DOMAIN EUKARYA
KINGDOM PROTISTA II
Multicellular Protista (Red, Brown,
& Green algae)
 Major primary producers in aquatic systems
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Provide home for microorganisms and fishes
The red and brown algae are primary multicellular and mostly
marine organisms
Green algae contain many unicellular and mostly freshwater
Cellulose is found in the cell wall of the three phyla among
others
Green algae store carbs as starch in the chloroplasts
Red algae store food as floridean & brown algae as laminarin,
outside the chloroplast
Red algae lack flagella
Origins of chloroplast in Algae
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Chloroplast of red algae resembles that of
Cyanobacteria [Chl(a), carotenoid, phycobilins]
 Chloroplasts of green algae, Euglenoids, & plants
resemble that of Prochloron [Chl(a), (b),
carotenoids]
 Chloroplast of brown algae, Chrysophytes, &
diatoms have the same origin!
 All have Chl a, c, & fucoxanthin.
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1. Brown Algae: Phylum
Phaeophyta
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Prefer cold agitated, well aerated water (temperate regions)
Common on rocky shores (intertidal zones)
They have a complex anatomy & morphology*
Cell wall contain cellulose & alginic acid (not in other algae)
Reserve food is Laminarin
 Range from small filamentous to large multicellular
organisms
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Examples of brown algae that
grow in intertidal (shoreline)
zone
Stipe
Rockweed
Holdfast
Kelp
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The giant kelps
- Are examples of brown algae that grow in
deep clear waters (up to 30m)
- Brown & red algae provide food (SE Asia)
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Blade
Stipe
Kelp, giant
seaweed
Holdfast
Brown Algae: Ectocarpus
Plurilocular
Sporangium
http://www.dipbot.unict.it/sistematica/Ectoc_pl.html
2. Green Algae (Phylum
Chlorophyta)
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Include unicellular, colonial, and multicellular organisms
 They are resilient & survive many types of disturbances
 Mainly freshwater organisms
 Closely related to plants because:
 Have chlorophylls a, b, & carotenoids
 Store reserve food as starch in the chloroplast
 Cell wall contains cellulose
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Class Chlorophyceae
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The only living organisms in which cell division
involves a phycoplast (Cleavage furrow)
Zygotic meiosis
Mostly freshwater organisms
Produce red, orange, & green snow
Have flagellated and nonflagellated forms
Chlorophyceae Phycoplast
Cleavage
furrow

Cell plate
It insures that cleavage furrow passes between the
daughter cells
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Motile Unicellular
Chlorophyceae
 Chlamydomonas: Unicellular
 Move
by means of two flagella*
 Asexual reproduction: haploid cells divide
by mitosis producing up to 16 cells
 Sexual reproduction*
Chlamedomonas
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Motile Unicellular Chlorophyceae
Sexual reproduction induced by nitrogen starvation
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Motile Colonial Chlorophyceae
- A colony is an
aggregate of
independent cells
- Daughter
colonies detach &
form new
colonies
- Cells’ flagella
beat in a
coordinate
fashion
Motile Colonial Chlorophyceae
http://www.botany.hawaii.edu/Bot480/Volvocale
s%20table%20of%20web%20links.htm
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Nonmotile Unicellular
Chlorophyceae
algae.tcoalternativefuels.com/about-algae
 Example: Chlorella: Lacks flagella, eyespots, and
contractile vacuoles
 Live in fresh, salt water, and in soil
 Reproduce only asexually (mitosis)
Nonmotile Unicellular Chlorophyceae
Chlorococcum oleofaciens
Filled with asexual spores
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Nonmotile colonial
Chlorophyceae:
http://protist.i.hosei.ac.jp/PDB/Images/Chlorophyta/Hydrodictyon/
 Example
Hydrodictyon (water net)
 in ponds, lakes, and streams
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Filamentous Chlorophyceae:
 Example
Oedogonium*
 Filamentous green algae are more complex
 Each cell has a specific function
 Cells are connected by plasmodesmata like
plants
 Sexual reproduction is oogamous, meiosis
is zygotic
O. gracilius
OOgonium
http://vis-pc.plantbio.ohiou.edu/Hocking/photos/Oed.html
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Class Ulvophyceae:
 Examples:
Cladophora and Ulva*
 Marine organisms
 The only green algae with sporic meiosis
 Unlike other green algae, they rarely form
dormant zygospores
Ulvophyceae: Chladophora
http://www.uwinnipeg.ca/~simmons/cladoph.htm
http://www.gettysburg.edu/~rcavalie/bda_i/091.html
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Ulvophyceae
Sea lettuce (Ulva)
The thallus is two
cells thick and up to a
meter long
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Class Charophyceae
 Unicellular,
filamentous, and parenchymatous
genera
 Zygotic meiosis
 a. Spirogyra: (freshwater habitats)
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Conjugation
Union of two cells
during which
genetic material is
exchanged
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No flagellated stage in its life cycle
 Asexual reproduction by fragmentation
 Sexual reproduction via conjugation
 This forms a zygote which undergo meiosis
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Plants evolved from an extinct member of
Charophycease (Coleochaetales & Charales)!
b. Chara (stoneworts) resembles
ancestor of land plants!
Like plants they have apical
growth (differentiated into nodal &
internodal regions)
Produce antheridia & archegonia
Sperms are flagellated
Similar cytokinesis
http://www.aquaweed.com/chara.htm
Cytokinesis in Charophyceae
Phragmoplast
found in all
green algae
except
chlorophyceae
C. In simple Charophytes: Cytokinesis occurs by furrowing
D. In advanced Charophytes: like plants (cell plate & plantlike phragmoplast. Spindles not persistent
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3. Red Algae: Phylum
Rhodophyta
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Marine organisms, common to tropical & warm water
 Differ from other algae and plants in that:
 Contain phycobilin pigments (red), Chloroplasts do not
form grana stacks
 Food reserves is floridean outside the chloroplast
 Cell wall contain cellulose (galactans), calcium carbonate,
lack plasmodesmata
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Almost all red algae are multicellular
 Have no flagellated forms
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The source of agar (mucilage material in cell wall)
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Red Algae: Bonnemaisonia asparagoides
http://www.horta.uac.pt/species/Algae/Bonnemaisonia_asparagoides/Bonnemaisonia_asparagoides.htm
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Red Algae: Bonnemaisonia spp
http://www.horta.uac.pt/species/Algae/Bonnemaisonia_asparag
oides/Bonnemaisonia_asparagoides.htm
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Red Algae: Gelidium amansii
http://www.botany.uwc.ac.za/presents/Seashore2/75.htm
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Red Algae: Amphiroa carolline
http://www.globaldialog.com/~jrice/algae_page/bush_coralline.htm
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Can be up to 1 meter
long but generally
smaller and more
delicate than brown
algae
Chondrus crispus