DOMAIN EUKARYA KINGDOM PROTISTA II

Multicellular Protista (Red, Brown, & Green algae)  Major primary producers in aquatic systems  Provide home for microorganisms and fishes  The red and brown algae are primary multicellular and mostly marine organisms  Green algae contain many unicellular and mostly freshwater  Cellulose is found in the cell wall of the three phyla among others  Green algae store carbs as starch in the chloroplasts  Red algae store food as floridean & brown algae as laminarin, outside the chloroplast  Red algae lack flagella

Origins of chloroplast in Algae  Chloroplast of red algae resembles that of Cyanobacteria [Chl(a), carotenoid, phycobilins]  Chloroplasts of green algae, Euglenoids, & plants resemble that of Prochloron [Chl(a), (b), carotenoids]  Chloroplast of brown algae, Chrysophytes, & diatoms have the same origin! All have Chl a, c, & fucoxanthin.

1. Brown Algae: Phylum Phaeophyta  Prefer cold agitated, well aerated water (temperate regions)  Common on rocky shores (intertidal zones)  They have a complex anatomy & morphology**  Cell wall contain cellulose & alginic acid (not in other algae)  Reserve food is Laminarin  Range from small filamentous to large multicellular organisms BA

Examples of brown algae that grow in intertidal (shoreline) zone Rockweed BA Kelp Holdfast Stipe

The giant kelps - Are examples of brown algae that grow in deep clear waters (up to 30m) - Brown & red algae provide food (SE Asia) BA

Kelp, giant seaweed Blade Stipe Holdfast BA

Brown Algae: Ectocarpus Plurilocular Sporangium

2. Green Algae (Phylum Chlorophyta)  Include unicellular, colonial, and multicellular organisms  They are resilient & survive many types of disturbances  Mainly freshwater organisms  Closely related to plants because: Have chlorophylls a, b, & carotenoids Store reserve food as starch in the chloroplast Cell wall contains cellulose

Class Chlorophyceae  The only living organisms in which cell division involves a phycoplast (Cleavage furrow)phycoplast  Zygotic meiosis  Mostly freshwater organisms  Produce red, orange, & green snow  Have flagellated and nonflagellated forms GA

Chlorophyceae Phycoplast It insures that cleavage furrow passes between the daughter cells Cell plateCleavage furrow

Motile Unicellular Chlorophyceae  Chlamydomonas: Unicellular  Move by means of two flagella**  Asexual reproduction: haploid cells divide by mitosis producing up to 16 cells  Sexual reproduction** GA

Chlamedomonas

Motile Unicellular Chlorophyceae GA  Sexual reproduction induced by nitrogen starvation

Motile Colonial Chlorophyceae - A colony is an aggregate of independent cells - Daughter colonies detach & form new colonies - Cells’ flagella beat in a coordinate fashion GA

Motile Colonial Chlorophyceae s%20table%20of%20web%20links.htm

Nonmotile Unicellular Chlorophyceae  Example: Chlorella: Lacks flagella, eyespots, and contractile vacuoles  Live in fresh, salt water, and in soil  Reproduce only asexually (mitosis) GA algae.tcoalternativefuels.com/about-algae

Nonmotile Unicellular Chlorophyceae Chlorococcum oleofaciens Filled with asexual spores

Nonmotile colonial Chlorophyceae:  Example Hydrodictyon (water net)  in ponds, lakes, and streams GA

Filamentous Chlorophyceae:  Example Oedogonium**  Filamentous green algae are more complex  Each cell has a specific function  Cells are connected by plasmodesmata like plants  Sexual reproduction is oogamous, meiosis is zygotic GA

O. gracilius OOgonium

Class Ulvophyceae:  Examples: Cladophora and Ulva**  Marine organisms  The only green algae with sporic meiosis  Unlike other green algae, they rarely form dormant zygospores GA

Ulvophyceae: Chladophora

Ulvophyceae Sea lettuce ( Ulva ) The thallus is two cells thick and up to a meter long GA

Class Charophyceae  Unicellular, filamentous, and parenchymatous genera  Zygotic meiosis  a. Spirogyra: (freshwater habitats) GA

 No flagellated stage in its life cycle  Asexual reproduction by fragmentation  Sexual reproduction via conjugation  This forms a zygote which undergo meiosis Conjugation Union of two cells during which genetic material is exchanged GA

Plants evolved from an extinct member of Charophycease (Coleochaetales & Charales)!  b. Chara (stoneworts) resembles ancestor of land plants!  Like plants they have apical growth (differentiated into nodal & internodal regions)  Produce antheridia & archegonia  Sperms are flagellated  Similar cytokinesis GA

Cytokinesis in Charophyceae C. In simple Charophytes: Cytokinesis occurs by furrowing D. In advanced Charophytes: like plants (cell plate & plant- like phragmoplast. Spindles not persistent Phragmoplast found in all green algae except chlorophyceae

3. Red Algae: Phylum Rhodophyta  Marine organisms, common to tropical & warm water  Differ from other algae and plants in that: Contain phycobilin pigments (red), Chloroplasts do not form grana stacks Food reserves is floridean outside the chloroplast Cell wall contain cellulose (galactans), calcium carbonate, lack plasmodesmata  Almost all red algae are multicellular  Have no flagellated forms  The source of agar (mucilage material in cell wall) RA

Red Algae: Bonnemaisonia asparagoides RA

Red Algae: Bonnemaisonia spp RA oides/Bonnemaisonia_asparagoides.htm

Red Algae: Red Algae: Gelidium amansii RA

Red Algae: Red Algae: Amphiroa carolline RA

Can be up to 1 meter long but generally smaller and more delicate than brown algae RAChondrus crispus