Part I: Fungal Characteristics
Fungi
Fungi are chemoheterotrophs, meaning:
Chemo-: Their energy comes from chemicals.
Heterotroph: Their carbon comes from organic compounds, like decomposing
organic matter.
Types of Fungi:
Molds: Multicellular
Yeasts: Unicellular
Fungi are crucial in ecosystems because they break down organic matter (e.g., fallen
trees) and recycle carbon (C) and nitrogen (N).
Key Characteristics of Fungi:
1. Aerobic: They require oxygen for growth, though some are facultative anaerobes
(can grow with or without oxygen).
2. Decomposers: They help cycle carbon and nitrogen back into the environment.
3. Cell Wall: Some fungi have cell walls made of chitin, the same material found in
the exoskeletons of insects and crustaceans.
4. High Tolerance: Fungi can grow in high concentrations of sugar, salt, and acid,
which is why they often appear on spoiled food before bacteria do.
Structure of Fungi
1. Hyphae: Filaments that make up the body of the fungus.
oSeptate Hyphae: Hyphae with cross-walls dividing the cells.
oAseptate Hyphae: Hyphae without cross-walls (also called cenocytic
hyphae).
2. Mycelium: The mass of hyphae, often found underground or in the substance the
fungus is growing on (like bread or potatoes).
3. Reproductive Structures:
oAerial Hyphae (Reproductive Hyphae): Hold the spores and are often
visible above the surface.
oVegetative Hyphae: Involved in nutrient absorption but don't produce
spores.
oRhizoidal Hyphae: Hyphae that penetrate into the substrate to obtain
nutrients.
4. Dimorphism: Some fungi can switch between yeast-like and mold-like growth,
depending on environmental factors like temperature.
Reproduction of Fungi
Fungi reproduce both sexually and asexually.
Asexual Reproduction:
oInvolves the formation of spores that are clones of the parent fungus.
oSpores travel to new areas, grow into hyphae, and form a new mycelium.
Sexual Reproduction:
oInvolves genetic recombination between two parent fungi (donor and
recipient).
oThe key terms for understanding sexual reproduction in fungi are:
1. Plasmogamy: The fusion of two haploid cells (one set of
chromosomes from each parent).
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