VJ - Fungi Flashcards
What are the common features of fungi? (3)
- No chlorophyl (thus no photosynthesis)
- Heterotrophic – absorb (ready-made) nutrients – secrete enzymes
- Cell walls consist of chitin, not cellulose
What are hypha, mycelium, condiophores and sporangiophores?
Hypha- filaments of cells, septate or aseptate (coenocytic)
Mycelium – mass of hyphae
Conidiophore – on aerial hyphae, bearing conidia (asexual spores)
Sporangiophore – stalk with a sporangium
- holding spores (e.g., in mould)
What are 4 features of a spore?
Spore:
- reproductive structure
- haploid/diploid
- resistant
- often pigmented
Spore types (5)
Chlamydospore – asexual, resting spore, a ‘survival’ structure
- formed via thickening of a hyphal compartment
Conidiospores – asexual, at hyphal tip (conidiophore)
Zygospores – diploid, arising in a zygosporangium
- upon fusion of hyphae, germinate to a sporangium
(bearing haploid spores)
Ascospore – via sexual reproduction, in an ascus (‘sac’)
Basidiospore – via sexual reproduction, on a basidium
What is the asexual life cycle of fungi
Mycelium → Spore-producing structures → Spores → Germination
What is the sexual life cycle of fungi?
Mycelium → Fusion of cytoplasm → Heterokaryotic stage → Fusion of nuclei → Meiosis → Germination
What are features of Zygomycota? (2)
Moulds
Hyphae coenocytic, but septate in reproductive hyphae
Dikaryotic zygosporangia
What are features of Ascomycota? (3)
Sac fungi
- Spore in an ascus
- Septate hyphae
- 8 ascospores in an ascus
(usually, many yeast have 4)
What are features of Basidiomycota? (4)
Club fungi
- Spore on a basidium looks like a club
- Septate hyphae
- 4 basidiospores on a basidium
- Fruiting body offers increased surface area (gills) and elevation to aid spore disperal
What is unique about yeast?
Not a distinct taxonomic group but are either Ascomycota or Basidiomycota
- Most familiar/useful yeast is Saccharomyces cerevisiae (bakers, brewing, wine yeast)
What are 4 features of yeast?
- Are predominantly single-celled
- Grow asexually via budding or fission
- Reproduce sexually either via asco- or basidio-spores
- Form pseudo-hyphae
(i.e., cell chains)
What is yeast taxonomy relied on? (5)
Microscopic, thus taxonomy relied on:
1) Morphology
- Macroscopic vs microscopic (cell)
2) Mode of reproduction:
- budding vs fission
- asco vs basidio
3) Spore number and shape
- (unusual = ejected ballistospores)
4) Physiology:
- growth needs and limit
- fermentarian vs assimilation
5) Genetic makeup
- G:C content, karyotypes, sequences
What are 3 environmental roles of fungi?
Decomposers – break down dead material
Symbionts – mutualistic relationship with other species
Pathogens/parasites – feed off living organisms
How do fungi act as decomposers? (3)
1) Hyphae can penetrate larger items
2) Enzymes are excreted to break down lignin
3) Nutrients are absorbed from decaying material, also made available to other organisms
- i.e., resulting in nutrient recycling
What is mycorrhiza?
Symbiotic association between fungus and roots of a vascular plant
- Fungus benefits: access to carbohydrates
- Plant benefits: access to mineral nutrients
