Chapter 15 Lecture Outline Kingdom Protista Copyright The

Chapter 15 Lecture Outline Kingdom Protista Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display.

Outline v Introduction v Features of Kingdom Protista v Algae v Phylum Chlorophyta – The Green Algae v Phylum Chromophyta – The Yellow-Green Algae, Golden-Brown Algae, Diatoms, and Brown Algae v Phylum Rhodophyta – The Red Algae v Phylum Euglenophyta – The Euglenoids v Phylum Dinophyta – The Dinoflagellates v Phylum Cryptophyta – The Cryptomonads v Phylum Prymnesiophyta (Haptophyta) – The Haptophytes v Phylum Charophyta – The Stoneworts v Human and Ecological Relevance of the Algae v Phylum Myxomycota – The Plasmodial Slime Molds v Phylum Dictyosteliomycota – The Cellular Slime Molds v Phylum Oomycota – The Water Molds

Introduction v Less than 1 billion years ago, organisms confined to oceans. • Protected from drying out, ultraviolet radiation, and large fluctuations in temperature • Absorbed nutrients directly from water v About 400 million years ago, green algae began making transition from water to land. • Gave rise to green plants – Coleochaete probably indirect ancestor of land plants. o Shares features with land plants: cells that resemble parenchyma, development of cell plate and phragmoplast during mitosis, a protective covering for zygote, and production of lignin-like compound Coleochaete

Features of Kingdom Protista v Domain Eukarya - All members have eukaryotic cells. • Includes Kingdoms: Protista, Plantae, Fungi, Animalia v Organisms in Protista vary from unicellular to multicellular. • Nutrition varied: photosynthetic, ingestion of food, absorption of food • Individual life cycles vary considerably. • Reproduction generally by cell division and sexual processes. v Algae are in Kingdom Protista. • Grouped into several phyla based on form of reproductive cells, and combinations of pigments and food reserves.

Phylum Chlorophyta v Green algae • Unicellular, filamentous, platelike colonies, netlike tubes, hollow spheres, lettuce-like leaves • Greatest variety in freshwater lakes, ponds, and streams – Some on tree bark, in animal fur, in snowbanks, in flatworms or sponges, on rocks, in lichen “partnerships. ” • Have chlorophylls a and b • Store food as starch • Most have a single nucleus per cell. • Most reproduce both sexually and asexually.

Phylum Chlorophyta v Chlamydomonas • Common inhabitant of freshwater pools • Unicellular • Pair of whip-like flagella on one end pull cell through water. • Two or more vacuoles at base of flagella – Regulate water content of cell and remove waste • Single, cup-shaped chloroplast with one or two pyrenoids inside – Pyrenoids - Proteinaceous structures associated with synthesis of starch • Red eyespot near base of flagella – Allows alga to swim toward light

Phylum Chlorophyta v Chlamydomonas • Asexual reproduction: – Nucleus divides by mitosis, and cell contents become two daughter cells within cellulose wall. o Each develop flagella and swim away. o No change in chromosome number; all cells remain haploid.

Phylum Chlorophyta v Chlamydomonas sexual reproduction: • Meiosis occurs in zygospore, producing 4 haploid zoospores that grow into full-sized algae. • Under certain conditions, cells congregate together. • Two cells fuse together to form zygote, that will become zygospore and may remain dormant.

Phylum Chlorophyta v Ulothrix • Filamentous with holdfast cell at one end • Chloroplast - Wide, curved, somewhat flattened, with one to several pyrenoids • Asexual reproduction: – Cells contents condense, divide by mitosis and become zoospores inside parent cell. – Zoospores escape through pore in parent cell wall. o Resemble Chlamydomonas cells o Grow into new filaments

Phylum Chlorophyta v Ulothrix sexual reproduction: • Cell contents condense and divide by mitosis inside parent cell. • Each new cell produces flagella. • Cells escape from parent cell and become gametes.

Phylum Chlorophyta v Spirogyra (watersilk) • Filaments of cylindrical cells • Frequently floats in masses on surface of quiet freshwater • Chloroplast ribbon-shaped and spirally wrapped around vacuole, with pyrenoids at regular intervals. • Asexual reproduction: – Only by fragmentation of filament

Phylum Chlorophyta v Spirogyra (watersilk) • Sexual reproduction by conjugation. – Papillae fuse and form conjugation tubes. – Condensed protoplast of one filament flows or crawls through tube to adjacent cell. – Protoplasts fuse, forming zygote that develops thick wall. – Eventually zygote undergoes meiosis.

Phylum Chlorophyta v Oedogonium • Epiphytic filamentous green alga with holdfast • Large netlike chloroplast with pyrenoids at intersections of net • Asexual reproduction: – By fragmentation or by zoospores – Zoospores produced singly in cells at tips of filaments. o Have about 120 flagella that form fringe toward one end of zoospore

Phylum Chlorophyta v Oedogonium sexual reproduction: • Exhibits oogamy - One gamete is motile, while other is larger and stationary. – – Antheridium - Boxlike cell that produces two motile sperm Oogonium - Swollen cell containing single egg Sperm enters oogonium through pore. • Zygote forms thick walls and may remain dormant. • Zygote produces 4 zoospores by meiosis that grow into new haploid filaments. •

Phylum Chlorophyta v Other green algae • Chlorella - Widespread green alga composed of tiny spherical cells – Only reproduce asexually by forming either daughter cells or autospores through mitosis – Used in research; may become important as food source • Desmids - Mostly free-floating and unicellular – Reproduce by conjugation Closterium, a desmid

Phylum Chlorophyta v Other green algae • Hydrodictyon (water nets) - Net-like, tubular colonies with hexagonal or polygonal meshes – – Asexual reproduction, as well as isogamous sexual reproduction Isogamous = two flagellated gametes

Phylum Chlorophyta v Other green algae • Acetabularia (mermaid’s wineglass) - Consists of a single, huge cell shaped like a delicate mushroom – Used in classic experiments demonstrating influence of nucleus on form of cell – Isogamous

Phylum Chlorophyta v Other green algae • Volvox - Colonial green algae held together in a secretion of gelatinous material, resembling hollow ball – Reproduction asexual or sexual o Smaller daughter colonies formed inside parent colony

Phylum Chlorophyta v Other green algae • Ulva (sea lettuce) - Multicellular seaweed with flattened green blades and basal holdfast to anchor blades to rocks – – Haploid and diploid blades o Diploid blades produce spores that develop into haploid blades. o Haploid blades bear gametangia that form gametes. o Gametes fuse to form zygotes that grow into diploid blades. Exhibit isomorphism - Haploid and diploid blades indistinguishable.

Phylum Chromophyta v Yellow-green algae (Xanthophyceae) • Mostly freshwater, with a few marine and terrestrial representatives – Two flagella of motile cells are oriented in opposite directions. – Vaucheria - Oogamous, coenocytic, filamentous species o Aplanospores formed during asexual reproduction. o Sexual reproduction rare. Stipitococcus, a yellow-green algae Sexual reproduction in Vaucheria

Phylum Chromophyta v Golden-brown algae (Chrysophyceae) • Most occur in the plankton of fresh water. – Motile cells have two flagella of unequal length inserted at right angles to each other. o Photoreceptor on short flagellum.

Phylum Chromophyta v The Diatoms (Bacillariophyceae) • Unicellular • Fresh and salt water, particularly abundant in cold marine habitats • Also, dominate algal flora on damp cliffs, tree bark or buildings • Look like ornate, glass boxes with lids – As much as 95% of wall is silica. • Chlorophylls a and c and fucoxanthin • Food reserves - Oil, fats or laminarin

Phylum Chromophyta v The Diatoms (Bacillariophyceae) • Asexual reproduction results in half of cells becoming progressively smaller. • Original cell size restored through sexual reproduction.

Phylum Chromophyta v Brown algae (Phaeophyceae) • Relatively large; none unicellular or colonial • Most marine; majority in cold, shallow water, except giant kelp • Many have a thallus differentiated into a holdfast, a stipe, and blades. – Blades may have gas-filled bladders. • Chlorophylls a and c, fucoxanthin • Food reserve = laminarin • Algin in cell walls. Nereocystis, a kelp

Phylum Chromophyta v Brown algae (Phaeophyceae) • Sargassum - Floating brown seaweed • Asexual reproduction by fragmentation or autospores. Sargassum

Phylum Chromophyta v Brown algae (Phaeophyceae) • Fucus - Common rockweed – Sexual reproduction: o Receptacles at tips of branches contain spherical chambers called conceptacles with gametangia inside. « Oogonium produces 8 eggs. « Antheridium produces 64 sperm. o Eggs and sperm released into water.

Phylum Rhodophyta v The red algae • In warmer and deeper waters than brown algae • Most are filamentous with filaments so tightly packed they appear to have flattened blades or branched segments.

Phylum Rhodophyta v The red algae • Relatively complex life cycle involving three types of thallus structures • Nonmotile reproductive cells

Phylum Rhodophyta v The red algae • Colors mostly due to phycobilins. – Similar to those of cyanobacteria o Red algae may have been derived from cyanobacteria. • Chlorophylls a, and sometimes d • Food reserve - Floridean starch • Numbers of species produce agar.

Phylum Euglenophyta v The Euglenoids • No cell wall; pellicle = plasma membrane and underlying strips that spiral around cell • Flagellum pulls cell through water. • Gullet ingests food. • About 1/3 of species have disc -shaped chloroplasts. • Red eyespot for light detection • Paramylon food reserve • Asexual reproduction by cell division. • Sexual reproduction not confirmed.

Phylum Dinophyta v The Dinoflagellates • Red tides - Sudden multiplication of dinoflagellates – Some produce neurotoxins that accumulate in shell fish. • Cellulose “armor plates” inside cell membrane • Two flagella in intersecting grooves – One trails behind cell - Acts as rudder – Other encircles cell at right angles - Gives cell spinning motion

Phylum Dinophyta v The Dinoflagellates • Most have disc-shaped chloroplasts. – Contain xanthophyll pigments – Chlorophylls a and c • About 45% nonphotosynthetic • Chromosomes remain condensed and visible throughout life of cell. • Starch food reserve • Many have tiny projectiles that fire when irritated.

Phylum Cryptophyta v The Cryptomonads • Marine and freshwater • Two flagella • Plates on inside of plasma membrane • Single, two-lobed chloroplast with starch granules surrounding a central pyrenoid • Nucleomorph - Vestigial nucleus of primitive symbiotic organism • Gullet lined with ejectosomes. • Sexual reproduction unknown.

Phylum Prymnesiophyta (Haptophyta) v The Haptophytes • Fresh and saltwater; major component of marine plankton • Most unicellular, with two smooth flagella of similar length inserted at the apex. • Pigments and food reserve similar to Chromophyta. • Haptonema - Third flagellum located between two flagella. – Aids in food capture • Often covered in scales • Two disc-shaped chloroplasts

Phylum Charophyta v The Stoneworts • Shallow, freshwater lakes and ponds • Often precipitate calcium salts on their surfaces • Axis with short lateral branches in whorls. • Sexual reproduction is oogamous. • Multicellular antheridia

Human and Ecological Relevance of Algae v Protistan algal phyla at bottom of food chain. v Diatoms • Oils are sources of vitamins. • Diatomaceous earth v – Filtration – Polishes, toothpaste – Paint that reflects light Other algae • Chlorella – Potential human food source

Human and Ecological Relevance of Algae v Algin • Produced by giant kelps and other brown algae – Ice cream, salad dressing – Latex paint, textiles, ceramics – Regulates water behavior o Controls development of ice crystals o Regulates penetration of water o Stabilizes suspensions Vessel harvesting kelp

Human and Ecological Relevance of Algae v Minerals and food • Iodine from kelp • Red algae v – Food - Dulse, nori – Carrageenan - Thickening agent Agar • Produced by red alga Gelidium – Solidifier of nutrient culture media – Retains moistness in bakery products – Base for cosmetics

Phylum Myxomycota v The Plasmodial slime molds • Without chlorophyll – Feed on bacteria and other organic particles • Consist of a plasmodium – Protoplasm containing many diploid nuclei – No cell wall – Flows rapidly and rhythmically – Found on damp forest debris, under logs, on dead organic material Plasmodium

Phylum Myxomycota v The Plasmodial slime molds • Sexual reproduction: – Plasmodium converts into separate small sporangia that contain spores. Sporangia from various plasmodial slime molds

Phylum Myxomycota v The Plasmodial slime molds • Sexual reproduction: – Meiosis occurs in spores. – Spores grow into myxamoebae that act as gametes and fuse to form zygotes. – Zygotes grow into new plasmodia.

Phylum Dictyosteliomycota v The Cellular slime molds • Individual amoebalike cells feed independently, dividing and producing separate new cells periodically. • Clump together to form mass called pseudoplasmodium v – Crawls like a garden slug – Eventually transforms into sporangium-like mass of spores Human and ecological relevance of the slime molds: – Break down organic particles to simpler substances

Phylum Oomycota v The Water molds • Cottony growths on fish; often found on dead insects • Range in form from single spherical cells to branching, threadlike, coenocytic hyphae – Coenocytic hyphae are not divided into individual cells and may form large thread masses (mycelia). • Share features with brown algae, including oogamy, cellulose in cell walls, predominantly diploid lifecycle, and zoospores with two flagella • Asexual reproduction: – Crosswalls form at tips of hyphae – Zoospores produced inside and emerge through pore.

Phylum Oomycota v The Water molds • Sexual reproduction: – Meiosis takes place in oogonia and antheridia. – Zygotes formed in oogonia give rise to new mycelia. • Human and ecological significance of the water molds: – Downy mildew on grapes – Potato blight o 1846 famine in Ireland

Outline v Introduction v Features of Kingdom Protista v Algae v Phylum Chlorophyta – The Green Algae v Phylum Chromophyta – The Yellow-Green Algae, Golden-Brown Algae, Diatoms, and Brown Algae v Phylum Rhodophyta – The Red Algae v Phylum Euglenophyta – The Euglenoids v Phylum Dinophyta – The Dinoflagellates v Phylum Cryptophyta – The Cryptomonads v Phylum Prymnesiophyta (Haptophyta) – The Haptophytes v Phylum Charophyta – The Stoneworts v Human and Ecological Relevance of the Algae v Phylum Myxomycota – The Plasmodial Slime Molds v Phylum Dictyosteliomycota – The Cellular Slime Molds v Phylum Oomycota – The Water Molds