lectures 16-18 Flashcards
2 types of fungi growth
isometric
polarised
hyphae microtubules
connect compartments allowing intercellular communication and reallocation of resources
hyphal tips
are polarised
change direction
show autotropism
septa
permit regulated flow of material
permit compartmentalisation of cells and therefore differentiation
fungal cell wall
maintenance of cell shape
stabilisation of internal osmotic conditions - wall creates pressure, preventing excess water influx
protection against physical stress - physical coat
a scaffold for extracellular proteins and secreted enzymes - polysccharides
what drives hyphal extension/growth
(1) Turgor pressure - closed hydraulic system?
(2) Steady –state or balanced lysis using
the Vesicle Supply Centre (VSC) or Spitzenkörper - organise distribution
rapid movement towards the apex of all the materials needed to create new wall, new membranes and new cytoplasmic component
hyphae can fuse…
tip to tip
for sex: clamp connections
self-fusions
tip to side
to allow the formation of a complex interconnecting network - the fungal mycelium
3 types of differentiated hyphae
skeletal - long, unbranched
generative - bear clamp connections or spores
binding - thick-walled and branch frequently
conidiation
production of asexual spores(conidia)
oldest spore
found at the top, furthest away from the mother spore
what do protists have in common
all eukaryotes
all require water-based environment
all undergo mitosis
most are unicellular
most require oxygen
most are motile
how to protists obtain nutrition
photosynthesis
engulfing prey/phagocytosis
symbiosis
absorption of nutrients
how do protists move
pseudopodia
cilia
flagella
alveolates
contain sacs below their plasma membranes
most are photosynthetic
unicellular
dinoflagellates
mostly marine, photosynthetic endosymbionts, free-living
two flagella
primary producers
apicomplexans
contain an apical complex that facilitates host invasion
all paarasites
complex life cycles and many hosts
ciliates
cilia provide motility and feeding
Complex cellular forms; contractile vacuoles, digestive vacuoles,
Two types of nuclei – distinct role in reproduction
Most are heterotrophic; some contain photosynthetic endosymbionts
stramenopiles
Two flagella of unequal length, with rows of tubular hairs along the larger flagellum
Some have lost flagella
Some are photosynthetic
diatoms
Unicellular but may associate in filaments
Carotenoids give golden or brown colour
Only male gametes possess flagella
Two-piece silica (silicon dioxide) cell walls
Bilateral or radial symmetry
Synthesise Aquatic, phytoplankton “blooms
oomycota
Water moulds (NOT fungi)
Saprobes and biotrophs
Important agents of disease in plants and animals
Cellulose cell wall
rhizaria
Long, thin pseudopodia
Unicellular
Aquatic or soil living
cercozoans
aquatic
form shell-like structures
green algal secondary endosymbionts
made from organic materials enforced with calcium carbonate
e.g. fossilised to form white cliffs of dover
causes of coral bleaching
increased or reduced water temperatures
oxygen starvation caused by an increase in zooplankton
increased sedimentation (due to silt runoff)
Bacterial and fungal infections
changes in salinity
herbicides
low tide and UV exposure
elevated sea levels due to global warming
bioluminescence
from dinoflagellates
from scintillons in cortical regions of cells
controlled by circadian clock and only occurs at night
enzyme = dinoflagellate luciferase
