Lecture 4: Fungal Growth and Development Flashcards
what is germination?
switching of growth modes
what is isometric growth?
growing equally in all directions and dimensions at the same time
what is polarized growth?
production of apical extensions that increase in a linear dimension (producing filamentous threads)
what are coenocytic/aseptate fungi like?
have no internal cross walls
what may the cross walls of septate fungi have?
pores for communication between cells (microtubules)
what are the 3 features of hyphal tips?
polarized, change direction, show autotropism (grow in a straight line)
what are the 2 types of septa?
complete - imperforate and regulated - perforate
what do perforate septa in ascomycota contain?
Woronin body
what are the septa in basidiomycota called and what do they have?
dolipores with a protective cap called the parenthosome
what drives hyphal extension?
turgor pressure and active mechanical movement toward the tip
what drives the active mechnical movement in hyphae?
Vesicle Supply Centre (VSC) or Spitzenkorper
what is different between the cell cycle in animals/plants and fungi?
in fungi there is not quantitative/spatial relationship between division of nuclei and division of cytoplasm by septation
what 4 responses allow for a steering mechanism?
- thigmotropic (touch)
- chemotrophic (chemicals)
- autotrophic (themselves)
- galvanotrophic (electrical signals)
what 4 ways can hyphae fuse?
- tip-tip
- tip-side
- self/non-self fusion
- specialised (clamp connection)
what is the fusing of hyphae known as?
anastomosing
what occurs as a fungal mycelium forms?
the centre (oldest) dies
what are the 4 phases of fungal growth?
- lag phase
- exponential phase
- linear phase
- deceleration phase
what are limiting factors in fungal growth?
- nutrient limitation
- change in pH
- waste products
- secondary metabolites
what 3 types of tissue can hyphae differentiate into?
generative: bear clamp connections or spores
skeletal: long, unbranched, thin/thick walled
binding: thick walled that branch frequently
what makes polyphores tough and hard?
skeletal and binding hyphae that have no cell contents
what are sclerotia used for?
survival
what are mycelial cords used for?
foraging
what are rhizomorphs used for?
foraging and translocation
how do + and - mating types communicate?
via pheromones using Beta-karotine metabolite
what is mating in ascomycytes known as?
shmoozing
what is the different between homo and heterothallic?
homo: self fertile
hetero: requires partner
what are the 4 types of karyon a basidiomycete can be?
monokaryon: uninucleate haploid
homokaryon: uni/multi- nucleate haploid
dikaryon: binucleate haploid
heterokaryon: multinucleate
what maintains a dikaryon?
clamp cell formation
how are di/heterokaryons established?
somatogamous
what is primary homothallism?
mycelium is sexually self fertile
what is heterothallism?
mycelium requires another mycelium of a different mating type for sexual reproduction
what is bipolar heterothallism?
one mating type gene (with 2 alleles) Aa are compatible but AA and aa are incompatible
what is tetrapolar heterothallism?
2 mating type genes with 2+ alleles but only AB x ab is compatible
what is secondary homothallism?
spores segregate from both mating types making the mycelium self-fertile
