Aquatic Botany Rhodophytes and Chlorophytes quiz

Explain the process of primary endosymbiosis

• Host feeds on cyanobacteria

• Instead of breaking down the chloroplast, there’s gene transfer (cyanobacteria genome reduced though)

  • Peptidylglycan layer lost

  • Phagosomal membrane lost

• Cyanobacteria’s membranes are retained so it doesn’t die when the host does

• Leads to evolution of chloroplast organelle

What cyanobacterial system is usually retained during primary endosymbiosis?

The electron transport system

What is a proplastid?

• It is what exists before the chloroplast, and eventually becomes a chloroplast after being divided into gametes

What are the different indicators of chloroplast evolution stages?

• Initial: proplastid

• Develops into chloroplast envelope- double membrane in Chlorophyta and Rhodophyta

• Endoplasmic reticulum

  • Some one membrane (Euglenophyta and Dinophyta)

  • Some two membrane (Cryptophyta, Prymnesiophyta, Heterokontophyta)

• Those with two have 4 total??

List an important distinction between cyanobacteria and all other microalgae phytoplankton

• Cyanobacteria lack chloroplasts

• Cyanobacteria do have thylakoids

Describe the stroma

• Matrix inside chloroplast envelope

• Site of CO2 fixation

• Use RuBisCO for the CO2 fixation

True or False: Most photosynthesizers have too much RuBisCO

True, so they store it in the crystalline pyrenoid

Describe thylakoids

• Membranous vesicles or disks

• Contain chlorophyll

• May form bands or be free (phylum specific)

What do lipid droplets do?

They have light-absorbing pigments, which help with light sensing and directionality

How does the thylakoid generate ATP synthesis?

The membrane has a proton gradient which builds as shit moves across it, generating ATP

True or False: Rhotophytes and cyanobacteria have thylakoids that form bands.

False. Their thylakoids are free with phycobilisomes on the surface.

What do phycobilisomes do?

They capture light and transfer it to processing centers

What group has thylakoids that form 2 bands?

Cryptophyta

What groups have thylakoids that form bands of 3 with a girdle?

Euglenophyta and Heterokontophyta

What groups have thylakoids that form bands of 3 without a girdle?

Dinophyta, Prymnesiophyta, and Eustigmatophyceae

What group has thylakoids that form bands of 2-6

Chlorophyta

What are the two main lineages of primary endosymbiosis?

• Red plastids (Rhodophytes)

• Green plastids (Chlorophytes)

Primary endosymbiosis in Rhodophytes results in 2 membranes around the plastids. Where are they thought to come from?

• One is thought to come from cyanobacteria

• The other is thought to come from the food vacuole

• Originated by primary

  endosymbiosis of

  cyanobacteria &

  flagellated heterotroph

Where are phycobilisomes on rhodophytes? How many membranes does the chloroplast envelope have? How many thylakoids?

• On thylakoid bands

• 2 membranes on envelope

• Single thylakoids

How many membranes are in the chloroplast envelope of chlorophytes? How many bands of thylakoids do chlorophytes have?

• 2 membranes in the envelope

• 2-6 bands of thylakoids

How many membranes does the chloroplast envelope have in Cryptophyta? How many bands of thylakoids? How many membranes of chloroplast endoplasmic reticulum?

• 3 membranes in chloroplast envelope

• 2 bands of thylakoids

• 2 membranes of chloroplast endoplasmic reticulum

How many membranes do chloroplast envelopes have for heterokontophyta? What about bands of thylakoids? How many membranes of the endoplasmic reticulum?

• 3 chloroplast membranes

• 3 bands of thylakoids

• 2 membranes of chloroplast endoplasmic reticulum

How many membranes do dinophyta/euglenophyta chloroplast envelopes have? How many bands of thylakoids? How many membranes of chloroplast ER?

• 3 membranes for chloroplast envelope

• 3 bands of thylakoids

• 1 ER membrane

Which arrow is pointing to the pyrenoid?

What is the main function of flagella?

Movement! For sessile organisms, they use flagella to move the surrounding water for things like feeding.

What is an axoneme?

9 doublet microtubules surrounding 2 central microtubules

What comprises 90% of the proteins that make microtubules?

α & β tubulin. Microtubules together form flagella

What is a flagellar collar?

Tunnel through cell wall

Where are radial spokes?

Project from A-microbutules of doublets on perimeter

Describe dynein arms

• Connect outer microtubule doublets A—→B

• ATP hydrolysis causes dynein to move

• A = cargo

• B = track

Describe kinesin

Protein involving the rotation of central microtubules

• Interact with radial spokes causes sliding between adjacent outer microtubules

True or false: most algae have tubular flagellar hairs, while Heterokonts have non-tubular.

False. The opposite is true.

Describe rhodophyta

• No flagella

• One of oldest groups of eukaryotic algae

• Acidic tolerance

• Floridean starch food reserve (variation of land plant starch)

• Cell wall: cellulose in agar and carragenean

What pigments do Rhodophyte chloroplasts have?

• Chlorophylls a & c

• Phycobilisomes

  • Phycocyanin

  • Allophycocyanin

  • Phycoerythricin

• Chromatic adaptation

Describe group Cyanidales within Rhodophyta

• UNICELLULAR

• EVOLVED IN VOLCANIC AREAS

  • Acid hot springs- pH 0.5 ‒ 3

• SMALLEST EUKARYOTIC GENOME

• TEMPERATURES TO 56°C

• BELIEVED TO BE MOST PRIMITIVE OF RED ALGAE

Describe group prophyridiales within rhodophyta

• UNICELLULAR OR CELLS EMBEDDED IN MUCILAGE FILAMENT

• Found in soil

• Phototactic

• Glides over surface with

release of muscilage

• Releases polysaccharides

depending on environmental conditions

Describe the group bactrachospermales within rhodophyta.

• Freshwater alga

• GELATINOUS FILAMENTS

  • Whorled branches around cells

Describe rhotophyta reproduction

• SPERMATIA = Male gametes

  • Released into water

• CARPAGONIA = Female gametes

• CARPOSPOROPHYTE

  • Formed from fertilized carpagonium

  • Produces spores from

    gonimoblast filament

• TETRASPOROPHYTE

  • Formed from spores released by carposporophyte

  • Produces haploid spores that form gametophyte

True or False: Chlorophyte plastids are surrounded by 2 membranes with 3-5 bands of thylakoids.

True, they are.

True or False: Rhodopsin is the photoreceptor for phototactic response in chlorophytes.

True, chlorophytes use chlamydomonas sensory rhodopsin A in high intensity/longer wavelength light, and B in low intensity/shorter wavelength light.

In chlorophytes, the phototactic response to changes in light intensity involves which of the following processes?

A. A change in membrane potential

B. A change in Ca²⁺ levels

C. A change in the beating of the flagella

D. All of the above

D. All of the above

Which of the following chlorophyte genus in order Volvocales are motile in flooded habitats but nonmotile in soil?

A. Chlamydomonas

B. Ulvophyceae

C. Volvox

D. Dunaliella

A. Chlamydomonas

True or False: The prasinophyte Tetraselmis forms symbiotic associations with segmented worm hosts in the group Annelida.

False, they have symbioses with the flatworm Convoluta roscoffrensis.

True or False: Eukaryotic algae originate via endosymbiosis.

True. A flagellated heterotroph engulfed a cyanobacteria, which evolved eukaryotic algae.

Know chlorophyte cell structure and where the following features are located:

• Cell wall

• Chloroplast

• Eyespot

• Pyrenoid

• Starch

• Nucleus

• Golgi bodies

• Mitochondrion

• Flagella

• Colony wall

Describe the scales of cyanobacteria

• Acidic polysaccharides

  • Prasinophyceae

• Theca

  • Glycoproteins & polysaccharides

  • Motile cells of Chlorphyceae

Where is starch formation in chlorophytes? What starches form? Why is this significant?

• Often in pyrenoid

• Made of Amylose (glucose joined by a14 links) and Amylopectin (addition of pectin polymer)

• The starches present in chlorophytes show that they are a precursor to land plants

What pigments are used in chlorophyte chloroplasts?

• Chlorophyll a & b

• Carotenoids

  • Lutein (primarily)

  • Accumulate under stress (orangered)

    • Low N

    • High light

    • High salinity

• Accumulates between thylakoids (β-carotene) or in lipid globules outside chloroplast

• Orange ——> red passes up food chain (must supplement diet of farmed salmon)

Describe chlorophyte contractile vacuoles

• Usually 2 (at base of flagella)

• Alternately contract

• Control H20 content of cell

What attachment points for flagella can chlorophytes have? Who has them?

• Lateral position - Charophyceae

• Anterior position - Ulvophyceae and Chlorophyceae

What are the two shapes for flagella/microtubule roots in chlorophyes? Who has them?

• Broad-band with second smaller root - Charophyceae

• Cruciate - Ulvophyceae and Chlorophyceae

What is a rhizoplast?

An attachment point for flagella, or “flagellar root”

What is the difference between positive and negative phototaxis?

Positive is toward the light, negative is away from light.

What is phototaxis?

Locomotive response to direction & intensity of light

What is phototrophobia?

Response to rapid change in light intensity. The organism will swim backward, then in

new direction

True or False: Chlorophyte eyespots are located near the chloroplast at the base of the flagella

True. The eyespot is also called the stigma, and it contains carotenoids that reflect blue and green light

Where is the layer of lipid droplets in the stroma in chlorophytes?

It is between the chloroplast envelope and thylakoids

What wavelength of light do rhodopsin photoreceptors absorb?

Rhodopsin A: 510 nm (high light intensity)

Rhodopsin B: 470 nm (low light intensity)

Describe Prasinophyceae within Chlorophyta

• PRIMARILY MARINE SPECIES, A FEW FRESHWATER SPECIES

• MOST PRIMITIVE GREEN FLAGELLATES

• MORPHOLOGICALLY VERY DIVERSE

• VERY SMALL < 1 ‒ 30 μm

• Reduced genome

• MICROMONAS FROM PACIFIC OCEAN

• 1 ‒ 8 FLAGELLA MAY BE PRESENT\

• SCALES CONTAIN 2-KETO-SUGAR ACIDS (Not found in other algal flagella)

• 1 GREEN OR YELLOW-GREEN CHLOROPLAST WITH 1 PYRENOID GENERALLY PRESENT (Rarely 2 chloroplasts or 2 pyrenoids)

• EYESPOT USUALLY PRESENT (Occasionally 2 eyespots)

What chloroplast pigments do prasinophytes (chlorophyta) have?

 Chl a & chl b

 Prasinoxanthin

(some species)

 Lutein

 Carotenes

 Zeaxanthin

 Violaxanthin

 Neoxanthin

 Uriolide

 Siphonaxanthin

What is unique about Nephroselmis olivacea (prasinophyceae, chlorophyta)

They have 2 unequal flagella

What is unique about tetraselmis (prasinophyceae, chlorophyta)

 4 flagella covered with hairs & scales

 Marine genus

What is unique about pyramimonas (prasinophyceae, chlorophyta)

 Marine & freshwater

 Common in tidepools

 Move to surface at low tide & attach to sand at high tide

How does tetraselmis anatomy change when they become adults?

 Loss of functional pharynx & mouth

 Worms completely rely on symbionts

 Photoautrophic organisms consuming sugars provided by symbiotic algae

Describe chlorophyceae (chlorophyta)

• PREDOMINANTLY FRESHWATER

• NINE ORDERS (Volvocales)

• MOST HAVE THECA (Sheath surrounding alga)

• MOTILE CELLS HAVE RADIAL SYMMETRY

• FLAGELLA- Anterior or Cruciate

• MANY HAVE RHIZOPLAST

• COMMON HAVE EYESPOTS

• MOTILE CELLS HAVE RADIAL SYMMETRY

Describe Chlamydomonnadaceae (Chlorophyta —> Chlorophyceae—> Volvocales)

FORM ZYGOSPORES

 Germination depends on environmental conditions

 Cells overwinter (cold, dark, dry)

 Germinate during long day length

PHOTOPERIOD TIME MEASUREMENT

 Sense duration of day length (or night length)

FOUND IN FRESHWATER, DAMP SOIL (HIGH N), & SNOW

 Red snow ‒ grow on surface in spring/summer

 Resting spores in winter ‒ migrate to surface
SINGLE NUCLEUS

2 FLAGELLA

 Contractile vacuoles at base of flagella

CUP-SHAPED CHLOROPLAST & CENTRAL PYRENOID

 May have anterior eye spot

What adaptations do dunaliella have to salt?

• Ion pumps in plasma membrane expel sodium from protoplasm

• Production of glycerol to balance intracellular concentration with external salinity

Describe volvocaceae (chlorophyta—>chlorophyceae—>volvocales)

COLONIAL

 Cells number in multiples of 2

 Up to 10,000 cells per colony

EYESPOTS MAY SHOW MORPHOLOGICAL

DIFFERENCES BASED ON LOCATION

 Larger eyespots in anterior end

 Genera specific

ASEXUAL & SEXUAL REPRODUCTION

CAN SWIM AT SPEEDS ≤5 m/h

 Rotates as swims

 Orients toward light

Volvox (within volvocaceae) have an extracellular matrix. What is it made of? What zones does it contain?

• The matrix is a gelatinous sheath made of Hydroxyproline-rich glycoproteins

• Zones:

  • Flagellar

  • Boundary

  • Cellular

  • Deep

Volvox undergo asexual and sexual reproduction. How does this work?

• Sexual:

  • Separate male & female colonies

  • Males release sexual inducer (glycoprotein)

  • Occurs in summer

• Asexual

  • Occurs in spring

How do groups within Charophyceae reproduce?

ZYGNEMATALES / ZYGNEMATACEAE

 Sexually reproduce by conjugation

 Spirogyra

CHARALES

 aka: Stoneworts

 Sexually reproduce by oogonia

& antheridia

Describe charophyceae (chlorophyta)

MOTILE CELLS

 Asymmetrical

 Scales often present

2 FLAGELLA INSERTED LATERALLY

 Microtubular structure

(multilayer structure)

 Broad root & second smaller root

 No rhizoplasts

NO EYESPOTS

Describe Zygnematales (Chlorophyta—> Charophyceae)

FRESHWATER FILAMENTOUS ALGA

 Unbranched filaments

 Often twisted or spiral threads

GAMETES NON-FLAGELLATED

ZYGOTE/ZYGOSPORE RESTING STAGE

HAPLOID STAGE MOST OF LIFE CYCLE

SOME PREFER ACID CONDITIONS

 Mougeotia spp

Describe Spirogyra (Chlorophyta—> Charophyceae—>Zygnematales)

RIBBON-SHAPED CHLOROPLAST

PYRENOIDS OCCUR ALONG LENGTH OF

CHLOROPLAST

NUCLEUS AT CENTER OF CELL

ASEXUAL REPRODUCTION

 Fragmentation of filaments

SEXUAL REPRODUCTION

 Zygote secretes 3 layered wall

(resting stage during winter)

PREFERS HIGH LIGHT & COOL TEMPERATURES

• Spriogyra phototaxis:

  • ALIGNS TOWARD BLUE LIGHT

  • GLIDING MOVEMENT ALONG FILAMENTS

  • FILAMENTS FORM PARALLEL BUNDLES, CURVE, FORM LARGER MAT

Describe Charales (Chlorophyta—> Charophyceae)

COMPLEX PLANT BODY

 Differentiated into nodes & internodes

RHIZOIDS ANCHOR PLANTS TO SEDIMENTS

APICAL GROWTH

FRESHWATER (SOME BRACKISH SPECIES)

 Quiet water

 Clear lakes

CALCIFICATION:

 CaCO3 & MgCO3 deposits

 Localized OH‒ efflux along internode

raises CO32‒ levels

 CaCO3 super-saturated & precipitates

 Calcite crystals deposited in bands

on cell wall

Describe Chara (Chlorophyta—> Charophyceae—> Charales)

WHORL OF BRANCHES AT NODES

BRANCHES GROW TO DEFINED LENGTH

INTERNODES

 Single long cell

 Multinucleate

 Cytoplasmic streaming

GROWTH FROM APICAL CELLS

 Transverse division of apical into

2 daughter cells

 Lower cell

 Internode initial

 Becomes internode