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Home , Charophyceae, Chlorophyceae, Chlorophyta, Division (biology), Green algae, Phragmoplast

Division: (green )

I. General Characteristics II. Distinguishing Classes III. Morphology IV. Classes in Detail

~ 16,000 ~ 90% freshwater 1

II. Algal

Hierarchical system of classification:

Level: suffix: example: Group Plantae Division -phyta Chlorophyta -phyceae -ales -aceae Ulva species fenestrata

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1 DOMAIN Groups () 1.- (blue ) 2.Archae “Algae” 3. 1. -

2. Stramenopiles- , heterokonyophyta

3. - unicellular amoeboids

4. Excavates- unicellular

5. Plantae- rhodophyta, chlorophyta,

6. Amoebozoans- slimemolds

7. Fungi- with extracellular digestion

8. - unicellular

9. - multicellular heterotrophs 3

Glaucophytes Plantae Rhodophyta Chlorophytes

Chl b, Charophytes Land

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Adapted from Sadava 2014

2 Phylogenetics of Chlorophyta (morphological, molecular data)

5 classes:

Chlorophyceae Chlorophyta

Trebouxiophyceae Chl b, starch Ulvophyceae

Prasinophyceae

Encasement of egg Charophytes

Embryo, cuticle

Land plants 5

I. General Green Characteristics:

1) Pigments: ?

2) 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 •

2. Cell covering: • scales vs.

3. How cells divide: • aspects of and

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4 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 "9+2"

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

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5 Basal Bodies: ONE per , located at base of flagellum, anchoring into cell -pairs of basal bodies may be opposite parallel clockwise counterclockwise

Flagella

Basal Bodies

Microtubule roots

Cell

11 5

Microtubule roots: -under the at point of attachment of basal bodies - may be cruciate or broadband

cruciate broad-band 12

6 II. Distinguishing among classes based on: 2. Cell covering- scales vs. cell wall Scales are made of complex Cell wall = usually 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 • vs. • furrowing vs. cell plate formation in center of cell

closed metacentric Open -during Mt nuclear 14 envelope breaks down

7 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 15

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 16

8 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 parasitic on Monterey Cypress 18

9 For classes: - any easy “rules” using external thallus morphology?

- Prasinophyceans are all unicells, but…

Charophyceans

Chlorophyceae Ulvophyceae Ulvophyceae 19

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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10 Some new terms: – 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)

Review:

Sporophyte: diploid, 2n, multicellular release in alternation of generations

Gametophyte: hapliod, 1n, multicellular release gametes in alternation of generations

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V. Classes in detail - Chlorophyte Diversity:

5 classes: Chlorophyceae

Trebouxiophyceae

Ulvophyceae

Prasinophyceae

Charophyceae

Land plants 22

11 Class Charophyceae:

1. How flagella are attached/constructed: • 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 23

Charophyceae Microtubule Roots: broadband Basal Bodies: parallel

Flagella

Basal Bodies

Microtubule roots

Cell

24

12 Class Charophyceae: Genera: Desmids,  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

 dormant zygotes 25

Algal Cycles

Haplontic- 1N thallus, the zygote is the only diploid stage

Mt fuse N

N Me grow 1N 2N spores zygote

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13 Class Charophyceae: Order Desmids

• 2 semi-cells that are mirror images, nucleus is in center

• asexual reproduction = mitosis

• sexual conjugation = pairing between cells

• movement through secretion

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Class Charophyceae: Order Genus Chara

 Macroscopic

 Freshwater

 Can be partially calcified

 Central axis with whorls of branches at nodes

 Often smell of garlic

 Food and nursery for waterfowl

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14 IV. Classes in detail - Chlorophyte Diversity:

5 classes: Chlorophyceae

Trebouxiophyceae

Ulvophyceae

Prasinophyceae

Charophyceae

Land plants 29

Class Prasinophyceae:

1. How flagella are attached/constructed: • 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 30

15 Some Prasinophyceans

Microtubule Roots: cruciate Basal Bodies: opposite

Flagella

Basal Bodies

Microtubule roots

Cell

31

Class Prasinophyceae Genus

modern representatives of ancestral green (most primitive)

unicellular flagellates

 freshwater and marine

 one with one

mostly asexual

32

16 V. Classes in detail - Chlorophyte Diversity:

5 classes: Chlorophyceae

Trebouxiophyceae

Ulvophyceae

Prasinophyceae

Charophyceae

Land plants 33

Class Chlorophyceae:

1. How flagella are attached/constructed: • 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 34

17 Chlorophyceae

Microtubule Roots: cruciate Basal Bodies: clockwise

Flagella

Basal Bodies

Microtubule roots

Cell

35

Class Chlorophyceae:

 7000+ spp

mostly freshwater

unicells, colonies, , filaments,

 haplontic life history- 1N thallus, the zygote is the only diploid stage, with “hypnozygote” = thick walled resting stage

 isogamous, anisogamous, and oogamous species

Genera: , , Dunaliella

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18 Order: Volvocales Genus: Chlamydomonas

• Cup-shaped chloroplast, orange eyespot

• Scientists sequenced and mapped in 2003

• Used as a model to determine how gene expression works

• Use mutations to determine where genes are on chromosomes 37

Chlamydomonas life history: Usually asexual fluid conditions

Mt moist but not wet conditions

“palmelloid stage”

38

19 Haplontic- in unfavorable conditions

(1/2) (1/2) Hypnozygote 39 = resting stage

Genus: Volvox

• Spherical colonies of 500 – 40,000 cells

• Each contains a large number of somatic cells and a small number of reproductive cells

• Zygotes are orange

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20 Volvox life history

• Oogamous

• Gonidia = specialized cells that divide to become daughter colonies

• Zoospore = with flagella

• Endospore = surrounds zoospore

• Mesospore = initially surrounds endospore + zoospore

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Genus: Dunaliella

• 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

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21 V. Classes in detail - Chlorophyte Diversity:

5 classes: Chlorophyceae

Trebouxiophyceae

Ulvophyceae

Prasinophyceae

Charophyceae

Land plants 43

Class Trebouxiophyceae:

1. How flagella are attached/constructed: • 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 44

22 Trebouxiophyceae

Microtubule Roots: cruciate Basal Bodies: counter- clockwise

Flagella

Basal Bodies

Microtubule roots

Cell

45

Class Trebouxiophyceae:

 mostly freshwater and terrestrial algae

 unicells, filaments, blades

Genera: ,

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23 Genus: Chlorella

- Unicellular

- in freshwater animals

- Single, cup-shaped chloroplast

- Used by Melvin Calvin to investigate carbon fixation in plants (Calvin cycle)

- Marketed as a dietary supplement

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Genus: Prasiola

- Diplontic- 2N thallus, the gametes are the only haploid stage

- Found in ultra-high intertidal (spray zone) in areas with high guano - “Nitrophilic”

- Thalli small (< 2cm), monostromatic blades

- Individuals higher on shore produce asexual (2N) spores

- Individuals lower on shore produce gametes, oogamous 48

24 Prasiola Life History

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