Introduction to Fungi

Overview

Fungi (pronounced fun-guy or fun-gee) are a distinct group of organisms.
In contrast to prokaryotes (archaea and bacteria), fungi are eukaryotes, meaning they have membranous organelles and a more complex cell structure.
Eukaryotes include fungi, protists, plants, and animals.

Relationship to Other Organisms: More closely related to animals than to plants.
Heterotrophic: Fungi must consume organic material; they cannot photosynthesize.
Decomposers: Secrete enzymes to digest food outside their cells, absorbing nutrients after decomposition.
Cell Structure:
- Have cell walls made of chitin (a structural polysaccharide also found in arthropod exoskeletons).
- Can be unicellular, multicellular, or dimorphic (switch between forms based on conditions).
Reproductive Methods:
- Reproduce by spores, which can be sexual or asexual.

Prefer moist, slightly acidic environments.
Can grow without light and with/without oxygen.
Form mutualistic associations, such as:
- Mycorrhizae with plant roots: convert nitrogen to a usable form for plants.
- Lichens: an association between fungi and algae.

Fungi can be major pathogens, causing diseases in humans and plants.
Common human fungal infections include athlete's foot, ringworm, thrush, and valley fever.
Valley Fever:
- Caused by fungi in soil, prevalent in deserts.
- Symptoms: cough, blood in sputum, weight loss, rash, chest pain, fatigue.
- Non-contagious, requires specific testing for diagnosis.
Opportunistic infections occur in immunocompromised individuals (e.g., cancer, HIV).

Production of antibiotics, such as Penicillin, which has significantly increased human lifespan.
Food production:
- Cheeses (e.g., blue cheese), alcohols (e.g., beer, wine), and bread products use yeast (a type of fungi).
- Soy products like soy sauce, miso, tofu.
Industrial and agricultural uses:
- Produce chemicals (citric acid, malic acid, lactic acid) and enzymes (lipase for detergents).
- Biological control of pests by targeting specific insect species.

Fungi are primary decomposers in forests, capable of breaking down lignin and cellulose in wood.
Essential for nutrient cycling, replenishing soil nutrients like nitrogen, phosphorus, and sulfur.

This concludes the overview of fungi. They play critical roles in ecosystems, human health, and industry.