week 6 - fungi Flashcards
fungi key features:
fungal cell
- Typical eukaryotic cell structure
- Except:
o Ergosterol instead of cholesterol in plasma membrane (also in some protists)
fungi key features:
flagellated?
- Very rarely flagellated
o So often not motile
fungi key features:
cell wall
o Chitin
o Long chain polymer of N-acetylglucosamine
o Produced by chitin synthase (usually multiple paralogues in a genome)
characteristics of the fungal kingdom
- A monophyletic group
- One common ancestor
- 100,000 species known, total probably >1.5 million
o Likely millions of species we are unaware of
characteristics of the fungal kingdom:
chemoogranotrophs
o All derive energy by the breakdown of organic materia
o Same as us (not like plants)
o Do most of the digestion on the outside
Secrete enzyme
Then stuff wanted seeps through pores
characteristics of the fungal kingdom:
important as..
o Decomposers
Have liganases (breaks down ligan in plants)
Symbiosis – plant life into land (nutrients in soils), interaction and collaboration
o Food and drink industry
o Disease agents (esp. crops)
fungal lifestyles
- Always yeast (Saccharomyces cerevisiae)
- Always hyphal (Agaricus bispora)
o Type of growth: Hyphal tip growth is characterized by the initial establishment of one growth site, which is followed by its continuous maintenance.
o A hypha is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium - A mixture (Candida albicans) = dimorphic
- Reproduction is often asexual
o Hyphal spread
o Single cell budding – e.g. yeast
o Asexual spores
filamentous fungi
- Filamentous Fungal morphologies
o Moulds
o Mushrooms - Fruiting body for spore production
o When conditions are right
filamentous fungi
- growth
- Spore to hyphae = GERMINATION
- GERM TUBE = first hyphae to emerge from a spore
- Some spores have a predefined point for germination = GERM PORE
o Where cell wall is weaker (on purpose) - Some swell before germ tube emerges
- Environmental stimuli needed to initiate
o In favourable conditions spores germinate (humidity, temp, etc)
o Get swelling
o Then one single new hyphae
o Which keeps growing to make a mass of hyphae
o Spores are a vehicle for transmission into new environments
filamentous fungi
consists of:
- Consist of long filaments of cells joint end to end = hyphae
filamentous fungi:
main structure:
Hyphae – rigid tubes containing cytoplasm
o Interconnected compartments, not individual cells
o Interconnected by septum
Extension of cell wall to add structure of hyphae
filamentous fungi:
growth
Filamentous fungi – growth
- Hyphae typically grow by apical growth:
o Extension at the tip
o New cells made at the front
o This is how it grows
New cells being formed at tip
In order to extent
Clustered area at tip of hyphae
Macrovesicles (glucan) with micro vesicles (chitin) inside
tropisms
- Hyphal tips show tropism to a variety of substances
o Nutrients
o Amino acids
o Volatile metabolites
o Sex pheromones
o light
Filamentous fungi
– four types of fungal hyphae
- Septate or Coenocytic
- Vegetative or Arial
Filamentous fungi
separate hyphae
- Joint cells have distinct separations called septa, contain pores
o more typical model
Filamentous fungi
coenocytic hyphae:
- Hyphae consists of fused cells, multinucleated
o More prominent in the older groups of fungi
o No distinct markers between cells
o (any negative mutations in one nuclei very easily compensated more, lots of nucelli as no proper separation)
Filamentous Fungi
– Septa
functions
o Structural support
o Allow movement of cell content between cells
Whole organells (depends on species)
o Damage protection
- Made of similar things as the cell wall
- Structure and control varies between fungal species
