protists science grade 7

Protists

- a protist is a one- or many- celled organism that lives in wet surroundings.

- all protists have eukaryotic cells (cells with a nucleus and other membrane-bound organelles)

- protists may be plant-like, animal-like, or fungus-like

(Copy Table 1 on page 211)

- Some protists reproduce asexually, resulting in genetically identical offspring

- Some protists reproduce sexually, and produce genetically different offspring

- Scientists think that protists evolved from a one-celled organism with a nucleus and other structures.

• - Plantlike protists have cell walls and contain chlorophyll

• - Animal-like protists are separated into groups according to how they move

• - Funguslike protists have characteristics found in both fungi and protists

• Algae are plantlike protists. - algae contain chlorophyll and produce oxygen as a

result of photosynthesis

- There are many different types of algae. They include diatoms, dinoflagellates, red or green algae commonly called seaweed, and brown algae known as kelp.

• - Dinoflagellates have two flagellum, long, thin, whiplike structures used for movement.

• - Protozoans are one-celled, animal-like protists - Protozoans can live in water, soil, and in living or dead organisms

• - Protists called ciliates are covered in cilia, short, thread-like structures that extend from the cell membrane.

• - cilia help the organism to move quickly in any direction.

• - a Paramecium is a ciliate that has two nuclei

• - Paramecium are found in freshwater environments and consume bacteria.

• - Pseudopods are extensions of cytoplasm used by some protists to move through their environment.

• - the word “pseudopod” means “false foot”

http://www.youtube.com/watch?v=PsYpngBG394

• Fungi

- Fungi are organisms that grow in soil and have a cell wall. Because they do not contain chlorophyll or have the structures of plants, they cannot be categorized as plants.

• - Most species of fungi are many-celled

• - Hyphae are the mass of threadlike tubes which form the body of a fungus

• - Most fungi are saprophytes.

- A saprophyte is an organism that gets food by absorbing dead or decaying tissues of other organisms

- Some species of fungi are parasites, obtaining their food directly from living things

• - Fungi can reproduce sexually or asexually. In either case, fungi reproduce through spores

• - A spore is a waterproof reproductive cell that can grow into a new organism.

http://www.youtube.com/watch?v=A1uQ5rXmbO8

• - Common fungi include mushrooms and yeast.

- yeasts can reproduce by budding, a form of asexual reproduction in which a new organism forms on the side of a parent organism.

Lichen• - a lichen is an organism that is made up of

fungus and either a green algae or a cyanobacterium.

- lichens are food sources for many animals. - lichens are used to determine pollution levels in

an area

• http://www.youtube.com/watch?v=Te4qnLkHnS4