens as bioindicators?

Identifying patterns of air pollution Signup and view all the answers

What is the primary role of lichens in relation to air pollution?

Serving as bioindicators Signup and view all the answers

What is the primary role of lichens in relation to carbon dioxide?

Acting as carbon sinks Signup and view all the answers

What is the primary role of the medulla layer in lichen structure?

Supporting the photobiont Signup and view all the answers

Study Notes

Fungal Dimorphism, Disease Classes, and Microsporidia

Dimorphism in fungi allows them to evade host defenses by residing within phagocytotic cells, shielding them from the immune system
Failure to switch dimorphically almost always reduces pathogenicity in fungi
Fungal diseases are caused by inappropriate immune response, toxin production, and host infection (mycosis) with systemic infections being the most serious
Ascomycota is the largest and most diverse group of fungi, containing single-celled species, filamentous species, and yeasts like Candida albicans
Saccharomyces cerevisiae is a unicellular fungus, around 6 µm in diameter, studied for basic research and used in biotechnical applications
Microsporidia are ancient groups of parasitic or saprophytic fungi, closely related to fungi, and infect every vertebrate and invertebrate
Microsporidia have the smallest genome size of eukaryotes, infect a wide range of hosts, and have three common species that infect humans
Symptoms of Microsporidia infection include chronic, non-bloody diarrhea and respiratory infections, particularly affecting immunocompromised individuals
Microsporidia spores are small, non-motile, and highly environmentally resistant, penetrating host cells to begin replication
Fungi are eukaryotes closer to animals than plants, primarily aerobic, and act as recyclers in the ecosystem
Pathogenic fungi can switch between multicellular hyphae and single-celled yeasts, with hyphae being septate or coenocytic and forming conidia for spread
Tasks for further study include reading specific sections of Brock Biology of Microorganisms, exploring Candida albicans as a nosocomial pathogen, and understanding its growth, size, cell shape, and treatment options

Lichen Vegetative Structure and Symbiotic Relationships

Lichens have a stratified thallus consisting of layers such as the photobiont layer, medulla layer, and lower cortex layer.
Foliose and fruticose lichens have a lower cortex layer, while crustose and squamulose lichens are directly attached to the substrate at the medulla layer.
Foliose and fruticose lichens attach to surfaces via rhizines, which secrete extracellular gelatinous materials for attachment.
Crustose lichens are flatter and closely attached to surfaces, while squamulose lichens have leaf-like areolated thallus structures.
Fruticose lichens have a shrub or hair-like structure and can resemble plants, with finer, beard-like structures and high surface area for gas diffusion and photosynthesis.
Lichenized fungi, the mycobiont, are heterotrophic, requiring organic carbon as a carbon source and acquiring carbon from living algae or cyanobacterial cells.
Lichenized fungi form housing structures that provide adequate lighting and gas exchange for the photobiont, with only about 25% of lichens forming 3D structures such as foliose or fruticose.
Photobionts are photoautotrophic, requiring light, water, and carbon dioxide for photosynthesis, and release organic carbon, CO2, and minerals leached from the substrate.
Lichens act as carbon sinks, with 50% of CO2 assimilated during photosynthesis used for respiration and the remaining utilized for thallus cell walls and other compounds.
Lichens form tripartite symbioses with green algae and cyanobacterial photobionts, with the cyanobacterial partner responsible for nitrogen fixation.
Lichens serve as bioindicators of air pollution, with fieldwork involving the comparison of lichen biodiversity between car parks and green areas to identify patterns.
Fieldwork on campus involves photographing all lichens in designated areas, returning to the lecture room for identification, and determining observable patterns in lichen biodiversity.

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