FungiFungi

Fungi are eukaryotic heterotrophs Fungi are eukaryotic heterotrophs that digest food externally and that digest food externally and absorb the the digested materials absorb the the digested materials through their body walls. through their body walls.

Most fungi, including molds and Most fungi, including molds and mushrooms, are multicellular and mushrooms, are multicellular and macroscopic. Yeasts, though, are macroscopic. Yeasts, though, are unicellular and microscopic. unicellular and microscopic.

Like plants, fungal cells have walls, Like plants, fungal cells have walls, but these walls are made ofbut these walls are made of chitinchitin, , not cellulose.not cellulose.

Fungi are classified by the way Fungi are classified by the way they produce sexual spores.they produce sexual spores.

HyphaeHyphae are the basic structure of are the basic structure of threadlike filaments that grow from a threadlike filaments that grow from a fungal spore. fungal spore.

Hyphae grow into a Hyphae grow into a myceliummycelium – a – a cottony mass covering and cottony mass covering and distributed within whatever the distributed within whatever the fungus is feeding on.fungus is feeding on.

Inside the hyphae are cross walls Inside the hyphae are cross walls called called septasepta. Within the septa there . Within the septa there can be one to many nuclei depending can be one to many nuclei depending on the species. on the species.

Cytoplasm flows through Cytoplasm flows through porespores in in the septathe septa

This is a cross-section of This is a cross-section of hyphae. It shows septa, pore hyphae. It shows septa, pore and cytoplasm.and cytoplasm.

Fungi are heterotrophs.Fungi are heterotrophs.

Most are Most are saprobessaprobes,, decomposingdecomposing dead organisms. dead organisms.

Some fungi have symbiotic Some fungi have symbiotic relationships with other organisms. relationships with other organisms.

Parasitic fungi absorb nutrients from Parasitic fungi absorb nutrients from their host through specializedtheir host through specialized hyphae called hyphae called haustoriahaustoria..

Lichens are among the most Lichens are among the most fascinating organisms on this planet. fascinating organisms on this planet. Their very structure is unique: Their very structure is unique: a a symbioses of two organisms -- a symbioses of two organisms -- a fungus and algae --fungus and algae -- so complete that so complete that they behave and look like an entirely they behave and look like an entirely new being. A lichen can literally eat new being. A lichen can literally eat stones, survive severe cold, and stones, survive severe cold, and remain dormant for long periods remain dormant for long periods without harmwithout harm. . What type of What type of relationship is this?relationship is this?

MycorrhizaMycorrhiza is another symbiotic is another symbiotic association in which a fungus lives in association in which a fungus lives in close contact with roots of a plant close contact with roots of a plant partner. What type of symbiosis is partner. What type of symbiosis is this?this?

Fungi use Fungi use extra cellular digestionextra cellular digestion – – breaking down their food outside breaking down their food outside the cellthe cell then absorbing the nutrients.then absorbing the nutrients.

Fungi may reproduce sexually or Fungi may reproduce sexually or asexually. asexually.

Most produce spores which grow Most produce spores which grow when they encounter favorable when they encounter favorable conditions.conditions.

BuddingBudding is a form of is a form of asexualasexual reproduction in reproduction in which mitosis takes place and a new organism which mitosis takes place and a new organism grows out and eventually separates from the grows out and eventually separates from the parent cell.parent cell.

A A sporangiumsporangium

is a sac or case is a sac or case

in which spores in which spores

are produced.are produced.

This is a Rhizopus This is a Rhizopus sporangium. sporangium.

The four phyla of fungi are identified The four phyla of fungi are identified by the by the shape and presence of their shape and presence of their sporangiumsporangium..

Phylum Phylum ZygomycotaZygomycota’s common ’s common names are “bread molds” and “pin names are “bread molds” and “pin molds.”molds.”

Why do they carry these names?Why do they carry these names?

                                

           

                               

         

Two views of a Zygomycota’s Two views of a Zygomycota’s sporangium.sporangium.

Phylum Zygomycota has Phylum Zygomycota has stolonsstolons which grow horizontally across the which grow horizontally across the surface of the food source and surface of the food source and produceproduce

RhiziodsRhiziods which grow down to anchor which grow down to anchor the mycelium to the food source. the mycelium to the food source.

This is the site of most extracellular This is the site of most extracellular digestion and absorbtion.digestion and absorbtion.

Phylum Zygomycota is characterized Phylum Zygomycota is characterized by by zygosporeszygospores – thick walled spores – thick walled spores capable of withstanding unfavorable capable of withstanding unfavorable conditions.conditions.

Phylum Phylum AscomycotaAscomycota are commonly are commonly called “sac fungi.”called “sac fungi.”

Phylum Phylum Ascomycota is Ascomycota is characterized bycharacterized by ascosporesascospores – – sexual spores sexual spores produced inside produced inside anan

AscusAscus – – a saclike a saclike structure in structure in which which ascospores are ascospores are produced.produced.

This phylum also This phylum also has has conidiasporesconidiaspores asexual spores asexual spores produced in produced in conidia.conidia.

Phylum Basidiomycota is also the Phylum Basidiomycota is also the “Club Fungi”.“Club Fungi”.

It is characterized by It is characterized by basidia basidia – – club club shaped hyphae thatshaped hyphae that produce produce basidiaspores basidiaspores during sexual during sexual reproduction.reproduction.