Protists Chapter 20

1. ProtistsChapter 20 Objective: 11.0 Classify animals according to type of skeletal structure, method of fertilization and reproduction, body symmetry, body coverings, and locomotion. Examples: skeletal structure -—vertebrates, invertebrates; fertilization—- external, internal; reproduction -—sexual, asexual; body symmetry—- bilateral, radial, asymmetrical; body coverings—- feathers, scales, fur; locomotion—- cilia, flagella, pseudopodia

2. What is a Protist? • Any eukaryote that is not an animal, plant, or fungus • Most are unicellular, but not all • Can be classified as animal-like, plant-like, or fungus-like

3. Animal-like Protists(Section12-2) • Heterotrophs • 4 phyla, based on means of movement: • Zooflagellates – swim through their aquatic environments using flagella • Sarcodines – move via temporary cytoplasmic projections called pseudopods • Ciliates – use _________ for feeding and movement • Sporozoans – do not move on their own; are parasites

4. Zooflagellates • Can generally absorb food through their cell membranes • Nutrients from decaying organic matter in water • From the bodies of other organisms in which they live • Reproduction can be asexual by mitosis and cytokinesis, or sexual by meiosis.

5. Sarcodines • Pseudopods are used for feeding and movement. • EX: amoebas • Reproduce asexually by mitosis and cytokinesis Source: http://www.enchantedlearning.com/subjects/protists/amoeba.shtml

6. Ciliates • Cilia are short hair-like projections. • The rapid beating of cilia propels ciliates through water. • Most ciliates contain two different nuclei: • Macronucleus – keeps multiple copies of the genes • Micronucleus – contains a “reserve” copy of all the cell’s genes • Obtain food by using cilia to sweep food into an indentation called the gullet • Reproduce asexually by _____ and _____, and sexually by conjugation.

7. Paramecium Source: http://rookc.pbworks.com/w/page/46197520/Paramecium

8. Sporozoans • Live as parasites on everything from worms to humans • Reproduce by sporozoites

9. Protists and Disease • Malaria – caused by the sporozoanPlasmodium; spread by mosquito bites • African sleeping sickness – caused by zooflagellateTrypanosoma; spread by tsetse fly bites • Amebic dysentery – caused by parasitic Entamoeba • Dysentery – flagellate Giardia

10. Plant-Like Protists: Unicellular Algae(Section 20-3) • Contain chlorophyll and carry out photosynthesis • Commonly called “algae” • Seven major phyla, classified according to a variety of cellular characteristics (types of chlorophyll or accessory pigments present): • First 4 phyla are unicellular • Last 3 contain many multicellular organisms

11. 1. Euglenophytes • Plant-like, but have 2 flagella (like ???) and no cell wall • Eyespot – cluster of reddish pigment that helps organism find sunlight • Reproduce asexually by binary fission Source:http://www.fcps.edu/islandcreekes/ecology/euglena.htm

12. 2. Chrysophytes • “yellow plants” • Includes yellow-green and golden-brown algae • Chloroplasts contain bright yellow pigment

13. 3. Diatoms • Produce thin, delicate cell walls rich in silicon (Si) – the main component of glass. • Look like etched petri dishes Source: http://deepbluehome.blogspot.com/2011/01/psychedelic-diatoms.html

14. 4. Dinoflagellates • About half are photosynthetic; others are heterotrophs • 2 flagella, which wrap around the the organism in grooves • Reproduce asexually by binary fission • Can luminesce when agitated

15. Source:http://biology.unm.edu/ccouncil/Biology_203/Summaries/Protists.htm Source:http://www.asknature.org/strategy/d851e35113506bcf0219e973da169c29

16. Ecology of Unicellular Algae • Compose most of the phytoplankton – plant microorganisms at the bottom of food chains • Algal blooms (“red tide”) – • Protists can break down sewage in water • Excessive waste creates large populations of euglenophytes, which deplete nutrients in the water. • When they die, they can deplete oxygen supplies needed by other organisms.

17. Plant-like Protists: Red, Brown, and Green Algae (Section 20-4) • Mostly multicellular • Reproductive cycles similar to plants • Many with cell walls and photosynthetic pigments identical to plants

18. Red Algae • Phylum Rhodophyta (“red plants”) • Contain chlorophyll  and reddish accessory pigments called phycobilins, which can absorb blue light, allowing them to harvest light energy at great depths • Can actually be green, purple, or redish-black in color • Play a role in coral reef formation • Lack flagella and centrioles

19. Brown Algae • Phylum Phaeophyta (“dusky plants”) • Contain chlorophyll  and c, as well as a brown accessory pigment (fucoxanthin) • Dark yellow-brown color • EX: giant kelp Source:http://landsat.gsfc.nasa.gov/news/news-archive/sci_0033.html

20. Green Algae • Phylum Chlorophyta (“?????”) • Same photosynthetic pigment and cell wall composition as plants • Contain chloroplast a and b • Life cycles of many include both a diploid and a haploid generation (“alternation of generations”)

21. Alternation of Generation Source: http://moodle.rockyview.ab.ca/mod/book/view.php?id=58103&chapterid=21008

22. Fungus-like Protists(Section 20-5) Fungus-like Protists Fungi Both Heterotrophs; Absorb nutrients from dead/decaying matter Cell walls made of chitin Have centrioles

23. Molds • Slime Molds: • Cellular slime molds – individual cells remain distinct (separated by cell membranes) throughout life • Acellular slime molds – pass through a life stage in which cells fuse to form large cells with many nuclei • Water Molds: • Thrive on dead or decaying matter in water OR are plant parasites on land • EX: white fuzz on a dead fish in the water