Unit 6 Microorganisms & Fungi

1. Unit 6 Microorganisms & Fungi Ch. 20 Protists

2. What Is a Protist? • Protist - any organism that is not a plant, an animal, a fungus, or a prokaryote • Protists are eukaryotes that are not members of the kingdoms Plantae, Animalia, or Fungi

3. What Is a Protist? • Protists are a diverse group of mainly single-celled eukarytoes

4. Animallike Protists: Protozoans • Zooflagellates - animallike protists that swim using flagella • Most reproduce asexually resulting in 2 genetically identical cells

5. Animallike Protists: Protozoans • Sarcodines - animallike protists that use pseudopods for feeding & movement • Pseudopods - temporary cytoplasmic projections

6. Animallike Protists: Protozoans • Amoeboid movement - when the cytoplasm of the cell streams into the pseudopod, & the rest of the cell follows • Food vacuole - a small cavity in the cytoplasm that temporarily stores food

7. Animallike Protists: Protozoans • Ciliates - use cilia for feeding & movement • Cilia - short, hairlike projections similar to flagella

8. Animallike Protists: Protozoans - Trichocysts - small, bottle-shaped structures used for defense • Macronucleus - a genetic “library”, where multiple copies of most of the genes the cell needs in its day-to-day existence are kept • Micronucleus - a “reserve copy” of all of the cell’s genes

9. Animallike Protists: Protozoans • Gullet - an indentation in 1 side of the organism, where trapped food moves into the food vacuoles • Anal pore - when waste materials are emptied into the environ. • Contractile vacuole - cavities in the cytoplasm that collect water

10. Animallike Protists: Protozoans • Sporozoans - do not move on their own, & are parasitic

11. Animallike Protists & Disease • Some animallike protists cause serious diseases, including malaria & African Sleeping Sickness

12. Malaria • 1 of the world’s most serious infectious diseases • As many as 2 million people die from malaria every year • Its caused by the sporozoan Plasmodium, & carried by the female Anopheles mosquito

14. Ecology of Animallike Protists • Many animallike protists play essential roles in the living world • Some are beneficial to other organisms • Ex.) Termites

15. Plantlike Protists: Unicellular Algae • Many protists contain chlorophyll & carry out photosynthesis

16. Plantlike Protists: Unicellular Algae • Accessory pigments - compounds in algae that absorb light • Chlorophyll & accessory pigments allow algae to harvest & use the energy from sunlight

17. Plantlike Protists: Unicellular Algae • Euglenophytes - plantlike protists that have 2 flagella but no cell wall • Eyespot - cluster of reddish pigment, that helps the organism find sunlight to power photosynthesis • Pellicle - intricate cell membrane

18. Plantlike Protists: Unicellular Algae • Chrysophytes - diverse group of plantlike protists that have gold-colored chloroplasts

19. Plantlike Protists: Unicellular Algae • Diatoms - produce thin, delicate cell walls rich in silicon, the main component of glass

20. Plantlike Protists: Unicellular Algae • Dinoflagellates - generally have 2 flagella, half are photosynthetic & the other half are heterotrophs

21. Ecology of Unicellular Algae • Phytoplankton - the small, photosynthetic organisms found near the surface of the ocean • About 1/2 of the photosynthesis that occurs on Earth is carried out by phytoplankton

22. Ecology of Unicellular Algae • Many protists grow rapidly in regions where sewage is discharged, causing an algal bloom • These algal blooms deplete the water of nutrients, & the cells die in great numbers

23. Plantlike Protists: Red, Brown, & Green Algae • Red algae - able to live at great depths due to their efficiency in harvesting light energy • Red algae contain chlorophyll a & reddish accessory pigments called phycobilins • Phycobilins - good at absorbing blue light, enabling red algae to live deeper in the ocean than many other photosynthetic algae

24. Plantlike Protists: Red, Brown, & Green Algae • Brown algae - contain chlorophyll a & c, as well as a brown accessory pigment, fucoxanthin

25. Plantlike Protists: Red, Brown, & Green Algae • Green algae - share many characteristics with plants, including their photosynthetic pigments & cell wall composition

26. Human Uses of Algae • Algae produce much of earth’s oxygen through photosynthesis • Many species are rich in vitamin C & iron • Chemicals in algae are used to treat stomach ulcers, high blood pressure, arthritis, & other health problems

27. Funguslike Protists • Like fungi, the funguslike protists are heterotrophs that absorb nutrients from dead or decaying organic matter • But unlike most true fungi, funguslike protists have centrioles • They also lack the chitin cell walls of true fungi

28. Funguslike Protists • Slime molds - funguslike protists that play key roles in recycling organic material • Cellular slime molds - individual cells • Acellular slime molds - cells fuse to form large cells with many nuclei

29. Funguslike Protists • Water molds - (oomycetes) - thrive on dead or decaying organic matter in water & some are plant parasites on land

30. Funguslike Protists • An oomycete that produced airborne spores that destroy all or parts of the potato plant, caused the potato famine in Ireland, in the 1840s