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Algae and the Origin of Eukaryotic Cells (Brown Algae # (littoral zone…
Algae and the Origin of Eukaryotic Cells
Origin of Eukaryotic Cells
DNA Structure
"naked"
approx. 3,000 genes
contain introns
large segments of DNA do not code for RNA
Nuclear Structure and Division
Prokaryotes: DNA in cytoplasm
nuclei of plants almost identical to animals and fungi
Eukaryotes: DNA in nucleus
Organelles
Prokaryotes: lack membrane-bound organelles
Eukaryotes
nuclei
mitochondria
endomembrane system
dictysomes
endoplasmic reticulum
vacuoles
vesicles
Flagella & Cillia
9+2 arrangement of microtubules
Plastids
Green Algae
Body Construction
Motile Conlonies
all cells are similar; none specialized
Nonmotile colonies
cells have no flagella
Coloy
loosely adhered cells
Filamentous Body
cells held tightly by a lamella
cells divide transversely
Membranous Body
new walls occur in only 2 planes
Parenchymatous Body
cell division occurs in 3 planes
bulky, three dimensional
Coenocytic or Siphonous Body
karyokineis occurs without cytokinesis
giant multinucleate cells result
Life Cycle
#
Monobiontic
involves only one free-living generations
Dibiontic
#
Representative Genera
Unicellular Species
chlorophyll A & B
anterior flagella
plasmogamy
Motile Colonial Species
zygote divides
Filamentous Species
monobiontic life cycle
Laminar Species
cells divide in 2 directions
then cells divide once into a 3rd sheet
Coenocytic Species
Dibiontic Life Cycle
Red Algae
contain phycobilin accessory pigments
often purple, brown, or black
floridean starch
a branched polymer of glucose
Brown Algae
#
Almost all marine
prefer cold water
littoral zone
region between low tide and high tide
laminarin
polymer of glucose, not starch
