Chlorophytes

What did the original chlorophytes absorb through endosymbiosis?

Cyanobacteria and a flagellated heterotroph

List cell structures in a chlorophyte

• nucleus

• chloroplast

• pyrenoid

• starch

• flagella

• eyespot (at end of chloroplast)

• golgi bodies

• mitochondrion

• cell wall

• colony wall (made of glycoproteins)

Describe the structural components of the chlorophyte cell wall

• cellulose

• xylan or mannan sugars

Describe the scale structure of chlorophytes

• acidic polysaccharides

• theca

How many chloroplast envelopes and thylakoid bands are present in chlorophytes?

• 2 chloroplast membrane envelopes

• 3-5 bands of thylakoids

True or False: Chlorophytes have a chloroplast endoplasmic reticulum

False

Where does starch form in chlorophytes?

often in the pyrenoids

What pigments are present in chlorophytes?

• chlorophyll a and b

• carotenoids

  • primarily Lutein

Describe the contractile vacuoles in chlorophytes

• 2 at the base of flagella

• alternately contract

• control water content of cell

Describe flagella of chlorophytes

• attach either laterally or anteriorally

• have microtubular roots

• rhizoplast at flagellar root

Describe phototaxis vs photophobia

• phototaxis is locomotion towards light

• photophobia is locomotion away from light

What does the rate of flagellar movement depend on?

Ca2+ concentration in the cytoplasm

high intensity light causes photophobic (stop) response

low intensity light causes phototaxis (orientation) response

Describe chlorophyte eyespots

• located near base of flagella

• layer of lipid droplets in stroma

• plasma membrane overlies eyespot

• contains carotenoids

• reflects blue and green light to photoreceptor

Describe rhodopsin in chlorophyte

• located in plasma membrane above eyespot

• contains chromaphore and proteins

• absorbs light at 500 nm

At what wavelengths do rhodopsin a and b absorb light?

• rhodopsin a absorbs at 510 nm and triggers a photophobic response

• rhodopsin b absorbs at 470 nm and triggers a phototaxis response

What are the four classifications of chlorophytes?

• prasinophyceae

• ulvophyceae

• chlorophyceae

• charophyceae

Describe prasinophyceae

• primarily freshwater

• most primitive of green flagellates

• very diverse

• very small

• reduced genome

What pigments are present in prasinophytes

• chl a and chl b

• prasinoxanthin

Describe symbiosis is prasinophytes

• flatworm and green algae symbiosis

• photoautotrophic organisms consume sugars provided by algae

Describe chlorophyceae

• predominantly freshwater

• nine orders

• most have theca

• anterior and cruciate flagella

• most have rhizoplasts

• common to have eyespots

• motile cells have radial symmetry

Describe volvocales

• flagellated and motile vegetative cells

• unicellular and multicellular

• require high N content

Why do chlamydomonas (volvocales) form zygospores?

• cells can overwinter in the absence of favorable conditions

Describe the salt adaptations of dunaliella

• ion pumps in plasma membrane expel sodium from protoplasm

• production of glycerol to balance intracellular concentration with external salinity

Describe volvocaceae colonies

• up to 10,000 cells in multiples of 2

• cells stay on surface of a hollow sphere

Describe volvox extracellular matrix

• gelatinous sheath

• 4 zones: flagellar, boundary, cellular, and deep

True or False: charophyceae are closely related to land plants

True

How do charophyceae reproduce?

Sexually reproduce by conjugation

Describe motor ability of charophyceae

• 2 flagella in microtubular structure