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Protists and Fungi. Protists unit objectives. To show mastery in this unit you must be able to: Identify the major characteristics of the Kingdom Protista. Identify the four groups of protozoans. List the main characteristics of each of the four groups. Describe algae
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Protists unit objectives • To show mastery in this unit you must be able to: • Identify the major characteristics of the Kingdom Protista. • Identify the four groups of protozoans. • List the main characteristics of each of the four groups. • Describe algae • Describe molds and mildew
What is a protist? • Can be unicellular or multicellular • Can be microscopic or large • They are all eukaryotes • Some are like animals (protozoans) • All protozoans are unicellular • Some are like plants (algae) • Use photosynthesis to make food • Do not have organs like roots, stems and leaves • Some are like fungi (molds and mildews) • Decompose dead things • Able to move at some point in life • Do not have chitin in their cell walls
Protozoans • Mainly grouped by the way they move • Some use cilia (hair like projections) • Some use flagella (long hair like extension that use a whip like motion • Some use pseudopodia (false feet) send out extensions of their cell membrane • Some are grouped together because tey are parasitic
Four main groups or protozoans: • 1. Amoebas: Shapeless protists • No cell wall • Use pseudopodia to move • Live in moist places and nutrients can diffuse into the cell. • Most reproduce asexually by splitting into two cells • Some take in large particles of food by moving around the particle and using phagocytosis to form a food vacule
2. Flagellates: Protozoans with one or more flagella • Move by whipping the flagella • Some are parasitic (African sleeping sickness is caused by a flagellate) • Some are beneficial (termites depend on flagellates in their guts to help them digest wood)
3. Ciliates: protozoans with cilia • Use cilia to move • Live in aquatic environments • 4. Sporozoans: Parasitic protozoans • Produce spores (reproductive cell that forms without fertilization and produces a new orgnism) • They are all parasitic and live internally in one or more host. • They have complex life cycles • Usually live in the blood stream or intestines so they are close to food.
Algae • What are alage? • They have the following characteristics: • They are photosynthetic with up to four different kinds of chlorophyll • Can be unicellular or multicellular • Called phytoplankton • Major producer of oxygen in oceans and lakes • Six phyla
The six phyla of algae • The unicellular phyla: • 1. Euglenoids: • Lack a cell wall made of cellulose • Make their own food by photosynthesis • No light = no problem they can ingest food also (they are heterotrophs that are also photosynthetic) • Have one or more flagella
2. Diatoms: • Unicellular • Photosynthetic • Shell composed of silica • Contain chlorophyll and carotenoids (gives a golden yellow color) • Food is stored as oil rather than starch • Gives fish that eat them oily taste (candle fish) • Also gives them buoyancy (oil is less dense than water) so they float near the surface closer to the light.
3. Dinoflagellates: • Unicellular • Cell walls are thick cellulose • Photosynthetic: contain chlorophyll, carotenoid, and red pigments. • Two flagella that cause them to spin when moving • Some can be toxic to fish or humans (red tides) see page 530 problem solving
Multicellular algae • 4. Red algae: • Marine seaweed • Has a thallus (body of the algae) • Has a holdfast to anchor to an object (these are not roots) • Has phycobilins which absorb green violet and blue light which are the wavelengths that penetrate the deepest into the ocean. • This allows these algae to grow deeper than many others.
5. Brown algae: • Most live in salt water along rocky shores. • Contains chlorophyll and a carotenoid called fucoxanthin (brown in color) • Some have air bladders that keep their top portion floating near the surface. • Kelp are the largest and they have a holdfast, a stipe, and a blade. • The holdhast anchors to the rock • The stipe acts as a strong connection to the holdfast. • The blade is the large, flat, waving portion of the kelp • Kelp can get long and form forests that are an important part of the ecosystem (sea urchin and oil spill herring stories)
6. Green algae: • Main pigment is chlorophyll • Unicellular or multicellular • Some form colonies (groups of cells that live together in close association) • Reproduce sexually or aexually • Fragmentation: assexual reproduction where a muticellular organism breaks into pieces and the pieces grow into new organisms