L20 Flashcards
What are the origins of fungi?
Pre-Cambrian, 760million - 1.06 billion years, more closely related to animals. >100,000 species identified, colonise a range of habitats.
What are the defining characteristics of fungi?
Eukaryotic, they have a membrane bound nuclei, and are membrane bound organelle. They are typically haploid with many several nuclei within each hyphae, many budding yeasts are diploid. Produce spores, sexually and asexually. Varied in size and shape
What are more defining characteristics of fungi?
Heterotrophic they depend on pre-formed organic nutrients, typically grow as hyphae, cell walls of chitin and glucans, absorb soluble nutrients through the cell wall and plasma membrane
What is the growth process in fungi?
Vegetative body is a unicellular or multicellular thallus, unicellular fungi are yeasts. Most are multicellular.
What are the two distinct morphological stages in fungi?
Vegetative and reproductive
What does the vegetative stage consist of in fungi?
Thread-like structures called hyphae. A mass of hyphae is called mycelia. Hyphae have a tubular structure, and those tubes can be divided by cross walls called septa.
What are septa?
Hyphae tubular structure cross walls. Perforations allow nutrients to move from cell to cell along the hypha. Ascomycetes are simple pores with woronin bodies which are membrane bound proteinaceous organelles that can block pores. Basidomycetes are dolipore with parenthesome which allows for cytoplasmic continuity but blocks movement of large organelles
How do fungi eat?
Use complex organic compounds as a source of carbon, do not fix nitrogen from the atmosphere, digestion precedes ingestion. Exoenzymes transported out of the hyphae process nutrients. Glycogen is used for storage.
What special structures does fungi have?
Appressoria which is a penetration structure
Haustoria which are specialised hyphae
Rhizomophs which are mycelia cords
Chlamydospores which are spores within hyphae
Sclerotia which is the asexual, dormant resting body
What are the life habits of fungi?
Parasite/pathogen it causes disease. Symbiont forms associations with other organisms. Saprotroph gains nutrients from non-living materials.
What do the fungal pathogens of plants do ?
They obtain nutrients from the living tissues of their host. This can be host specific e.g. in fusarium oxysporum. They can be biotrophic as they feed without killing. Or necrotrophic being aggressive and killing the host.
What are the fungal pathogens of humans?
There are 200 species that infect humans, infections can be mycosis which is infection and direct damage, mycotoxicosis which is poisoning by contaminated food, or allergies. They can be opportunistic infections, or immuno-compromised or dermatophytic fungi.
What is a fungal pathogen of insects example?
Ophiocordyceps unilateralis, fungus results in alteration of behavioural patterns of the infected ant. Fungus then kills the ant and continues to grow as its hyphae invade more soft tissues.
What are the fungal symbionts of plants?
Mycorrhiza, lichens, endophytes,
What are mycorrhiza?
Associations between fungi and roots, fungi dependent on plants for carbon, plant dependent on fungi for phosphorus. Arbuscukar mycorrhiza - hyphae penetrate the root cell. Ectomycorrhiza - hyphae do not penetrate root cells.
What are lichens?
Photosynthetic partner
What are endophytes?
Do not harm the plant, may activate plant defence genes. Produce anti-feedants.
What is fungal-animal mutualism?
Fungus provides protection and insects provide nutrients
What are fungal saprotrophs?
They feed on dead organic matter, important role in decomposition starch, cellulose, proteins, chitin, keratin, and lignin. Recycle major nutrients, significant spoilage agents, dry rot and sooty moulds. Mycotoxins
Are oomycetes fungi?
No
How many phyla are there within the kingdom fungi?
8
What are the main phyla in the kingdom of fungi called?
Basidiomycota, ascomycota, glomeromycota, zoopagomycota, mucoromycota, blastocladiomycota, chytriduomycota, cryptomycota, microsporidia
What are fungi-like organisms?
Oomycota e.g. potato blight, water mould, downy mildew, root rot. Slime moulds. They are classified as protists
What are some key differences between phyla in fungi?
Basidiomycetes produce asexual spores, ascomycetes produce asexual spores, these are called ascospores and form inside asci. Glomeromycetes forming a fruit body called a sporocarp.
What is the process of asexual reproduction in fungi?
Fungi reproduce asexually by fragmentation, budding or producing spores. Fragments of hyphae can grow new colonies. Somatic cells in yeast form buds. Most common mode of formation is asexual spores - genetically identical to parent.
What are the three steps in sexual reproduction in fungi?
Cell fusion, nuclear fusion, meiosis
What happens in sexual production in fungi?
Cell fusion there is plasmolygamy between two haploid cells, two different haploid nuclei. Nuclear fusion there is karyogamy of the two haploid nuclei, single diploid nucleus. Meiosis there are four haploid cells
What are the advantages of sexual reproduction in fungi?
Introduction of genetic variation, allows for response to adverse environmental conditions. Two mating types are produced. Homothallic where both mating types present or heterothallic where different but compatible mycelia required
What are the reproductive structures in basidiomycetes?
Basidia - sexual
Conidiophores - asexual
In basidiomycetes what do clamp connection do and what are they?
Hook-like structure which ensures each cell/segment of hyphae receives a set of different nuclei.
Is there genetic variation in basidiomycetes?
Yes
What are the two types of reproductive structures in Asomycetes?
Conidiophores- asexual
Gametangia - sexual
What are the male gametangia in ascomycetes?
Spermatium - detached cell
Antheridium - differentiated region
What are the female gametangia in ascomycetes?
Ascogonium - always differentiated region
What is the importance of fungi in human life?
Food, fermentation, pharmaceuticals, washing powder, biocontrol, plant growth
