Einführung in die Pilze: 1 Flashcards
size of fungi
They are often invisible, and the single hyphae might be small (2
10 µm diameter), but Fungi represent the third biggest global biomass component (after plants and bacteria )
Characteristics of fungi
(1) eukaryotic
(2) typically haploid genome
(3) typically grow as hyphae with apical growth; sometimes as yeast
(4) heterotrophic
(5) osmotrophic nutrient uptake
(6) cell wall primarily composed of chitin and glucans
(7) production of spores
Phylogeny
groups:
1. slime molds
2. Oomycetes
3. true fungi
haploidity
- sexual or asexual propagation
- sometimes morphologically very different
- sexua stages unknown for a vast number of fungi
results of mitotic division
identical to parent= clones
results of karyogamy & meiosis
non- identical to each parent through recombination
yeast-like vs filamentous fungi
- dimorphism
- “yeast” just describes the morphology, not the phylogeny
growth patterns of fungi
-apical growth
driving forces:
1)”birth of new material and autolysis of old material
2) actin cytoskeleton
- branching
- anastomosis (fusion)
The sum of the above leads to the mycelium formation
What are hyphae
Hyphae are essentially tubes of indeterminate length
(but constant diameter) with a rigid wall, containing a
moving slug of protoplasm
heterotrophic
Fungi, like humans , need organically bound carbon as energy source and construction material“ -> they are chemoorganotrophs
osmotrophy
see sl. 22
cell envelope characteristics
- plasma membrane
- periplasmic space
- cell wall
- (capsules, fimbriae..)
cell wall characteristics
- fibrillar polymers
- embedded in matrix
- very dynamic
functions of fungal cell wall & envelope
- osmotic protection
- UV protection (pigments)
- molecular sieve
- interaction with environment
- binding sites for enzymes (proteases, glycosidases etc.)
cell wall organisation
see sl 25
major fibrillar polymers in ascomycetes and basidiomycetes & details
- chitin
- β(1,3)-, β(1,6)-glucan
- glucan & chitin are produced at the plasma membrane (glucan synthase & chitin synthase)
- glycoproteins are delivered in vesicles
structural representation of polymers
see sl 27, 28
The „steady state “ model of hyphal tip growth
•viscoelastic properties of the wall
•new material flows outwards and backwards as more new
components are added
•progressive cross linking causes reduced flow
-cell wall formation is intimately bound to apical growth
what particular substances can the cell wall have?
the cell wall can have important additional pigments, proteins or polysaccharides to
provide functionalities.
Examples:
->Pigments – e.g. melanin (UV-protectant; structural
strength, resistance to stresses,…)
->polysaccharides – e.g. pullulan (food additive for
film formation such as in breath fresheners)
->proteins – e.g. hydrophobins (aerial structures)
fungal reproduction/spores
-Fungi have the ability to produce an enormous number of spores => abilities of fungi to produce great amounts of protein
& biomass in short time => useful for biotechnology
-spore production is also an important hallmark in the distinction of fungal phyla
Ascomycota
-endogenous
spore formation in asci
•mating types:
-bipolar: usually a/A
(or α/a)
Basidiomycota
-exogenous spore
formation from specialized hyphae:
basidia
•mating types -bipolar or tetrapolar and multiallelic (=complicated but increasing chance of mating >>50%)
7 major groups within “true” fungi
-opisthosporidia
-blastocladomycota
-chytridiomyceta
-zoopragomycota
-mucoromycota
-dikaryomycota
>ascomycotina
>basidiomycotina
