Kingdom Protista

Outline• Phylum Chlorophyta• Phylum Chromophyta• Phylum Rhodophyta• Phylum Euglenophyta• Phylum Dinophyta• Phylum Cryptophyta• Phylum Prymnesiophyta• Phylum Charophyta• Phylum Myxomycota• Phylum Dictyosteliomycota• Phylum Oomycota

Features of Kingdom Protista

• Members are eukaryotic cells: unicellular, multicellular, or occur as colonies or filaments.

• Individual life cycles vary considerably, but reproduction is generally by cell division and sexual processes.

• Most multicellular members produce some motile cells.

• Mode of nutrition is photosynthetic, ingestive, or combination of both.

Phylum Chlorophyta

• The Green Algae Includes about 7,500 species that occur in

a rich variety of forms and occur in diverse, widespread habitats.

- Greatest variety found in freshwater lakes, ponds, and streams.

- Most have a single nucleus.- Most reproduce both sexually and

asexually.

Phylum Chlorophyta

• Chlamydomonas Common inhabitant of freshwater pools. Pair of whip-like flagella on one end pull

the cell through the water. Red eye spot on the chloroplast and is

sensitive to light. Single, cup-shaped chloroplast with one or

two pyrenoids inside.- Proteinaceous structures thought to

contain starch synthesis enzymes.

Chlamydomonas

Chlamydomonas

• Asexual Reproduction

- Cells are haploid (n) Nucleus divides by mitosis, and cell

contents become two daughter cells within the cellulose wall.

- Develop flagella and swim away.

• Sexual Reproduction

- Under certain environmental conditions, pairs of cells (n) are attracted to each other and function as gametes.

- Protoplasts fuse to form a diploid zygote (2n).

- Diploid zygotes undergo meiosis (genetic recombination), producing four haploid (n) zoopsores.

Sexual Life Cycle of Chlamydomonas

Phylum Chlorophyta

• Ulothrix Thread-like alga.

- Single row of cylindrical cells forming a filament.

Basal cell functions as a holdfast.

- Nucleus is surrounded by a curved, somewhat flattened chloroplast, which contains one or more pyrenoids.

Asexual Reproduction- Protoplasts of any cell but the holdfast can clump,

undergo mitosis, and give rise to zoopsopres with four flagella.

- Zoopsores swim away then settle, lose their flagella and start dividing producing two cells. One cell becomes holdfast and the other continues to divide to for a filament.

- Zoopsores sometimes don’t produce flagella (autospores) while the zoospores that have the capacity to become motile are called aplanospores.

Sexual Reproduction (isogamy)• Asexual and sexual reproduction satrt the same

way.• The contents of any cells may divide by mitosis to

produce up to 64 Zoosporelike cells, each with 2 flagella. These cells act as gametes and fuse in pairs with cells from other filament to produce zygotes (2n).

• Zygotes are dormant with thick walls but conditions are favorable they divide by meiosis to produce 4 haploid zoospores that can divide by mitosis to produce a new filament.

Ulothrix Life Cycle

Phylum Chlorophyta

• Spirogyra (Watersilk) Common freshwater algae consisting of unbranched filaments of

cylindrical cells.- Frequently float in masses at the surface of quiet waters.- Chloroplasts are long and ribbon-shaped.

Asexual Reproduction- No not form zoospores. Any cell capable of division.

- Fragmentation of existing filaments. Sexual Reproduction (oogamy)

- Papillae from adjacent filaments fuse to form conjugation tubes.- Condensed protoplasts function as gametes.- Zygotes develop thick walls and remain dormant, often over

winter.- Protoplasts undergo meiosis, producing four haploid cells.

Spirogyra Sexual Reproduction

Phylum Chlorophyta

• Oedogonium (pronounced ee-doh-goh-nee-um) Epiphytic (not parasitic) filamentous green alga.

- Each cell contains a large, netlike chloroplast that rolls and forms a tube around and toward the periphery of each protoplast.

- Terminal cell of each filament is rounded.

Asexual Reproduction:

- By means of zoospores or fragmentation.- Each zoopsore has about 120 small flagella forming a fringe.

Sexual Reproduction:

- Short antheridia are formed in the filaments.- Pair of sperms produced in each antheridium.- Oogonia, swollen roundish cells, each contain a single egg. In some

species of Oedogonium, oogonia are produced only on female filaments, and antheridia are produced only on only on male filaments.

- As egg matures, a pore develops on the side of the oogonium.- A sperm enters the pore and unites with the egg to form a zygote.- Zygotes may become dormant, but each will produce four zoospores by

meiosis.

Fig. 18.7

Phylum Chlorophyta

• Other Green Algae Chorella - Widespread green alga

composed of tiny spherical cells.- Reproduce by forming either daughter

cells or autospores through mitosis. Desmids - Mostly free-floating and

unicellular.- Reproduce by conjugation.

Fig. 18.8

Fig. 18.10

Phylum Chlorophyta

• Other Green Algae Hydrodictyon (Water Nets) - Net-like,

tubular colonies with hexagonal or polygonal meshes.

- Asexual reproduction as well as isogamous sexual reproduction.

Volvox - Colonial green algae held together in a secretion of gelatinous material

- Reproduction asexual or sexual.

Fig. 18.9

Fig. 18.2a

Phylum Chlorophyta

• Other Green Algae Ulva (Sea Lettuce) - Multicellular seaweed

with flattened green blades.- Isomorphic reproductive structures.

Cladophora - Branched, filamentous green alga with species represented in both fresh and marine waters.

- Mostly multinucleate.

Fig. 18.11

Phylum Chromophyta

• The Brown Algae (Phaeophyceae) Includes 1,500-2,000 species Relatively Large Most Marine None are unicellular or colonial Many have a thallus differentiated into a holdfast, a stipe,

and blades.- Blades may have gas-filled bladders.- Chloroplasts have chlorophylls a and c and the

brownish pigment fucoxanthin- Carbohydrate food reserve is laminarin- Cell walls contain algin (alginic acid)

Sargassum - Floating brown seaweed plentiful in tropical waters near Bermuda.

Brown Alga Nereocystis

Fig. 18.16

Fig. 18.18

Fucus - Common Rockweed• Has separate male and female thalli.• Puffy fertile areas (receptacles) develop at

the tips of the thalli.• Receptacles have pores leading to hollow

chambers called conceptacles.• Gametangia are formed in conceptacles:

- Eight eggs produced in each oogonium.

- 64 sperms produced in each antheridium.

Phylum Rhodophyta

• The Red Algae More than 5,000 species and most species are

seaweed.- Tend to occur in warmer and deeper waters

than brown algae. Most are filamentous. Relatively complex life cycle involving three

types of thallus structures. Colors mostly due to phycobilins. Numbers of species produce agar. Red to purple in color due to phycobilins. Chloroplasts contain chlorophylls a and d. Carbohydrate food reserve is floridean starch.

Fig. 18.21

Reproduction in Polysiphonia• Three types of thalli all resemble each other• Spermatangia attached to male gametophyte thallus and

functions as non-motile male gamete or spermatium.• Carpogonia produced on female gametophyte thallus. Each

carpogonium consists of a single bottle-shaped cell with long neck called the trichogyne. A single nucleus at the base of the carposgonium functions as the egg.

• Zygote develops into cluster of carposporangia toward the base of the carpocyst.- Carpospores (diploid asexual spores) are produced).- When settled in an appropriate location, carpospore germinates and develops into a tetrasporophyte.- Tetrasporangia form along branches of the tetratsporophyte.- Each tetrasporangium undergoes meiosis, giving rise to four haploid tetraspores.- When tetraspores germinate, they give rise to male or female gametophyte.

Human and Ecological Relevance of Algae• A. Chlorella, important protein source

B. Algin• 1. Ability to regulate water behavior in a number of products• 2. Thickening agent• • pastry fillings, gravies, flavored syrups• 3. Emulsifier and suspension agent• • salad dressings and barbecue sauces• 4. Stabilizer• • chocolate drinks, ice cream, coffee creamers• 5. Paper coating• • inks adhere better to paper• 6. Pharmaceuticals and cosmetics• • binder in pills, cough syrups• 7. Brewing• • creamier beer foam with smaller, longer-lasting bubbles

Human and Ecological Relevance Algae

• C. Minerals and Food

• 1. Kelps contain a high concentration of iodine• 2. Kelps can be used as fertilizers• • high content of nitrogen and potassium• 3. Dulse, purple laver, and Irish moss used as food• 4. Carrageenan used as a thickening agent• 5. Funori is used as laundry starch or adhesive in hair dressings

• D. Agar

• 1. Produced most abundantly by the red alga Gelidium• 2. Culture medium for bacterial growth• 3. With added nutrients, can be used as culture medium for

both plant and animal cells

• E. Potential Medicinal Uses

Phylum Myxomycota

• The Plasmodial Slime Molds

- Their habitat are rotten leaves and tree barks. Totally without chlorophyll and are incapable of

producing their own food.- Distinctly animal-like during much of life cycle,

but fungus-like during reproduction. Plasmodium converts into separate small

sporangia (each containing spores) during times of significant environmental changes.

Fig. 18.33

Phylum Dictyosteliomycota

• The Cellular Slime Molds About two dozen species of cellular slime

molds are not closely related to the other slime molds.

- Individual amoebalike cells feed independently, dividing and producing separate new cells periodically.

Human and Ecological Relevance- Break down organic particles to simpler

substances (decomposers).

Phylum Oomycota

• The Water Molds Habitat is aquatic organic material. Form

cottony growths on fish, dead insects. Range in form from single spherical cells

to branching, threadlike, coenocytic hyphae.

- Coenocytic hyphae (not divided into individual cells) may form large thread masses (mycelia).

Reproduction in water moldsAsexual:- Crosswalls form just below the tips of certain

hyphae. Numerous zoospores, each with two flagella, are produced in these special chambers. Zoopsores, after emerging through a terminal pore, give rise to a new mycelia

Sexual:- Involves oogonia and antheridia where

meiosis occurs.

Review• Phylum Chlorophyta• Phylum Chromophyta• Phylum Rhodophyta• Phylum Euglenophyta• Phylum Dinophyta• Phylum Cryptophyta• Phylum Prymnesiophyta• Phylum Charophyta• Phylum Myxomycota• Phylum Dictyosteliomycota• Phylum Oomycota

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