Fungi

Kingdom Protista

• ## Domain Eukaryota

  • Definition and Characteristics

    • Eukaryotes are organisms with complex cells that contain a nucleus and other organelles.

  • Organisms included in this Domain:

    • Animals

    • Plants

    • Fungi

    • Protists

    • Bacteria (specifically, eukaryotic bacteria such as cyanobacteria)

    • Archaea

What are Protists?

• Definition:

  • Protista refers to any eukaryote that is not classified as a plant, fungus, or animal.

• Characteristics of Protista:

  • can be unicellular or multicellular, but most are unicellular

  • majority live in aquatic environments

  • nutritional modes include heterotrophic, photosynthetic, and saprotrophic behaviors

  • They are a highly diverse group with no unifying characteristics besides being eukaryotic.

  • Evolutionary importance:

    • Considered the first eukaryotes and ancestors to animals, plants, and fungi

Types of Protists

• Based on energy acquisition:

  1. Plant-like Protists:

     • E.g., phytoplankton, algae

     • Photosynthetic, mostly unicellular

     • Examples:

       • Diatoms (single-celled, silica cell wall)

       • Spirogyra (filamentous algae with spiral chloroplasts)

       • Multi-cellular examples include Red Algae, Brown Algae:

       • Such as Kelp

  2. Fungus-like Protists:

     • E.g., slime molds

     • They can live freely as single cells but usually aggregate to form multicellular reproductive structures

     • Unlike fungi, they utilize intracellular digestion by ingesting rotting material directly.

  3. Animal-like Protists:

     • Unicellular organisms that generally move to obtain energy.

     • Types of movements:

       • Amoebas (via pseudopodia)

       • Flagellates (whip-like projections)

       • Ciliates (coordinated ciliary movement)

Protists and Humans

• Ecological Importance:

  • Foundation of marine and aquatic food chains

  • Significant role in carbon storage helping mitigate climate change\

    • Keep carbon locked out of the atmosphere

  • Some act as decomposers

Kingdom Fungi

Overview of Fungi

• Fungi are also part of the Eukaryote Domain

• Two main categories:

  • Unicellular (yeasts)

  • Multicellular (mushrooms, filamentous structures)

  • Millions of species exist, approximately 100,000 have been classified

• ## Structure and Reproduction in Fungi

• Fungi are unique in their energy acquisition method:

  • They are heterotrophs.

  • Definition: Organisms that gain their energy by consuming organic compounds or other organisms.

  • Fungi conduct external digestion, secreting enzymes that break down food outside their cells before absorption.

• ## Mycelium and Hyphae

• Fungi primarily consist of networks of hyphae which are long filamentous structures that extend throughout their food source (soil, rotting matter, or host)

• Functions of Hyphae:

  • Reproduction

  • Sensory detection

  • Nutrient absorption

  • Association with plant roots, forming mycorrhizal relationships.

• Mycelium: A mass of hyphae; extend for extensive distances, forming the main body of the fungus.

• ## Fungal Lifecycle

• Reproduction can be asexual or sexual, involving spores, and mycelium

• Why is it beneficial to have both reproductive forms?

  • Asexual reproduction allows for rapid population growth in favorable conditions, while sexual reproduction increases genetic diversity.

• ## Diverse Feeding Roles

• Fungi can function as:

  • Decomposers: break down dead organic material

  • Parasites: feed on living organisms without immediately killing them

  • Mutualists: form beneficial relationships with host organisms (e.g., mycorrhizal fungi with plants)

  • Provides soil nutrients to plants while obtaining sugars from photosynthesis

• ## Ecological Importance of Fungi

• Essential for wood decomposition, allowing nutrient cycling within ecosystems

• Mycorrhizal fungi often enhance plant survival and growth, with some plants dependent on their presence

• Culturally and economically important:

  • Source of food (mushrooms), fermentation (yeasts), and antibiotics (e.g., Penicillin)

• ## Detrimental Aspects of Fungi

• Fungi can cause human diseases (e.g., athlete’s foot, yeast infections), crop diseases (e.g., blights), and critical declines in animal populations (e.g., white-nose syndrome in bats).

Additional Notes

• Largest living organism: Honey fungus (Armillaria solidipes) in Oregon, estimated at 2.4 miles across (8,000 years old).

• Experimental considerations in research regarding the effects of mycorrhizal versus non-mycorrhizal plants on offspring survival rates.

  • Independent variable of study designs to consider.