1. Protista

2. What are Protists?
eukaryotic organisms of the Protista kingdom- the MOST diverse kingdom
While some people think algae are plants, protozoans are animals, and molds are fungi, they are NOT!

3. Classification
Complexity and diversity of protists make classifications difficult (variety is so great there could be as many as a dozen kingdoms in the future)
Protists are grouped according to modes of nutrition:
Plant-like protists = autotrophs (algae)
Animal-like protists=heterotrophs by ingestion (protozoans, slime molds)
Fungus-like protists= heterotrophs by absorbtion (water molds)

4. Algae Diverse group of photosynthetic protists
Similar to plants because they have chlorophyll a and carry on photosynthesis within a membrane bounded plastid
However- algae do not develop from an embryo, as do all plants
Types of algae:
Green algae
Red algae
Brown algae
Diatoms
Dinoflagellates
Euglenoids

5. Phylum Chlorophyta – Green Algae
Includes 7,500 species of organisms
Inhabit oceans, freshwaters, snow banks, bark of trees, and backs of turtles
Can form symbiotic relationships with fungi, plants, and animals
Majority are unicellular
Green algae contain chlorophyll a & b

6. Chlamydomonas- Unicellular Green Algae
Small, actively moving green algae that inhabits small freshwater ponds
Has a definite cell wall and a single, large, cup-shaped chloroplast
Their chloroplast contain a pyrenoid- a dense body where starch is synthesized
Many species have a bright red eyespot or stigma which are light sensitive and bring organisms to the light for photosynthesis

7. Electron Micrograph of Chlamydomonas

8. Chlamydomonas and Reproduction
Asexual occurs in favorable environments
Mitosis produces as many as 16 daughter cells within the parent cell wall
Each daughter cell that secretes a cell wall and acquires a flagella
They escape by digesting the parent cell wall
Sexual occurs in hostile environments
2 gametes come into contact and form a zygote
Heavy wall forms around the zygote and it becomes a resistant zygospore
Undergoes a period of dormancy
When zygote germinates, it produces 4 zoospores by meiosis
Zoospores = flagellated spores

9. Life Cycle of Chlamydomonas

10. Red Algae – The Rhodophyta
Multicellular
About 5,000 species
Live mostly in warmer seawater, some as deep as 200 m
Economic Importance
Agar - capsules; dental impressions; cosmetics; culture medium; electrophoresis; food prep.
Carrageen - an emulsifying agent used in chocolate, low-fat foods, & cosmetics
The reddish-black wrappings around sushi rolls consist of processed Porphyra blades

11. Brown Algae – The Phaeophyta
About 1,500 species
Most live in colder ocean waters along rocky coasts
No unicellular or colonial brown forms
Morphology:
Some small forms with simple filaments
Others large multicellular forms that may exceed 200 m in length
Pigments:
Chlorophylls a and c
Fucoxanthin (a type of carotinoid pigment) gives them their color
Excess food stored as a carbohydrate called laminarin

12. The Phaeophyta
Multicellular forms of green, red, and brown algae are called seaweeds
Laminaria (a kelp), and Fucus, (rockweed), are common intertidal seaweeds
Nereocystis and Macrocystis often form forest-like thickets in deeper waters
Sargassum forms floating masses where other organisms find shelter
Harvested for food and fertilizer
Macrocystis is source of algin, a thickener for foods

13. Brown Algae

14. Protozoans - Animal-like Protistas
Protozoan: unicellular/colonial Eukaryote
Includes photsynthetic and heterotrophic organisms.
Most have a way to move ( flagella, pseudopod, or cilia.

15. Zooflagellates – Phylum Zoomastigophora4
Colorless heterotrophs
Most symbiotic and many parasitic
Well known for causing various diseases in humans
Trypanosoma
African sleeping sickness - Tsetse fly
Chagas disease – Kissing bug
Giardia lamblia
Most common flagellate in human digestive tract
Causes severe diarrhea
Cysts are transmitted in contaminated water
Beavers are important reservoir hosts

16. Zooflagellates

17. Giardia lamblia

18. Pseudopods
Pseudopods form when cytoplasm streams forward in a particular direction
Amoeboids (phylum Rhizopoda) are protists that move and ingest their food with pseudopods
Phagocytize food
Entamoeba histolytica - a parasite of the human colon;
Causes amoebic dysentery
Can be fatal
Foraminiferans (phylum Foraminifera) and radiolarians (phlyum Actinopoda)
Both have a skeleton (test) of either calcite or silica

19. Pseudopods

20. The Ciliates – Phylum Ciliophora
Ciliates are one of the most complex protozoan
Hundreds of cilia beat in coordinated rhythm
Most are holozoic (swallow food whole)
Divide by transverse binary fission during asexual reproduction
Two nuclei of differing types
Micronucleus – Heredity
Macronucleus – Metabolism

21. Ciliates

22. Sporozoans – Phylum Apicomplexa
Consists of 3,900 species nonmotile, parasitic, spore-forming protozoans
One of the most serious parasitic human diseases is malaria Plasmodium spp
Kills 3,000,000 people each year
Transmitted by mosquito
Toxoplasma
Humans get from cats
Causes birth defects and mental retardation when pregnant mom exposed

23. Life Cycle of Plasmodium vivax

24. Slime Molds and Water Molds
Slime Molds - dispose of dead plant material (phagocytic) and feed on bacteria (keep bacteria population down).
Water Molds – decompose remains and are parasites
WHY they are NOT Fungus:
Water mold’s cell wall contains cellulose instead of chitin (fungus) and The organism is diploid (not haploid as in the fungi)
Have flagellated cells
Slime Molds can also be categorized as protozoan because they are heterotrophic by ingestion (water molds are heterotrophic by absorption)

25. Life Cycle of Plasmodial Slime Molds and Cellular Slime Mold
Plasmodial - Phylum Myxomycota
Body in the form of a plasmodium
Diploid, multinucleated, cytoplasmic mass
Enveloped by a slimy sheath
Eventually produces sporangium which in turn produces spores
Cellular - Phylum Acrasiomycota
Body in the form of individual amoeboid cells
Later aggregate into pseudoplasmodium which then forms sporangium & spores

26. Plasmodial Slime Molds

27. Water Molds - Phylum Oomycota
Most live in the water where they form furry growths when they parasitize or decompose
Phylum name refers to the enlarged tips (called oogonia) where eggs are produced
Body filamentous, appearing like true Fungi
Examples:
Phytophthora infestans caused the 1840’s potato famine in Ireland
Saprolegnia is often seen as a white, cotton-like coating on dead aquarium fish

28. Water Mold