8 Kingdom Fungi

Kingdom Fungi

Overview

  • Fungi are a separate biological kingdom distinct from plants and animals.

Characteristics

  • Eukaryotic organisms

  • Mostly multicellular (except for yeast, which is unicellular)

  • Reproduce asexually, sexually, or both

Differences Between Fungi and Plants

Fungi

  • Many nuclei per cell

  • Heterotrophic (obtain food by absorption)

  • Lacks roots

  • Chitin present in cell walls

  • No seeds

Plants

  • One nucleus per cell

  • Autotrophic (produce their own food via photosynthesis)

  • Roots present

  • Cellulose in cell walls

  • Produce seeds

  • Note: Fungi are more closely related to animals than to plants.

Fungal Morphology

Basic Structural Units

  1. Hyphae

    • Tightly packed filaments that form the basic structural unit of fungi.

  2. Mycelium

    • A branching network of hyphae, typically found in nutrient-rich environments underground.

  3. Fruiting Body

    • The reproductive structure above ground that produces spores.

Fungal Classification

  • Fungi are classified based on:

    • Structure of their fruiting bodies

    • Methods of obtaining food

    • Methods of reproduction

Fungal Nutrition

  • Extracellular Digestion: Hyphae secrete acids and enzymes to digest nutrients from organic materials before absorption.

  • Absorption occurs within the mycelium, where all hyphae share the same cytoplasm for efficient nutrient movement.

Parasitic Nutrition

  • Fungi absorbing nutrients from living hosts, e.g., using an insect’s body for fruiting body production.

  • Predatory Fungi: Have specialized structures to trap prey, e.g., nematodes in soil.

Mutualistic Nutrition

  • Partnerships with other organisms (protists or plants) that increase the surface area for nutrient absorption.

  • Saprophytic Fungi: Decomposers that feed on dead organisms and organic waste, playing a critical role in nutrient cycling.

Reproductive Methods

Single-celled Fungi

  • Budding: New cells develop as outgrowths of existing cells; common in yeast; primarily asexual reproduction.

Multicellular Fungi

  • Fragmentation: A portion of the mycelium breaks off and starts a new organism.

Sexual Reproduction

  • Spore Formation: Spores are reproductive cells produced in sporangia; can develop into new individuals without fertilization.

  • Spores disperse via air, water currents, or animals and can produce new fungi in favorable conditions.

Importance of Fungi

  • Yeast used in baking and winemaking.

  • Fungi in blue cheese contribute to aroma and taste.

  • Truffles are gourmet edible mushrooms.

  • Penicillin was isolated from mold and is an essential antibiotic.

Downsides of Fungi

  • Can attack crops.

  • Can cause human infections such as ringworm and athlete's foot.

  • Some fungi produce fatal toxins when consumed.

  • Contribute to food spoilage.