Fungi Summary Notes

Importance of Fungi

  • Role in Ecosystem:
    • Essential for nutrient cycling; speeds up the carbon cycle by breaking down organic matter.
    • Some fungi are partner to plants through mycorrhizal relationships, enhancing plant growth.

Classification of Fungi

  • Estimated 110,000 species described; potentially 6 million total.
  • Growth forms:
    • Yeasts: Single-celled fungi.
    • Mycelia: Multicellular fungi with extensive networks of hyphae.

Fungal Structures

  • Hyphae:
    • Septa: Divides most hyphae into compartments.
    • Coenocytic Hyphae: Multinucleate cells.
  • Reproductive Structures:
    • Various types observed in sexual reproduction (illustrated in figures).
    • Asexual reproduction via conidia (spores).

Decomposition and Nutrition

  • Extracellular Digestion: Fungi digest food outside their body before absorbing it.
  • Breakdown of:
    • Lignin: Using lignin peroxidase enzyme to convert lignin into simpler molecules.
    • Cellulose: Through enzymes called cellulases that convert cellulose into glucose.

Life Cycle of Fungi

  • Involves mitosis and meiosis, alternating between haploid (n) and diploid (2n) stages.
  • Key stages include:
    • Plasmogamy: Fusion of cytoplasm.
    • Karyogamy: Fusion of nuclei.

Key Lineages of Fungi (Selected)

  • Chytrids:
    • Aquatic fungi; can be mutualistic or parasitic.
    • Notable species: Batrachochytrium dendrobatidis.
  • Zygomycetes:
    • Common food molds; reproduce via spores.
    • Example: Rhizopus nigricans (bread mold).
  • Basidiomycota:
    • Includes mushrooms; crucial for decomposing wood.
    • Economic significance; some are edible, others toxic.
  • Ascomycota:
    • Includes yeasts and lichens; vital symbiotic relationships with plants.
    • Ectomycorrhizal fungi assist tree growth.