plantae...plantae- rhodophyta, chlorophyta, seagrasses 6. amoebozoans- slimemolds 7. fungi-...
TRANSCRIPT
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Division: Chlorophyta(green algae)
I. General CharacteristicsII. MorphologyIII. Distinguishing ClassesIV. Classes in Detail
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~ 16,000 species~ 90% freshwater
Hierarchical system of classification:
Level: suffix: example:Domain EukaryoteGroup PlantaeDivision -phyta ChlorophytaClass -phyceae Ulvophyceae
II. Algal taxonomy
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p y p yOrder -ales UlvalesFamily -aceae UlvaceaeGenus Ulvaspecies fenestrata
DOMAIN1.Bacteria- cyanobacteria (blue green algae)2.Archae3.Eukaryotes
Groups (Kingdom)
1. Alveolates- dinoflagellates
2. Stramenopiles- diatoms, heterokonyophyta
3. Rhizaria- unicellular amoeboids
4 Excavates- unicellular flagellates
“Algae”
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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
Glaucophytes
Rhodophyta
Chlorophytes
Plantae
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Adapted from Sadava 2014
Charophytes
Land Plants
Chl b,starch
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Chlorophyceae
Trebouxiophyceae
Ulvophyceae
Phylogenetics of Chlorophyta (morphological, molecular data)
4 classes:
Chlorophyta
Chl b,starch
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Prasinophyceae
CharophytesCharophyceae
Land plants
a
Encasement of egg
Embryo, cuticle
I. General Green Characteristics:
1) Pigments: ?
2) Chloroplast structure?:
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3) Storage product?
4) Flagella?
Chlorophyceae = freshwater
Trebouxiophyceae = freshwater, soil and marine
Ulvophyceae = marine macroalgae
Classes:
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p y g
Prasinophyceae = primarily marine flagellates, some freshwater; modern representatives of earliest green algae
Charophyceae = freshwater; all terrestrial plants are derived from Charophycean class
II. MorphologyChlorophyta:easiest division to identify visually
• usually bright, grass-green color
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II. MorphologyChlorophyta:easiest division to identify visually
• usually bright, grass-green color
Except -
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Snow algae DunaliellaTrentepohlia parasitic on Monterey Cypress
photo: Morgan Bond
Charophyceans
For classes:- any easy “rules” using external thallus morphology?
- Prasinophyceans are all unicells, but…
10Chlorophyceae Ulvophyceae Ulvophyceae
“napkin ring-shaped parietal”
Diversity in chloroplast shape: (unique to algae)
“cup-shaped parietal”
“axial (plate-like)”
“stellate (star-shaped)”
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“reticulate (net-like)”
axial (plate like)
“multiple discoid”
“ribbon-like”
1. How flagella are attached/constructed:• basal bodies orientation• microtubule roots
III. Distinguishing among classes based on:
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2. Cell covering:• scales vs. cell wall
3. How cells divide: • aspects of mitosis and cytokinesis
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1. How flagella are attached/constructed:-basal bodies orientation-microtubule roots
Flagella
Basal Bodies
III. Distinguishing among classes based on:
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anterior
swimming direction
Cell
Microtubule roots
Flagella- complex cellular projections used for movement- bundle of nine fused pairs of microtubule doubletssurrounding two central single microtubules "9+2"
Basal bodies- attachment site of the flagella- containing a microtubules 9 triplet configuration forming a hollow cylinder
Flagella
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Cell
Flagella
Basal Bodies
Microtubule roots
opposite parallel clockwise counterclockwise
Basal Bodies: ONE per flagellum, located at base of flagellum, anchoring into cell-pairs of basal bodies may be
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Cell
Flagella
Basal Bodies
Microtubule roots
Microtubule roots: -under the cell membrane at point of
attachment of basal bodies- may be cruciate or broadband Cell
Flagella
Basal Bodies
Microtubule roots
16cruciate broad-band
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2. Cell covering- scales vs. cell wallIII. Distinguishing among classes based on:
Scales are made of complex polysaccharides secreted from golgi Cell wall = usually cellulose
prasinophyceae Chlorophyceae, trebouxiophyceae,Ulvophyceae, charophyceae
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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
III. Distinguishing among classes based on:
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closed Open-during Mt nuclear envelope breaks down
metacentric centrioles
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
III. Distinguishing among classes based on:
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Phragmoplast: double microtubules perpendicularto dividing plane-land plants
Phycoplast: microtubules parallel to dividing plane -rare in algae
furrowing furrowing
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
III. Distinguishing among classes based on:
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furrowing = most algae cell plate formation = a few algae and land plants
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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(sp m) nd n n fl ll t d m t ( )
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(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:
Chlorophyceae
Trebouxiophyceae
Ulvophyceae
5 classes:
V. Classes in detail - Chlorophyte Diversity:
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Prasinophyceae
Charophyceae
Land plants
Class Chlorophyceae:
1. How flagella are attached/constructed:b s l b di s i t ti l k i
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• basal bodies orientation = clockwise• microtubule roots = cruciate
2. Cell covering:• scales vs. cell wall = wall
3. How cells divide: • spindle = closed• microtubule organization = phycoplast• division by = furrowing
Microtubule Roots: cruciateBasal Bodies: clockwise
Chlorophyceae
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Cell
Flagella
Basal Bodies
Microtubule roots
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Class Chlorophyceae:
7000+ spp
mostly freshwater
unicells, colonies, coenocytes, filaments,
haplontic life history- 1N thallus, the zygote is the only diploid stage, with “hypnozygote” = thick walled resting stage
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isogamous, anisogamous, and oogamous species
Genera:
Chlamydomonas, Volvox, Dunaliella
Order: Volvocales Genus: Chlamydomonas
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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
Chlamydomonas life history:
Usually asexual
Mt
fluid conditions
moist but not wet conditions
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“palmelloid stage”
Haplontic- Sexual reproduction in unfavorable conditions
28Hypnozygote= resting stage(1/2) (1/2)
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Genus: Volvox
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• 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
Volvox life history
• Oogamous
• Gonidia = specialized cells that divide to become daughter colonies
• Zoospore = spore with
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• Zoospore = spore with flagella
• Endospore = surrounds zoospore
• Mesospore = initially surrounds endospore + zoospore
Genus: Dunaliella
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• Common in salt ponds: have special ion pumps
• Packed with beta-carotene to protect from UV irradiance
• Commercial value (beta-carotene) = used for food coloring and in pharmaceuticals
Chlorophyceae
Trebouxiophyceae
Ulvophyceae
Chlorophyte Diversity
5 “classes”:
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Prasinophytes
Charophyceae
Land plants
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Class Ulvophyceae:
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1. How flagella are attached/constructed:• basal body orientation = counterclockwise• microtubule roots = cruciate
2. Cell covering:• scales vs. cell wall = wall (scales in some reproductive unicells)
3. How cells actually divide: • spindle = closed• microtubule organization = phragmoplast• division by = furrow
Microtubule Roots: cruciateBasal Bodies: counter- clockwise
Ulvophyceae
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Cell
Flagella
Basal Bodies
Microtubule roots
Class Ulvophyceae:
Mostly marine macroalgae, some freshwater too
Haplontic, diplontic, or alternation of generations
No hypnozygotes
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Class Ulvophyceae:
Mostly marine macroalgae, some freshwater too
Haplontic, diplontic, or alternation of generations
No hypnozygotes
Orders to know:
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Orders to know:
• Ulotrichales/Ulvales
• Trentepohliales
• Cladophorales
• Bryopsidales
• Dasycladales
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Ulvophyceans have diverse morphologies
unbranched filament b h d fil t
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unbranched filament
parenchymatous coenocytic/siphonous
branched filament
Division: Chlorophyta
Class: Trebouxiophyceae ChlorophyceaeUlvophyceae Prasinophytes
Order:Ulvales Bryopsidales
CladophoralesUlotrichales Dasycladales
Trentepohliales
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- Unicells, filaments, blades; uninucleate or multinucleate cells
- Simple, haplontic life histories; all with an attached Codiolum stage formed by zygote; zygote undergoes meiosis, producing flagellated meiospores
Focal genera: Ulothrix
Order Ulotrichales – e.g. Ulothrix
Haplontic with codiolum phase-1N thallus, the zygote is the only diploid stage-Codiolum phase- cell wall is from 2N zygote with 1N spores inside
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syngamy
• Cell wall of zygote (2N) stays intact to
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1Ncodiolum
stage
meiosisoccurs
in zygote
2Nzygote
1N zoospores
1N gametophytes
1N gametes
(2N) stays intact to contain new meiospores (N)
•Codiolum stage –dormant until favorable conditions
Division: Chlorophyta
Class: Trebouxiophyceae ChlorophyceaeUlvophyceae Prasinophytes
Order:Ulvales Bryopsidales
CladophoralesUlotrichalesDasycladales
Trentepohliales
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- Uninucleate cells with a single parietal chloroplast - Parenchymatous thallus; mono- or distromatic, sheets or tubes- All cells can reproduce (holocarpic reproduction)- Isomorphic alternation of generations
Focal genera: Ulva
“sea lettuce”
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Order Ulvales e.g. Ulva
Isomorphic Alternation of Generations: organism having a separate multicellular diploid sporophyte and haploid gametophyte stage, sporophyte & gametophyte are same sizes
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Ulva spp• Distromatic• Often ephemeral in intertidal zone• Fast growing, tasty to herbivores• Green tides!
• Tubular• Euryhaline - tolerates freshwater, often occurs near seeps
Ulva intestinalis =
•Green tides!
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Division: Chlorophyta
Class: Trebouxiophyceae ChlorophyceaeUlvophyceae Prasinophytes
Order:Ulvales Bryopsidales
CladophoralesUlotrichalesDasycladales
Trentepohliales
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- Large, multinucleate cells, connected end to end with cross walls- Chloroplasts reticulate or multiple discoid arrayed in reticulate network- Isomorphic alternation of generations
Focal genera:
Cladophora, Chaetomorpha, Anadyomene
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Order Cladophorales e.g. Cladophora
Isomorphic Alternation of Generations: organism having a separate multicellular diploid sporophyte and haploid gametophyte stage, sporophyte & gametophyte are same sizes
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Japanese Cladophora spp: “marimo balls”
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• Size: up to 30 cm (formed by turbulent water + sediments)
• A folktale in which the hearts of a young couple who drown in a lake turn into Cladophora balls
• Meditation – watch balls rising and falling
• Protected species - three day festival to promote conservation
Temporate Cladophorales
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Cladophora Chaetomorpha
- “Pin cushion” alga
- Branched filamentous
- Harbors inverts Nutrients
- Unbranched filaments
- Modified basal cell w/rhizoidalextensions
Tropical Cladophorales
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Ventricaria
- Made up of single central cell (big) and lots of lateral cells (small)
Anadyomene
- Cells become progressively smaller toward periphery
-Small cells fill spaces between large-celled filaments (veins)
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Class:
Order:
Division: Chlorophyta
Trebouxiophyceae ChlorophyceaeUlvophyceae Prasinophytes
Ulvales BryopsidalesCladophoralesUlotrichales
Dasycladales
Trentepohliales
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- Coencocytic/siphonous thallus construction
- Lots of variability in form (uniaxial, multiaxial, etc.)
- Mostly biflagellate anisogamous reproduction; various life histories
- Some calcified: major component of tropical sands remains of coralline greens form a layer >50 m thick at Great Barrier Reef
- Synchronous spawning in tropics
Focal genera:
Order Bryopsidales
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Halimeda CaulerpaCodium “dead man’s fingers”
Coenocytic/siphonous construction:
Multinucleate; no division of cytoplasm with cell walls
Morphology
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cytoplasm with cell walls
“clotting compounds” quickly repair wounds
Uniaxial and multiaxial construction
Morphology
52Bryopsis Codium “dead man’s fingers”
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Codium fragile
Utricles
Morphology
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Gametangium
Utricles: peripheral portions of siphons may be inflated & aggregated to form outer surface gametangia (reproductive structures)
Codium is ~ size of an apple =~30 km of siphons
Kleptoplastids
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(Sacoglossan opistobranchs are thieves!)
- Common in siphonous greens
- Sacoglossan radula adapted to host alga (length of tooth ~ thickness of siphon)
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- Pierce and suck out insides
- Stolen chloroplasts can last up to a month or so
Elysia
Codium fragile
Order Bryopsidales: e.g.Codium
Diplontic: 2N thallus, the gametes are the only haploid stage
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Codium and scallop interaction on East Coast
• Attach and grow on scallops
• Weigh them down and
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Weigh them down and prevent escape from predators
• Cast adrift in heavy storms
• Results in high mortality
Holocarpic reproduction in many tropical members of Bryopsidales
Halimeda
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- Anisogamous, dioecious = separate sexes- Entire thallus turns into gametes- Gametes migrate to surface overnight- Major contributor to tropical sediment
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- Thousands of individuals spawn synchronously
- Water visibility drops to ~ 1m downstream from reef, but disperses within ~1/2 hr
- Empty thallus disintegrates (often within hrs)
- In some species:
gametes positively phototactic
zygotes are negatively phototactic WHY??
- New tissue put on at night (why?)
- New segments not fully calcified, but heavily defended chemically
- Chloroplasts stay in older segments until minutes before sunrise
- Increase in calcification = decrease in chemical defenses
Tropical siphonous greens, timing of growth, and herbivory
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Caulerpa invasion
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• Native in southern Australia• 1st introduced as a non-native in Mediterranean• 2002: introduced at 2 sites in S. California large eradicationattempted
• Grows fast, large, asexual reproduction, and resistant to cold temps• Listed as one of the top 100 invasive species on earth
Caulerpa = uniaxial, but with trabeculae for support
trabeculae = ingrowths of wall material
Morphology
62Siphons form rhizoidal holdfast too
Class:
Order:
Division: Chlorophyta
Trebouxiophyceae ChlorophyceaeUlvophyceae Prasinophytes
Ulvales BryopsidalesCladophoralesUlotrichales
Dasycladales
Trentepohliales
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- Extensive fossil record, group is 500 myo with 11 extant genera - Tropical, shallow water spp- Unicellular thalli with one nucleus and radial symmetry
Celebrity genus: Acetabularia
“mermaid’s wine glass”
1930’s - Hammerling’s experiments with Acetabularia
64mRNA
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Class:
Order:
Division: Chlorophyta
Trebouxiophyceae ChlorophyceaeUlvophyceae Prasinophytes
Ulvales BryopsidalesCladophoralesUlotrichales
Dasycladales
Trentepohliales
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- All terrestrial (~40 spp)- Uninucleate, special urn-shaped gametangia, dispersed by wind?- Branched filaments, numerous discoid plastids, orange due to carotene containing lipid droplets (photoprotective?)- Often epiphytic/parasitic
Focal genus: Trentepohlia
- Often epiphytic/parasitic
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Chlorophyceae
Trebouxiophyceae
Ulvophyceae
5 classes:
V. Classes in detail - Chlorophyte Diversity:
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Prasinophyceae
Charophyceae
Land plants
Class Trebouxiophyceae:
1. How flagella are attached/constructed:b s l b di s i t ti t l k i
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• basal bodies orientation = counterclockwise• microtubule roots = cruciate
2. Cell covering:• scales vs. cell wall = wall
3. How cells actually divide: • spindle = closed; metacentric• microtubule organization = phycoplast • division by = furrow
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Microtubule Roots: cruciateBasal Bodies: counter- clockwise
Trebouxiophyceae
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Cell
Flagella
Basal Bodies
Microtubule roots
Class Trebouxiophyceae:
mostly freshwater and terrestrial algae
unicells, filaments, blades
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Genera: Chlorella, Prasiola
Genus: Chlorella
- Unicellular
- Endosymbiont in freshwater animals
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- Endosymbiont in freshwater animals
- Single, cup-shaped chloroplast
- Used by Melvin Calvin to investigate carbon fixation in plants (Calvin cycle)
- Marketed as a dietary supplement
Genus:Prasiola
- Diplontic- 2N thallus, the gametes are the only haploid stage
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- Found in ultra-high intertidal (spray zone) in areas with highguano
- “Nitrophilic”
- Thalli small (< 2cm), monostromatic blades
- Individuals higher on shore produce asexual (2N) spores
- Individuals lower on shore produce gametes, oogamous
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Prasiola Life History
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Chlorophyceae
Trebouxiophyceae
Ulvophyceae
IV. Classes in detail - Chlorophyte Diversity:
5 classes:
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Prasinophyceae
Charophyceae
Land plants
Class Prasinophyceae:
1. How flagella are attached/constructed:b s l b di s i t ti i bl
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• basal bodies orientation = variable• microtubule roots = variable
2. Cell covering:• scales vs. cell wall = scales
3. How cells actually divide: • spindle = open or closed• microtubule organization = phragmoplast or phycoplast• division by = furrow
Microtubule Roots: cruciateBasal Bodies: opposite
Some Prasinophyceans
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Cell
Flagella
Basal Bodies
Microtubule roots
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Class Prasinophyceae Genus Tetraselmis
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modern representatives of ancestral green (most primitive)
unicellular flagellates
freshwater and marine
one plastid with one pyrenoid
mostly asexual
Chlorophyceae
Trebouxiophyceae
Ulvophyceae
5 classes:
V. Classes in detail - Chlorophyte Diversity:
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Prasinophyceae
Charophyceae
Land plants
Class Charophyceae:
1. How flagella are attached/constructed:b s l b di s i t ti ll l
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• basal bodies orientation = parallel• microtubule roots = broad band
2. Cell covering:• scales vs. cell wall = wall
3. How cells divide: • spindle = open• microtubule organization = phragmoplast• division by = furrow or plate
Microtubule Roots: broadbandBasal Bodies: parallel
Charophyceae
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Cell
Flagella
Basal Bodies
Microtubule roots
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Class Charophyceae:
most closely related to terrestrial plants
usually unicells or filaments, but sometimes colonies and more complex forms
Genera: Desmids, Chara
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freshwater
haplontic- 1N thallus, the zygote is the only diploid stage
oogamous reproduction
dormant zygotes
Algal Life Cycles
Haplontic- 1N thallus, the zygote is the only diploid stage
NMt fuse
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MeN
2Nzygote
1Nspores
grow
Class Charophyceae: Order ZygnematalesDesmids
• 2 semi-cells that are mirror images, nucleus is in center
• asexual reproduction = mitosis
• sexual conjugation = pairing between cells
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between cells
• movement through mucilage secretion
Class Charophyceae: Order Charales Genus Chara
Macroscopic
Freshwater
Can be partially calcified
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Central axis with whorls of branches at nodes
Often smell of garlic
Food and nursery habitat for waterfowl