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algae and the origin of eukaryotic cells (dinoflagellates # (oomycetes…
algae and the origin of eukaryotic cells
concepts
endosybiosis- an organism lived inside another and both benefited
protozoan and algae
embryophytes
origin of eukaryotic cells
dna structure
more complex than prokaryote
nucleosomes, histones, and formation of chromosomes
nuclear structure and division
dna located within the nucleus separated by 2 nuclear membranes
has a true nucleus
organelles
nucei and mitochondria
flagella and cilia
origin of mitochondria and plastids: the endosymbiont theory
autogenous theory
endosymbiont theory- prokaryotic cell has evolved to the point of having eukaryotic features
origin of mitochondria
engulfed organism had the potential to evolve into a mitochondria
origin of plastids
plastids could arise if the engulfed partner were photosynthetic
primary endosymbiosis gave rise to clade containing red and green algae and glaucophytes
secondary endosymbiosis- produced other lines of algae
heterokonts- gave rise to brown algae, golden brown algae, yellow algae, and diatoms
types of cytokinesis
cytokinesis occurs by a phycoplast
characteristics of various groups of algae
green algae
lifecycles of green algae
algae that have no sexual reproduction is the cell cycle
sexual reproduction- meiosis and mitosis
dibiontic- theres an alternation of generation between haploid and diploid
gametophyte and sporophyte may resemble each other and alternation of isomorphic generation occurs
sporophytes produce spores by meiosis
gametes were the following
isogamous- identical
anisogamy- slight differences
oogamy
body construction in green algae
motile colonies
nonmotile colonies- cells lose their flagella
filamentous body- cells held tightly by a middle lamella and if cells divide transversely
membranous body- new walls occur in cell
parenchymatous body
siphonous body
representative genera of green algae
motile colonial species
cells greatly resemble chlamydomonas, produced when zgote divides
filamentous species
members of genus ulothrix are simple types of filamentous green algae
monobiontic lifecycle
zygote germinates via meoisis and produces 4 haplois zoospores
swimming gametes are not formed, instead filaments undergo conjugation
green algae and embryophytes
stretophytes
red algae
constitutes large group of algae
excess photosynthate is stored as floridean starch
walls of algae lack plasmodesmata
contains distinct pit connections
brown algae and their relatives: the heterokonts
brown algae
marine
found on rocky coasts growing in littoral zones
region between low tide and high tide
laminarin- storage product of brown algae
complex brown algae is Fucus
common on rocks
branched bodies called receptacles
small cavities- conceptacles
yellow-green algae
occur mostly in fresh water
many were thought to be green algae until chlorophyll c was discovered
some have an unusual body that consists of long tubular coenocyte
golden brown algae
#
consists of 70 genera and 325 species
living cells float in warm sunny surface waters like diaoms
diatoms
each cell has a wall composed of two halves
easy to recognize
dinoflagellates
#
oomycetes
lacks chloropasts
parasitic or saprophytic
sexually reproduce
no histones but has what appears to be chromosomes
motile and unicellular
contains a flagella
red tide
euglenoids
#
photosynthetic
swim actively with 2 flagella
one short one long
this is an image of green algae
this is an image of the red tide
this is an image of a euglenoid
both are unicellular
euglenoids are eukaryotic
both float in warm sunny surfaces of water
