Ch.8 Protists and Fungi Life Science

Section 1 – Protists Learning Objectives 1. Describe the characteristics shared by all protists. 2. Compare and contrast the three groups of protists. 3. List examples of each of the three protist groups. 4. Explain why protists are so difficult to classify.

Section 1 – Protists Protist – eukaryotic, one or many-celled organism which lives in a moist or wet environment  Some are plant-like and contain chlorophyll while others are animal-like and can move

1. Protists reproduce asexually by cell division or regeneration; most protists can also reproduce sexually.

2. Protists are difficult to classify; they are usually grouped based on characteristics shared with plants, animals, or fungi. 3. The evolution of protists is studied through fossils and genetic material.

B. Plantlike protists are called algae; they contain chlorophyll and make their own food.  There are 6 different types of plantlike protists…

1. Diatoms, found in fresh and salt water, make glasslike boxes  Ancient deposits of diatoms are mined and used in insulation, filters, and road paint.

2. Dinoflagellates use flagella (singluar flagellum), long, thin, whiplike structures to move in their saltwater environment. Red tides caused by large number of dinoflagellates

3. Euglenoids have characteristics of both plants and animals. a. When light is present, they can make their own food; an eyespot helps them move toward light. b. In the absence of light, they can eat bacteria or other protists.

4. Red algae, also called seaweeds, are usually many-celled, can live at depths of 200 m, and contain chlorophyll and large amounts of red pigment.

5. Green algae contain large amounts of chlorophyll and can be one-celled or many- celled;  some scientists hypothesize that plants evolved from green algae.

6. A many-celled, saltwater form of brown algae called kelp is an important source of food and shelter for aquatic organisms. Algin, found in the cell walls of brown algae, is gelatinlike. ..used to thicken foods such as ice cream and marshmallows. Algin is also used in making rubber tires and hand lotion.

C. Algae, source of food for ocean organisms, are called the grasses of the ocean. 1. Algae have an environmental impact a. Algae produce oxygen through photosynthesis b. A result of imbalances, an algal bloom can cause environmental problems.

 There are 4 groups of protozoans (animal-like protists) D. One-celled animal protists called protozoans, are classified by how they move.  There are 4 groups of protozoans (animal-like protists) 1. Ciliates – threadlike structures called cilia extend from their cell membranes a. A Paramecium has two nuclei; the micronucleus is involved in reproduction while the macronucleus controls other cell functions. b. Ciliates usually eat bacteria.

2. Flagellates move by whipping their long flagella. a. Many flagellates live in freshwater, and some are parasites. b. Proterospongia grow in cell colonies and have cells that are similar in structure to cells in sponges.

3. Some protozoans move and eat using pseudopods “false feet,” temporary extensions of their cytoplasm. a. An amoeba traps its food with its pseudopods. b. Some shelled protozoans can push a pseudopod through a hole in the shell.

4. One group of protozoans has no way to move on its own a. These protozoans are parasites in humans and other animals. b. Their complex life cylce may have them living a part of their life in one animal and another part in a different animal.

E. Protozoans are important food sources for many animals. 1. Shelled protozoans become a part of sediment layers… …geologists can use them as an indicator species to help locate petroleum reserves (oil).

2. Some parasites can cause diseases in humans. Example: A flagellated parasite called Giardia can be found in water that is contaminated. If you drink water directly from a stream, you could get this diarrhea-causing parasite.

F. Funguslike protists produce spores and must take in food from outside their body… ...many like the amoeba, can move using pseudopods. (2 types of funguslike protists)

1. Slime molds are often found on decaying vegetation in moist, cool, areas.

2. Water molds live in wet places; downy mildews can weaken or kill plants.  One of the most well-known members of downy mildews caused the Irish potato famine during the 1840s.

3. Some funguslike protists help break down dead organisms; many cause diseases in plants and animals.

Discussion Question Protists are classified according to characteristics shared by what three groups of organisms?

Discussion Question Protists are classified according to characteristics shared by what three groups of organisms?  Plants  Animals  Fungi

Section 2 – Fungi Learning Objectives 1. Identify the characteristics shared by all fungi. 2. Classify fungi into groups based on their methods of reproduction. 3. Differentiate between the imperfect fungi and all other fungi.

Section 2 – Fungi A. Fungi can be food sources or ingredients  They can also grow on spoiling food or in damp places like a shower curtain

1. Scientists are not sure how fungi are related to other organisms. a. Threadlike tubes called hyphae produce enzymes for digestion.

b. Most fungi are saprophytes (decomposers), feeding on dead or decaying material Some fungi are parasites, obtaining food directly from living things

2. Fungi grow anchored to soil like plants, but do not make their own food! (They do not have leaves or true roots) They grow best in warm, humid places

3. Fungi can reproduce both sexually and asexually a. In asexual reproduction, cell division produces spores. (genetically the same)

b. In sexual reproduction, the hyphae of two genetically different fungi of the same species produce spores that differ genetically from both parents.

B. Fungi are classified into three groups based on the types of structures formed by the joining of hyphae.  The mushrooms you see above the ground are only the reproductive structures to release spores….MOST of a fungus grows underground or in a rotting tree as hyphae

1. Club fungi produce spores in a club-shaped structure called a basidium.

2. Sac fungi produce spores in a small, saclike structure called an ascus. Yeasts can also reproduce by budding.

3. A zygospore fungus produces spores in a round case called a sporangium.

4. Some fungi, like penicillin, are called imperfect because they have never been observed reproducing sexually or they only reproduce asexually.

C. Lichens are organisms composed of a fungus and either a green algae or a cyanobacterium They can appear crusty, leafy, or grow upright

1. Lichens can be an important food source for animals 2. Lichens help rocks weather, or break down. 3. Since lichens are sensitive, they help scientists monitor pollution levels

D. Some fungi form a hyphae network with plant roots called mycorrhizae. This may have allowed plants to move from water to land about 500 million years ago

E. Some fungi, such as cultivated mushrooms, are food sources

1. Many fungi cause animal and plant diseases, but they also produce antibiotics, such as penicillin, which can fight disease. 2. Fungi are important as decomposers, recycling organic matter.

Discussion Question Why are lichens important?

Discussion Question Why are lichens important? A food source for animals Weathering (break-down) of rocks Tool to monitor pollution