Division: Chlorophyta (green algae) II. Algal taxonomy

25 Pages·2014·1.1 MB·English

Division: Chlorophyta
(green algae)
I. General Characteristics
II. Distinguishing Classes
III. Morphology
IV. Classes in Detail

~ 16,000 species
~ 90% freshwater
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II. Algal taxonomy
Hierarchical system of classification:

Level: suffix: example:
Domain Eukaryote
Group Plantae
Division -phyta Chlorophyta
Class -phyceae Ulvophyceae
Order -ales Ulvales
Family -aceae Ulvaceae
Genus Ulva
species fenestrata

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DOMAIN Groups (Kingdom)
1.Bacteria- cyan obacteria (blue green algae)
2.Archae
“Algae”
3.Eukaryotes
1. Alveolates- dinoflagellates

2. Stramenopiles- diatoms, heterokonyophyta

3. Rhizaria- unicellular amoeboids

4. Excavates- unicellular flagellates

5. Plantae- rhodophyta, chlorophyta, seagrasses

6. Amoebozoans- slimemolds

7. Fungi- heterotrophs with extracellular digestion

8. Choanoflagellates- unicellular

9. Animals- multicellular heterotrophs 3

Glaucophytes
Plantae Rhodophyta
Chlorophytes
Chl b, Charophytes
starch
Land Plants

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Adapted from Sadava 2014
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Phylogenetics of Chlorophyta (morphological, molecular data)

5 classes:
Chlorophyceae
C

h
ol
r
Trebouxiophyceae o
p
Chl b, h
y
starch Ulvophyceae t
a

Prasinophyceae

Encasement
of egg Charophytes
Charophyceae

Embryo, cuticle

Land plants
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I. General Green Characteristics:
1) Pigments: ?

2) Chloroplast structure?:

3) Storage product?

4) Flagella?

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3
Classes:
Chlorophyceae = freshwater

Trebouxiophyceae = freshwater, soil and marine

Ulvophyceae = marine macroalgae

Prasinophyceae = primarily marine flagellates, some freshwater;
modern representatives of earliest green algae

Charophyceae = freshwater; all terrestrial plants are derived
from Charophycean class

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II. Distinguishing among classes based on:

1. How flagella are attached/constructed:
• basal bodies orientation
• microtubule roots

2. Cell covering:
• scales vs. cell wall

3. How cells divide:
• aspects of mitosis and cytokinesis

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II. Distinguishing among classes based on:
1. How flagella are attached/constructed:
-basal bodies orientation
-microtubule roots
Flagella
Basal Bodies
Microtubule roots
Cell
anterior
swimming direction 9
Flagella- complex cellular projections used for movement
- bundle of nine fused pairs of microtubule doublets
surrounding two central single microtubules "9+2"

Basal bodies- attachment site of the flagella
- containing a microtubules 9 triplet configuration
forming a hollow cylinder

Flagella
Basal Bodies
Microtubule roots
Cell
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Basal Bodies: ONE per flagellum, located at base of
flagellum, anchoring into cell
-pairs of basal bodies may be
opposite parallel clockwise counterclockwise
Flagella
Basal Bodies
Microtubule roots
Cell
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Flagella
Microtubule roots: Basal Bodies
-under the cell membrane at point of
attachment of basal bodies
Microtubule roots
- may be cruciate or broadband
Cell
cruciate broad-band
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II. Distinguishing among classes based on:
2. Cell covering- scales vs. cell wall
Scales are made of complex
Cell wall = usually cellulose
polysaccharides secreted from golgi
Chlorophyceae, trebouxiophyceae,
prasinophyceae
Ulvophyceae, charophyceae
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II. Distinguishing among classes based on:
3. How cells divide:
(aspects of mitosis and cytokinesis)
• open vs. closed mitotic spindle
• phycoplast vs. phragmoplast
• furrowing vs. cell plate formation in center of cell
closed metacentric centrioles Open
-during Mt nuclear
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envelope breaks down
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II. Distinguishing among classes based on:
3. How cells divide:
(aspects of mitosis and cytokinesis)
• open vs. closed mitotic spindle
• phycoplast vs. phragmoplast
• furrowing vs. cell plate formation in center of cell
furrowing furrowing
Phycoplast: microtubules Phragmoplast: double
parallel to dividing plane microtubules perpendicular
-rare in algae to dividing plane
-land plants
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II. Distinguishing among classes based on:
3. How cells divide:
(aspects of mitosis and cytokinesis)

• open vs. closed mitotic spindle
• phycoplast vs. phragmoplast
• furrowing vs. cell plate formation in center of cell
furrowing = most algae cell plate formation = a
few algae and land plants
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III. Morphology
Chlorophyta:
easiest division to identify visually
• usually bright, grass-green color

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III. Morphology
Chlorophyta:
easiest division to identify visually
• usually bright, grass-green color

Except -
photo: Morgan Bond
Snow algae
Dunaliella
Trentepohlia parasitic
on Monterey Cypress
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For classes:
- any easy “rules” using external thallus morphology?
- Prasinophyceans are all unicells, but…
Charophyceans

Chlorophyceae Ulvophyceae Ulvophyceae
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Diversity in chloroplast shape: (unique to algae)
“napkin ring-shaped parietal”
“cup-shaped parietal”
“stellate (star-shaped)”
“axial (plate-like)”
“ribbon-like”
“reticulate (net-like)”
“multiple discoid”
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