Chapters 25 and 26 Protists and Fungi

Chapter 25: Protists

Kingdom Protista Kingdom Protista includes more than 50,000 kinds of organisms. They consist of single-celled or simple multicellular eukaryotic organisms that generally do not fit in any other kingdom. Most, but not all are microscopic. First evolved about 2 billion years ago through the endosymbiosis of small and larger prokaryotes.

Characteristics Overall characteristics vary widely: Some are unicellular. Ex: Amoeba Some form colonies. Ex: Volvox Some are multicellular. Ex: Brown Algae Many are autotrophs; making food through photosynthesis Some are heterotrophs; either eating other protists or by decomposing and absorbing nutrients as fungi do. Variety of ways to move: flagella, cilia, or pseudopods

Reproduction Most reproduce asexually by binary fission or multiple fission Binary fission: one cell divides into two identical cells Multiple fission: one cell divides into more than two cells Some reproduce sexually by conjugation Two cells join and exchange genetic material Then each divides to produce four new offspring.

Groups of Protists Three main groups of protists are generally recognized: Animal-like Fungus-like Plant-like

Animal-like Protists Often called Protozoans Unicellular (one-celled) Cannot make food: eat bacteria, algae, and other protozoans Four phyla based on movement: Protozoa, Ciliophora, Sarcomastigophora, and Apicomplexa

Phylum Protozoa Move and feed by using finger-like projections called pseudopods Most live in freshwater. All change shape as they move. Example: Amoeba Amoeba feeding on a bacterial cell.

Phylum Ciliophora Move by tiny hair-like structures called cilia. Most live in freshwater. Slipper-shaped. Surrounded by a membrane-like structure called a pellicle. All have two nuclei: macronucleus (controls most cell activities) and micronucleus (controls reproduction) Ex: Paramecium Contractile vacuole controls water movement in and out. Feed through oral groove

Phylum Sarcomastigophora Move by using a whip-like tail called a flagella. Some have one flagella, others have many. Live in fresh or salt water or as disease-causing parasites in animals. Example: Trypanosome flagellate causes African Sleeping Sickness. It is transmitted by the bite of the tsetse fly. Trypanosome flagellate Tsetse fly

Phylum Apicomplexa Also known as sporozoans. Animal-like protists that live as parasites. Can not move on their own. Most feed on the blood of human or animal hosts. Malaria is caused by a sporozoan called Plasmodium. It is transmitted by the bite of the Anopheles mosquito. The plasmodium produce poisons that cause fever and chills. Sporozoans Anopheles mosquito

Plant-like Protists Also known as algae. Can be single-celled, many-celled or live in colonies. All contain chlorophyll and can make food. Some contain other colored pigments as well. Classified into seven phyla based on the pigments they contain and the number of cells

Characteristics of Algae Important part of the microscopic plants and animals found floating near the surface of water known as plankton. Plant-like plankton that makes its own food is called phytoplankton. It is responsible for producing about 90% of the earth’s oxygen as well as being an important part of the food chain.

Phylum Chlorophyta Green Algae Ancestors of green plants. Contain chlorophyll a and b and store food as starch. Most species are freshwater and can be single-celled, live in colonies, or in filamentous, multicellular forms Salt-water species are many celled. Volvox Ulva Spirogyra

Phylum Phaeophyta Brown Algae Contains chlorophylls a and c Saltwater algae known as seaweed or kelp. Common along rock coast lines in cold water. Grow very large (100m) Many have small, light-colored structures called air bladders to keep them floating near the surface.

Phylum Rhodophyta Red Algae Contain chlorophyll a and phycobilins that allow them to absorb wavelengths of light from deep water. Also called seaweed. Found in deep ocean water. Used to make agar, and in pudding, ice cream, cheese, salad dressing and marshmallows

Phylum Bacillariophyta Diatoms Yellow or brown in color. Come in many shapes and patterns. Covered by shells that are made of a glass-like substance known as silica. These shells are used in toothpaste, silver polish, detergents, insulation and road paint.

Phylum Dinoflagellata Fire algae Many are red in color. Found in salt water. Most have two flagella and spin as they move Responsible for red-tides (Ocean turns red because of a population explosion of fire algae. The algae produce poisons that can kill fish and people).

Phylum Chrysophyta Golden Algae Most live in freshwater Form highly resistant cysts to survive in frozen or dried up lake beds Store energy as oil Probably play a role in formation of petroleum deposits

Phylum Euglenophyta Euglenoids Have both plant and animal like characteristics. Can make food when light is present. Can eat food when it is not. Have an eyespot that responds to light (swims toward it). Move by using a flagella

Fungus-like Protists Fungus-like protists —also known as slime molds and water molds. They have features of both protists and fungi. Four phyla: Phylum Myxomycota: Plasmodial Slime Mold Phylum Dictyostelida: Cellular Slime Mold Phylum Oomycota: Water mold Phylum Chytridiomycota: Water mold

Slime Molds Slime molds —two stage life cycle: Plasmodial slime mold Reproductive stage: resembles a fungus Feeding stage: resembles an amoeba (protist) During the feeding stage, slime molds appear in one of two forms: plasmodial slime molds (consisting of a large mass of cytoplasm with many nuclei); and cellular slime molds (consisting of individual amoebalike cells). Plasmodial slime mold Cellular slime mold

Water Molds Most are parasitic and grow as long filaments on the host, eventually harming them.

Chapter 26: Fungi

Kingdom Fungi Kingdom Fungi — consists of many-celled organisms that can not make food and can not move around. Do not have chlorophyll. Most get food by decomposing and absorbing dead organic matter (saprophytes). Some get food from living host organisms (parasites). Fungi do not have roots, leaves or tissue layers. Store energy in the form of glycogen.

Fungus Structure The body of a fungus is made of a mass of thread-like tubes known as hyphae. Hyphae usually grow underground and may join to form above ground reproductive structures like mushroom caps. Cell walls made of chitin. Grow best in warm, moist places. Reproduce by forming spores.

Phylum Zygomycota Zygote Fungi: spores are produced in round spore cases called sporangia. Example: Bread mold

Phylum Basidiomycota Club Fungi: spores are produced in a club-shaped structure called a basidium (pl. basidia) Examples: mushrooms and rusts

Phylum Ascomycota Sac Fungi: spores are produced in a sac-like structure called an ascus (pl. asci) Examples: yeasts, molds, morels and truffles

Phylum Deuteromycota Imperfect Fungi: reproductive stage has never been observed. Examples: ringworm fungus, athletes foot fungus and Penicillium (used to make Penicillin). Ringworm infection Athletes foot infection

Micorrhizae A micorrhiza is a symbiotic structure formed by a fungus and plant roots. More than 80% of vascular plants contain such fungi on their roots. The fungus absorbs and concentrates nitrogen, phosphate and other ions for the plant’s use The plant supplies the fungus with sugar from photosynthesis The micorrhizae appear as nodules on the plant’s roots

Lichens A lichen is actually two organisms living together: a fungus and an algae (or cyanobacteria) Both benefit Algae makes food for fungus. Fungus improves living conditions for algae by secreting acids that begin to break rock into soil. Live on rocks, soil, branches or tree trunks. Considered a pioneer species