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Division: Chlorophyta
(green algae)
~ 16,000 species
~ 90% freshwater
I. General Characteristics
II. Distinguishing Classes
III. Morphology
IV. Classes in Detail
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Hierarchical system of classification:
Level: suffix: example:
Domain Eukaryote
Group Plantae
Division - phyta Chloro phyta
Class - phyceae Ulvo phyceae
Order - ales Ulv ales
Family - aceae Ulv aceae
Genus Ulva species fenestrata
II. Algal taxonomy
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DOMAIN
1.Bacteria- cyanobacteria (blue green algae)
2.Archae
3.Eukaryotes
Groups (Kingdom)
- Alveolates- dinoflagellates
- Stramenopiles- diatoms, heterokonyophyta
- Rhizaria- unicellular amoeboids
- Excavates- unicellular flagellates
- Plantae- rhodophyta, chlorophyta, seagrasses
- Amoebozoans- slimemolds
- Fungi- heterotrophs with extracellular digestion
- Choanoflagellates- unicellular
- Animals- multicellular heterotrophs
“Algae”
4 Adapted from Sadava 2014
Glaucophytes
Rhodophyta
Chlorophytes
Charophytes
Land Plants
Plantae
Chl b, starch
7 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 Classes: 8
1. How flagella are attached/constructed:
- basal bodies orientation
- microtubule roots
2. Cell covering:
3. How cells divide:
- aspects of mitosis and cytokinesis
II. Distinguishing among classes based on:
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- How flagella are attached/constructed:
- basal bodies orientation
- microtubule roots anterior swimming direction Cell Flagella Basal Bodies Microtubule roots
II. Distinguishing among classes based on:
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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
Cell
Flagella Basal Bodies Microtubule roots
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2. Cell covering- scales vs. cell wall
II. Distinguishing among classes based on:
Scales are made of complex polysaccharides secreted from golgi Cell wall = usually cellulose prasinophyceae Chlorophyceae, trebouxiophyceae, Ulvophyceae, charophyceae 14
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
II. Distinguishing among classes based on:
Open
- during Mt nuclear envelope breaks down metacentric centrioles
15 Phragmoplast: double microtubules perpendicular to dividing plane
- land plants Phycoplast: microtubules parallel to dividing plane
- rare in algae
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
II. Distinguishing among classes based on:
furrowing furrowing 16
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
II. Distinguishing among classes based on:
furrowing = most algae cell plate formation = a few algae and land plants
19 Charophyceans Chlorophyceae Ulvophyceae Ulvophyceae
For classes:
- any easy “rules” using external thallus morphology?
- Prasinophyceans are all unicells, but… 20 “napkin ring-shaped parietal” “reticulate (net-like)”
Diversity in chloroplast shape: (unique to algae)
“cup-shaped parietal” “axial (plate-like)” “stellate (star-shaped)” “multiple discoid” “ribbon-like”
21 Some new terms:
Isogamy – sexual fusion between flagellated gametes that
are similar in size and shape
Anisogamy – sexual fusion between flagellated gametes of
distinctly different sizes
Oogamy – sexual fusion between a flagellated gamete
(sperm) and non-flagellated gamete (egg)
Sporophyte : diploid, 2n, multicellular release spores in
alternation of generations
Gametophyte : hapliod, 1n, multicellular release gametes in
alternation of generations
Review: 22 Chlorophyceae Trebouxiophyceae Ulvophyceae Prasinophyceae Charophyceae Land plants
5 classes:
V. Classes in detail - Chlorophyte Diversity:
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Class Charophyceae:
most closely related to
terrestrial plants
usually unicells or filaments, but
sometimes colonies and more
complex forms
freshwater
haplontic- 1N thallus, the zygote is
the only diploid stage
oogamous reproduction
dormant zygotes
Genera: Desmids, Chara 26 Algal Life Cycles Haplontic- 1N thallus, the zygote is the only diploid stage N Me Mt N fuse 2N zygote
1N
spores grow
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Class Charophyceae: Order Zygnematales
Desmids
- 2 semi-cells that are mirror images, nucleus is in center
- asexual reproduction = mitosis
- sexual conjugation = pairing between cells
- movement through mucilage secretion 28
Class Charophyceae: Order Charales Genus Chara
Macroscopic
Freshwater
Can be partially calcified
Central axis with whorls
of branches at nodes
Often smell of garlic
Food and nursery habitat
for waterfowl
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Microtubule Roots: cruciate
Basal Bodies: opposite
Some Prasinophyceans
Cell Flagella Basal Bodies Microtubule roots 32 Class Prasinophyceae Genus Tetraselmis modern representatives of ancestral green (most primitive) unicellular flagellates freshwater and marine one plastid with one pyrenoid mostly asexual
33 Chlorophyceae Trebouxiophyceae Ulvophyceae Prasinophyceae Charophyceae Land plants
5 classes:
V. Classes in detail - Chlorophyte Diversity:
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Class Chlorophyceae:
- How flagella are attached/constructed:
- basal bodies orientation = clockwise
- microtubule roots = cruciate
- Cell covering:
- scales vs. cell wall = wall
- How cells divide:
- spindle = closed
- microtubule organization = phycoplast
- division by = furrowing
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- Cup-shaped chloroplast, orange eyespot
- Scientists sequenced and mapped genome in 2003
- Used as a model to determine how gene expression works
- Use mutations to determine where genes are on chromosomes Order: Volvocales Genus: Chlamydomonas 38 Chlamydomonas life history:
Usually asexual
“palmelloid stage” Mt fluid conditions moist but not wet conditions
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Haplontic- Sexual reproduction in unfavorable conditions
Hypnozygote (1/2) (1/2) = resting stage 40 Genus: Volvox
- Spherical colonies of 500 – 40,000 cells
- Each colony contains a large number of somatic cells and a small number of reproductive cells
- Zygotes are orange
