D Kingdom Protista Part 2

Algae Structure • • • •

Lack tissue differentiation Algae form gametes in single-celled gamete chambers called gametangia Have chlorophyll A pyrenoids: structures associated with algal chloroplasts that synthesize and store starch

1. Unicellular Algae o Consist of single cell o Most free-living aquatic organisms; together known as phytoplankton o Phytoplankton form the base of nearly all marine & fresh water food chains 2. Colonial Algae o Consist of groups of individual cells acting in a coordinated manner o Some cells can become specialized  division of labour 3. Filamentous Algae o Multicellular, slender, rod-shaped, composed of cells joined end to end o some have structures that anchor it to the ocean bottom 4. Multicellular Algae o Usually large & complex and often appear plant-like; known as seaweeds/kelp o Stem-like portion of a seaweed called a thallus Classification Phylum Chlorophyta – Green Algae • Single cells and colonies • Filamentous and multicellular forms • Characteristics shared with plants: o Chlorophyll A & B o Carotenoids: accessory pigments that capture light energy and transfer it to chlorophyll A o Store food as starch o Cell walls made up of cellulose • Most species aquatic • Some symbiotic partners with invertebrates such as corals Phylum Phaeophyta – Brown Algae • Contain chlorophyll A & C • Contain flucoxanthin: accessory pigment that gives brown colour • Store food as laminarin: • laminarin carbohydrate whose glucose units are linked differently than those of starch • mostly marine

Phylum Rhodophyta – Red Algae • Contain chlorophyll A & C • Contain accessory pigments called phycabilias • Phycabilias allow red algae to live at depths uninhabitable by other algae • Sometimes cell wall has carrageenan: sticky protein used for gelatine capsules & cheese Phylum Chrysophyta – Golden-Brown Algae • Live in fresh water; some in marine habitats • Form cysts in winter • 2 flagella • Have carotenoids • Have chlorophyll A & C • Store energy as oil & aid in formation of petroleum deposits Phylum Bacillariophyta – Diatoms • Made of silicon dioxide (glass-like shell) • Consists of 2 half shells called valves • 2 main shapes o Centric Diatoms: circular or triangular; marine o Pennate Diatoms: rectangular; fresh water • Major producers of oxygen • Shells do not decompose upon death but become diatomaceous earth Phylum Dinoflagellates (Prophyta – Fire Algae) • Unicellular • 2 flagella aligned perpendicular to each other • Cell walls made of cellulose plates • Most photosynthetic; some heterotrophic • Contain carotenoids • Chlorophyll A & C • Genus Noctiluca is bioluminescent • Red tide: forms toxins which reside in shell fish; consumes oxygen in water & kills marine life; blocks sunlight from marine photosynthetic organisms Phylum Euglenophyta – True Eye Algae • Unicellular • Lack cell walls • Highly motile • Fresh water and soil • Contain carotenoids

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Elastic pellicle Eyespot Has contractile vacuoles Euglena raised in the dark end up becoming heterotrophic Reproduction

1. Chlamydomonas (Phylum Chlorophyta) o Asexual  Haploid cell divides through mitosis several times to produce 2-8 daughter zoospores; they develop inside the parent and hatch when mature o Sexual  Haploid cells undergo mitosis to form + or – gametes  + or – gametes show physically similar but biochemically different  Gametes fuse together and form a diploid zygote that has a zygospore (protective cell wall) which protects against harsh conditions & come out when ready; zygospore divides by meiosis to form haploid cells 2. Diatoms o Asexual  Diatoms have 2 half shells  Shells will split in half and each will grow the missing half o Sexual  Undergo meiosis to form + and – gametes  Gametes fuse to form 2n zygote 3. Spyrogyra (Phylum Chlorophyta) o Conjugation tube forms between filaments o + gamete moves across to fuse with – gamete o Forms a zygote with thick walls o Zygote falls off the filament called a resting spore which grows into new filament 4. Oedogonium o Filamentous o Male gametangia: antheridium; female gametangia: oogonium o Flagellated sperm swims in the water & enters a small hole in the oogonium o Fuses to form a zygote which has a thick wall – called resting spore o Resting spore undergoes meiosis to form 4 new haploid zoospores that are released and land to become new filaments 5. Ulva (Phylum Chlorophyta) o multicellular o Gametophyte: haploid gametes o Sporophyte: diploid gametes o 2 cycles of multicellular divisions 1. Stage 1  Sporophyte produce reproductive cells called sporangia  Sporangia go through meiosis to form haploid zoospores

 Zoospores undergo mitosis to form motile spores  Spores land to grow into gametophytes 2. Stage 2  Gametophyte produces + and – gametes  Gametes will fuse to produce a haploid zygote  Zygote lands to form a sporophyte