phylum ochrophyta Flashcards
brown algae, lectures 6 & 7
kingdom plantae
phylum chlorophyta and phylum rhodophyta
kingdom chromista
supergroup stramenopiles
phylum ochrophyta
class phaeophyceae
photosynthetic stramenopiles
biflagellate cells present for most taxa in either vegetative or reproductive cells
heterokonts
unicellular or colonial or multicellular or filamentous
pseudoparenchymatous or parenchymatous
microscopic to the largest of the algae
freshwater and marine
planktonic and benthic
very diverse
believed to be monophyletic having a common ancestor due to origin of organelles
biflagellate cells
2 flagella
heterokonts
different sized flagella
one bearing hairs for sense
one for swimming
parenchymatous
form of cell tissue layers similar to land plants
more complex
supergroup stremenopila
brown algae and similar pigmented relatives (diatoms, golden brown algae, protists
named for distinctive straw-like hairs on one of the two flagella
long flagellum is long and tripartate with hairs
short flagellum is smooth and not tripartate
secondary endosymbiosis
red algal cell becomes the symbiont within another eukaryotic cell
plastids enclosed by FOUR membranes corresponding to algal cell wall and host cell wall
when did brown algae first arise
5000 million years ago
much later than cyanobacteria and green algae
photosynthetic stramenopiles cellular characteristics
standard eukaryotic cells
no multinucleate taxa (cells typically small with one nucleus each)
storage product of chrysolaminarin, laminarin, or leucosin (starches) –> dissolved in vacuoles, cytoplasmic lipid droplets
distinctive plastids and flagella
typical brown algae cell
unusual membrane system around chloroplast (encompasses the nucleus —> chloroplatic endoplasmic reticulum)
pyrenoid large, stalked and surrounded by laminarin starch —> produces and stores storage compounds
chloroplasts have grana- stacks of 3’s, 3 layers of thylakoids
preiplastidal endoplasmic reticulum (PER)
holds plastids
also known as CER
extensions of endoplasmic reticulum that envelop plastids and are sometimes connected to the nuclear envelope
photosynthetic stramenopiles pigments
chlorophyll a as reaction center
chlorophyll c occurs in stroma
B-carotene as yellow accessory
xanthophyll fucoxanthin contributes to yellow-brown coloration
Class Phaeophyceae
300 genera, >1500 species
no unicellular
uniseriate filaments to giant kelps
some are more complex than others
some have plasmodesmata
plasmodesmata
specialized transport cells
similar to sieve elements in flowering plants
transport products from photosynthesis to different parts of the body
generated during cytokinesis, present in cross walls of all brown algal cells
cells retain cell to cell connection
symplastic communication
phaeophyceae importance
symbiotic in marine lichens
some form entire ecosystems that support many species
highest productivity rates (1 kg C m- 2 year)
growth up to 2 ft/day
some species are annuals and others are perennial
life span up to 15 years
large algal biomass
highly successful in cold temperate waters
tissue supported by abundant nutrients in upwelling waters
not in tropical waters for larger taxa
cell wall structure for phaeophyceae
fibers of rigid cellulose within fibrils within cell walls
gels of flexible polysaccharides as alginate —> help retain moisture and not dry out/dessicate
help to be elastic and move while dealing with hydrodynamics
physodes
may be in phaeophyceae
form of inducible herbivore defense
cytoplasmic spheres that contain polychenolic compounds/polymers
produced in epidermal or reproductive cells by Golgi apparatus and ER
migrate through the cytoplasm to cell surface and secrete their contents
when surface is agitated, can initiate this migration
polyphenolics interfere with nerve and muscle function in animals —> can disrupt or damage invertebrate taxa that are feeding
may also act as sunscreens due to high light
growth forms of phaeophyceae
filamentous
aggregates of filaments (pseudoparenchyma)
parenchyma
pseudoparenchyma
tissue made of interwoven filaments
