Biology II
Fungi
Introduction of Fungi
• They are classified as eukaryotes (have a
membrane bound nucleus)
• Fungi can be divided into two basic
morphological forms:
– Yeasts
– Hyphae
Yeast
• Unicellular fungi
• Reproduce asexually by blastoconidia
formation (budding) or fission
Hyphae
• Multicellular
• Reproduce asexually and/or sexually
• Most Fungi occur in the hyphae form as
branching, threadlike tubular filaments
– Lack cross walls (coenocytic)
– Have cross walls (septate)
– Clamp connections at the septa which connect the
hyphae elements
Common Characteristics of Fungi
• Heterotrophy-eat other organisms as food
– Three major categories of heterotrophs
• Saprophytes-Feed on dead tissue or organic waste
• Symbionts- mutually beneficial relationship between a
fungus and another organism
• Parasites- feeding on living tissue of a host
– Parasites that cause diseases are called pathogens
– Some parasites are obligate parasites (require a living host)
– Others are facultative or nonobligate (do not require a living
host in order to survive)
Common Characteristics
• Body Form
– Unicellular
– Filamentous-tube-like strands called hypha or
hyphae
– Mycelium- total of hyphae
– Sclerotium=Hardened mass of mycelium that
generally serves as an overwintering stage
– Multicellular-such as mycelial cords, rhizomorphs,
and fruit bodies (mushrooms)
Common Characteristics
• Fungus is often hidden from view
– It grows through its food source, excretes
extracellular digestive enzymes, and absorbs
dissolved food
• Indeterminate growth
Common Characteristics
• Spores- asexual (product of mitosis) or sexual
(product of meiosis) in origin
– Purpose of Spores
• Allows the fungus to move to new food source
• Resistant stage- allows fungus to survive periods od
adversity
• Means of introducing new genetic combinations into a
population
Common Characteristics
• Vegetative phase of fungus is generally
sedentary
• Cell wall present, composed of cellulose
and/or chitin
• Food Storage- generally in the form of lipids
and glycogen
• Eukaryotes-true nucleus and other organelles
present
Common Characteristics
• All fungi require water and oxygen
• Fungi grow in almost every habitat
imaginable, as long as there is some type of
organic mater present and the environment is
not too extreme
• Diverse group, number of describer species is
about 69,000 (estimated 1.5 million species
total)
Phylums of Fungi
• Phylum Zygomycota- common mold found on
land
– Reproduce by zygospores
– Ex: Rhizopus- common bread mold
– Contain root-like structures (rhizoids) to anchor in
bread. Stolons on surface of bread.
Phylum Basidiomycota
• Basidiomycetes- the club fungi, about 22,300
species
• Includes mushrooms, toadstools, puffballs,
shelf fungi, rusts, bird’s nest fungi and smuts
• Characterized by perforate septate hypahe
and the production of basidium (club)
following sexual reproduction.