We never eat bread cookies
For cookies have yeast,
And one little bite
Turns a man to a beast
O, can you imagine
A sadder disgrace
Than a man in the gutter
With crumbs on his face?
-- Song of the Salvation Army (trad.)
So, what about all those characteristics mentioned in the last section? The following is a list of the most commonly cited characters shared by most Fungi:
- The Fungi are eukayotes, which may exist in nature as either single and multi-celled organisms, or in both at different points in the the life cycle.
- Fungi are avascular -- no specialized respiratory, digestive or transport systems beyond the hyphae themselves.
- Most fungi grow as tubular filaments called hyphae. A connected mass of hyphae is a mycelium.
- Fungi have a vegetative body called a thallus, composed of hyphae.
- The walls of hyphae are often reinforced with chitin, a polymer of N-acetylglucosamine.
- Fungal cell membranes contain ergosterol, rather than cholesterol.
- The Fungi have a unique biosynthetic pathway for lysine.
- Fungi produce a unique form of tubulin in connection with nuclear division.
- Fungi have small nuclei with very little repetitive DNA
- Mitosis occcurs without dissolution of the nuclear membrane.
- Fungi are never autotrophs. No fungus has chlorophyll or chloroplasts.
- Fungi are usually found either as opportunistic saprophytes (living on dead organic matter) or in some parasitic or symbiotic relationship with plants or other autotroph.
- Fungi digest food outside their bodies: they release enzymes into the surrounding environment (exoenzymes), breaking down organic matter into a form the fungus can absorb
- food reserves stores as glycogen (like animals), not starch (like plants).
- Fungi reproduce by means of spores, budding, or fragmentation.
- Spores may be either sexual or aesexual.
- Spores may be used as a dormant, resting phase, like bacterial spores
In short, Fungi are a rather odd, and distinctly different, part of the tree of life.