1. KINGDOM PROTISTA

2. PROTISTS Very diverse group –>60,000 known species Most are unicellular –Some are colonial –Some are multicellular Not “simple” at the cellular level –A unicellular organism must carry out all basic functions of life within a single cell –Cells within a multicellular organism can become specialized, and need not carry out all such functions

3. Protists show amazing diversity in cell organization, methods of reproduction, metabolic needs and habitats. They inhabit aquatic and terrestrial environments. Protists are the most nutritionally diverse eukaryotic group –Most are aerobic, and possess mitochondria –Some protists are heterotrophic; others are autotrophic

4. Protists are divided into 3 main groups 1.Animal-like protists (Protozoa) 2.Plant-like protists (Algae) 3.Fungus-like protists

5. Animal-like Protists All protozoa are heterotrophic Some absorb nutrients through their cell membrane, whereas others “engulf” larger food particles. Most protozoa are motile and are divided into phyla based on their means of locomotion.

6. Phylum Sarcodina Ancestors lost their permanent motile structures. Found in fresh and salt water and inside the bodies of animals. Some of these cause disease. Reproduction is both sexual and asexual.

7. Types of Reproduction Asexual Reproduction - only one parent is needed, resulting in offspring that are genetically identical to the parent -- clones. Sexual Reproduction - requires two parents who exchange genetic material, resulting in offspring with a mix of inherited genes.

8. The best known sarcodine is the ameba. Amebas are unicellular organisms that continually change shape Move and capture food by pseudopods, or “false feet.” This movement by pseudopods is called amoeboid movement. Amebas reproduce asexually by binary fission. They are commonly found in freshwater ponds, lakes and streams.

9. Ameba Video Clip

11. Amebas can cause disease! They can cause amebic dysentery. Common in tropical regions Lives in the large intestine of humans and feeds on the intestinal wall causing bleeding. A person becomes infected by eating food or water contaminated with the cysts of the ameba.

12. Radiolarians and Forams Also belong to the phylum Sarcodina. Surrounded by protective shells that contain silicon. They have very long thin pseudopods. When these organisms die, their shell settle to the bottom of the ocean.

13. The White Cliffs of Dover are made of old foram shells

14. Phylum Ciliophora e.g., Paramecium Many possess numerous cilia –Motile structures –Beat in synchronized fashion Prey on bacteria, algae, each other ~65% are free-living and motile –Others attach to some substrate –Some form colonies

15. A Microscopic Predator – two ciliates meet for lunch Didinium sp. Paramecium sp.

16. Ciliates Video Clip

17. Cilia are important in movement and to move food into the oral groove. Food particles are enclosed and digested in food vacuoles. Some ciliates have contractile vacuoles which collect and excrete excess water from the cell. Most aquatic protists have a contractile vacuole.

18. Ciliates do not change shape. They have a rigid outer covering called a pellicle that maintains their shape. Beneath the pellicle, some ciliates have trichocysts which are barbed structures that are discharged for defense or capturing of prey.

20. Reproduce sexually and asexually –Similar to most protozoans in this regard Asexual process is “binary fission” –In this process the cell divides into two genetically identical cells. Sexual process is “conjugation” –Two cells join and exchange their micronuclei before the cells divide.

21. CONJUGATION

22. Phylum Zoomastigina Also called the zooflagellates. These protists move by beating a long whip like flagella. Some have one flagella while others may have many. Most are unicellular. Some are free living but most live in the bodies of animals. Reproduce both asexually and sexually.

23. Trypanosoma in Blood – causes African sleeping sickness

24. African Sleeping Sickness The parasite multiplies in the blood and releases toxins that cause fever, weakness and sleepiness. Lives in the blood of wild and domestic animals, but can be passed to humans through a bite from a tsetse fly.

25. Not all zooflagellates are harmful! Another zooflagellate lives in the digestive tract of termites. The protist breaks down the wood that the termite eats and then both absorb the nutrients.

26. Phylum SPOROZOA These are non motile parasitic protozoa. They get their name because they produce spores during asexual reproduction. The spores allow the spread of the parasite to new hosts. The life cycles of sporozoans are complex and involve growth and reproduction in more than one kind of host. The best know members are of the genus Plasmodium, which causes malaria.

27. MALARIA Has infected > 100 million people –~1 million die yearly in Africa alone Shaking, chills, fever, sweats caused by the toxins that are released when the red blood cells of the host are destroyed by the reproducing Plasmodia. –Symptoms subside, but can reoccur. Transmitted to humans by mosquitoes –Females of genus Anopheles Sexual reproduction takes place in the gut of the mosquito and the asexual phase occurs in the liver and blood of the human host.

28. Malaria Video

29. Life cycle of plasmodium on Pg. 645 of text.