Chapter 5.3 Fungi Characteristics and Morphology HARD

Fungal Characteristics

• Fungi lack chlorophyll and cannot photosynthesize, making them heterotrophic (obtain energy from other sources) unlike plants which are autotrophic (produce their own food).
• Fungi have cell walls made of chitin, differentiating them from plant cell walls made of cellulose.
• Fungi are eukaryotic, possessing a nucleus and membrane-bound organelles, unlike prokaryotic bacteria.
• Fungi membranes contain sterols, a characteristic absent in bacteria. Fungal cell walls lack peptidoglycans, which are found in bacteria.

Fungal Morphology and Reproduction

• Fungi can exist as either molds or yeasts.

• Molds: Multicellular and aerobic, typically reproducing by forming airborne spores.

• Yeasts: Unicellular and facultative anaerobes, capable of reproducing both sexually and asexually through budding or transverse division.

• Hyphae: Thread-like filaments that absorb nutrients for the fungus. They can extend and break off to form new hyphae.

• Mycelium: The interwoven mass of hyphae that forms the visible fungal structure.

• Septate hyphae: Have walls (septa) separating individual cells.

• Non-septate hyphae: Lack walls between cells, forming continuous tubes.

Fungal Nutrition

• Saprotrophs: Fungi that decompose dead organic matter.
• Parasites: Fungi that derive nutrients from living hosts, causing harm.
• Symbionts: Fungi that live in mutually beneficial relationships with other organisms.

Fungal Symbiotic Relationships

• Mycorrhizae: Symbiotic relationships between fungi and plant roots, enhancing nutrient uptake for the plant.
• Lichens: Symbiotic associations between fungi and algae or cyanobacteria.

Fungal Classification

• Fungi are classified based on several factors including dimorphism (the ability to exist in different forms depending on conditions).
• Dimorphism: Some fungi can switch between hyphae and yeast forms depending on temperature or location within a host.

Fungal Reproduction

• Asexual reproduction: A common method involving spore formation and subsequent germination to produce offspring genetically identical to the parent. A faster process than sexual reproduction.
• Sexual reproduction: Less common, involving the fusion of nuclei from two different mating strains of the same species.

Fungal Phyla (Examples)

• Chytridiomycota: Primarily aquatic, oldest and simplest fungi, non-septate.
• Glomeromycota: Non-septate, known for their symbiotic relationship with plant roots (endomycorrhizae) in 80% of plants.
• Zygomycota: Non-septate fungi involved in food spoilage and some plant diseases. Reproduce with zygospores (diploid zygotes).
• Ascomycota: Septate fungi, a vast group including many important food sources and plant pathogens. They reproduce with ascospores (within sac-like structures). Asexual reproduction also involves conidiospores.
• Basidiomycota: Septate fungi characterized by visible fruiting bodies (e.g., mushrooms). Their reproductive cycle involves basidiospores.
• Microsporidia: Non-septate, obligate intracellular parasites of animals, characterized by specialized polar tubules enabling fungal entry into host cells.

Fungal Diseases

• Ergotism: A medieval disease caused by fungus-contaminated rye.
• Histoplasmosis: A lung infection caused by Histoplasma capsulatum, often found in soil contaminated with bird or bat droppings.
• Dermatophytosis (Ringworm): Fungal infection of skin, hair, and nails, transmitted by direct contact and fomites (objects).
• Candidiasis (Thrush & Yeast Infections): Caused by Candida albicans, affecting mouth, throat, and the vulva/vagina.
• Coccidioidomycosis (Valley Fever): A respiratory infection caused by fungus in soil, common in desert regions.

Explore the fascinating world of fungi in this quiz that covers their unique characteristics and reproductive methods. Learn how fungi differ from plants and bacteria, and discover the various forms they take, including molds and yeasts. Test your knowledge on fungal morphology and traits!