Transcript GA - Oswego
DOMAIN EUKARYA
KINGDOM PROTISTA II
Multicellular Protista (Red, Brown,
& Green algae)
Major primary producers in aquatic systems
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
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
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)
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
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
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
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
Almost all red algae are multicellular
Have no flagellated forms
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