Summary of Fungi Study

Kingdom Fungi

  • Highly diverse, found in aquatic and terrestrial habitats.
  • Unicellular or multicellular (yeasts and molds).
  • Heterotrophs: absorb nutrients using hydrolytic enzymes.
  • Act as decomposers, parasites, or mutualists; crucial for nutrient recycling.

Structure and Function

  • Unicellular: yeasts in moist environments; multicellular: hyphae (mycelium) for absorption.
  • Hyphae grow rapidly at tips; composed of chitin for strength.

Hyphae Types

  • Septate: divided by septa; Coenocytic: joined multinucleate cells.
  • Adapted for nutrient absorption and trapping prey.

Mycorrhizal Fungi

  • Associations with vascular plants enhance nutrient absorption.
  • Types: Ectomycorrhizal (sheaths around roots) and Arbuscular (penetrate root cell walls).

Life Cycle of Fungi

  • Can reproduce sexually (plasmogamy and karyogamy) or asexually (via spores).
  • Sexual reproduction involves two parent mycelia and genetic diversity through meiosis.

Asexual Reproduction

  • Molds: filamentous fungi producing haploid spores (conidia).
  • Yeasts: reproduce via budding.
  • Deuteromycetes lack sexual reproduction capacity.

Evolution of Fungi

  • Evolved from unicellular flagellated ancestors.
  • Closely related to animals than plants.
  • Oldest terrestrial fungi fossils ~440 million years ago.

Phylogenetics and Classification

  • 145,000 known species; ~2,000 discovered annually.
  • Major fungal phyla: Chytridiomycota, Zygomycota, Mucoromycota, Ascomycota, Basidiomycota.

Functional Roles of Fungi

  1. Decomposers: recycle nutrients, breakdown organic materials.
  2. Parasites: cause plant blight, can be harmful to human health.
  3. Mutualists: cooperate with plants, increase nutrient uptake; aid in plant resilience.

Fungal Mutualisms

  • Leafcutter ants and fungi: symbiotic relationship aiding digestion.
  • Lichens: symbiosis between fungi and photosynthetic organisms, fostering growth.

Practical Uses of Fungi

  • Used in food production (bread, cheese, alcoholic beverages).
  • Source of antibiotics (e.g., penicillin) and medications.
  • Model organisms for genetic research; potential biofuel sources from certain species.