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Chapter 20: Protists

Chapter 20: Protists. Biology- Kirby. 20-1: The Kingdom Protista. Protist- any organism that is not a plant, animal, fungus, or prokaryote. Protists are eukaryotes, and most are unicellular. The first eukaryotic organisms on Earth were protists (1.5 billion years ago).

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Chapter 20: Protists

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  1. Chapter 20: Protists Biology- Kirby

  2. 20-1: The Kingdom Protista • Protist- any organism that is not a plant, animal, fungus, or prokaryote. • Protists are eukaryotes, and most are unicellular. • The first eukaryotic organisms on Earth were protists (1.5 billion years ago).

  3. 20-1: The Kingdom Protista • 3 types of protists: • Animallike- heterotrophs • Plantlike- autotrophs • Funguslike- external digestion such as decomposers or parasites.

  4. 20-2: Animallike Protists: Protozoans • There are 4 types of protozoans classified by their movement: • Zooflagellates • Sarcodines • Ciliates • Sporozoans

  5. 20-2: Animallike Protists: Protozoans • Zooflagellates- move through aquatic environments with flagella. • They can have more than 1 flagella. • Able to absorb food through cell membrane. • Most reproduce asexually by mitosis and cytokinesis. • Some reproduce sexually by meiosis and the formation of gametes.

  6. 20-2: Animallike Protists: Protozoans • Sarcodines- use pseudopods for feeding and movement. • Pseupod- “false foot” • Example: Amoeba- capture and digest food by forming a food vacuole with its cytoplasm. • They reproduce by mitosis and cytokinesis.

  7. 20-2: Animallike Protists: Protozoans • Ciliates- use cilia for feeding and movement. • Cilia- short hairlike projections similar to flagella. Cilia move together, or beat, and move the organism very quickly. • Example: Paramecium- have a macronucleus and a micronucleus. • Cilia sweep food into the gullet.

  8. 20-2: Animallike Protists: Protozoans • Continued: • Waste exit through an anal pore in the membrane. • A cavity called contractile vacuole holds and expels water. • Usually reproduce asexually by mitosis and cytokinesis. Under stress, paramecium undergo conjugation.

  9. 20-2: Animallike Protists: Protozoans • Sporozoans- do not move on their own; parasitic. • Attaches itself to a host and lives inside it. • Some animallike protists cause diseases like malaria and African sleeping sickness. • Others are beneficial to organisms.

  10. 20-2: Animallike Protists: Protozoans • Zooflagellates • Sarcodines • Ciliates • Sporozoans

  11. 20-3: Plantlike Protists-Unicellular Algae • Plantlike protists are called algae. • They contain chlorophyll which makes them appear green. • Some scientists think algae are more closely related to plants; but we consider them to be protists.

  12. 20-3: Plantlike Protists-Unicellular Algae • Accessory pigments- absorb light at different wavelengths than chlorophyll- give algae a range of color. • There are 4 phyla of unicellular algae: • Euglenophytes • Chrysophytes • Diatoms • Dinoflagellates

  13. 20-3: Plantlike Protists-Unicellular Algae • Euglenophytes: • Plantlike protists that have 2 flagella and no cell wall. • Have an eyespot which allows the organism to find sunlight. • Can also live as heterotrophs by absorbing nutrients.

  14. 20-3: Plantlike Protists-Unicellular Algae • Chrysophytes: • Means “golden plants” because they have gold-colored chloroplasts. • Diatoms: • Produce thin cell walls made of silicon which make the walls look like glass.

  15. 20-3: Plantlike Protists-Unicellular Algae • Dinoflagellates: • Half are autotrophs, half are heterotrophs. • Many are luminescent and give off light when agitated by sudden movement in water.

  16. 20-4: Plantlike Protists-Red, Brown, & Green Algae • There are 3 phyla of multicellular algae: • Red algae • Brown algae • Green algae

  17. 20-4: Plantlike Protists-Red, Brown, & Green Algae • Red algae: • Able to live deep in the water. • Have chlorophyll a and reddish accessory pigments called phycobilins. • Important to the formation of coral reefs.

  18. 20-4: Plantlike Protists-Red, Brown, & Green Algae • Brown algae: • Contain chlorophyll a and c, and a brown accessory pigment called fucoxanthin. • Largest and most complex of the algae. • Live in cool, shallow waters.

  19. 20-4: Plantlike Protists-Red, Brown, & Green Algae • Green algae: • Contain chlorophyll a and b, and cellulose in cell walls. • Live in fresh and salt water. • Unicellular green algae- 2 flagella & single chloroplast. • Colonial green algae- cells are stacked. • Multicellular green algae- has specialized cells & lives on rocky coasts.

  20. 20-4: Plantlike Protists-Red, Brown, & Green Algae • Green algae Reproduction: • Life cycle includes both a diploid and haploid generation.

  21. 20-5: Funguslike Protists • Funguslike protists are heterotrophs that absorb nutrients from dead/decaying matter. • Slime molds- funguslike protists that recycle organic material. • Cellular slime molds- individual cells remain separated during life cycle. • Acellular slime molds- cells fuse to form large cells with many nuclei called plasmodia.

  22. 20-5: Funguslike Protists • Water molds- thrive on dead/decaying matter in water & some are plant parasites on land. • Produce thin filaments called hyphae which aid in reproduction. • Slime and water molds are very beneficial because they help decompose matter, but some can cause plant diseases.

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