Fungi

Fungi may be filamentous or non-filamentous

• Filamentous fungi; these form when hyphae (long filaments of cells) combine to form a mycelium.

The mycelium may have cross-walls (made of chitin and ergestol), in which case the fungi has septate hyphae

If it does not have cross-walls it has coenocytic hyphae and may exhibt cytoplasmic streaming; free movement of materials throughout the hypha, due to a lack of cross-wall barriers 

• Non-filamentous fungi grow as colonies

Examples include yeast

• Dimorphism

Some fungi can exist as their filamentous or non-filamentous fungi, in which case they exhibit dimorphism

Dimorphism is usually temperature dependent 

Most fungi reproduce using asexual spores:

• The haploid spore-producing structure produces haploid spores
• Once released, these spores germinate
• Once germinated, the spore form more mycellium

Spore production:

• Mitosis; specialised hyphae produce spores by mitosis
• Budding; uneven cell division may also create spores 
• Hyphal fragmentation; the hyphae may fragment to produce spores

Some fungi may also release sexual spores, which are genetically different from the parent fungi

• Plasmogamy: The cytoplasm of two mycellium fuse to give a structure with two distinct nuclei 
• Karyogamy: The two nuclei fuse to give a structure which is diploid
• This diploid cell undergoes meiosis, producing 4 haploid spores
• These spores germinate once released to become a mycellium

• Some fungi, particularly of the genus ascomycota, form symbionts, mutalistic relationships with other organisms
• Mycorrahizae is a particular symbiont which sees fungi associating with plant roots. Up to 90% of plant roots form these symbiotic relationships
• Ectomycorrahiza occurs when the fungi grows between the root cells
• Arbuscular mycorrhiza occurs when the fungus invades the root cells
• Lichens are a commonly seen symbiont on trees and could be described as an 'air-quality barometer' 
• Lichens are symbiotic relationships between fungi and photosynthetic cells such as algae 

• May have been the first fungi to evolve
• Are motile and have flagella
• Produce sexual and asexual spores 
• Live in soil and water
• Saprotrophs
• Cause disease in amphibians

• Saprotrophs
• Have coenocytic hyphae and so are multi-nucleate 
• Produce sexual and asexual spores 

• Form important symbiotic relationships with lichens 
• Produce sexual and asexual spores
• Saprotrophs

• Form mainly asexual spores 
• Saprotrophs
• Have a large fruiting body (mushrooms)
• Septate hyphae