Chapter 21: Protists

Transcription

1 Chapter 21: Protists Section 1: Characteristics of Protists Gamete: a haploid reproductive cell that unites with another gamete to form a zygote Zygote: the cell that results from the fusion of gametes Zygospore: a thick-walled protective structure that contains a zygote I. Characteristics of Protists A. What Are Protists? Made up of organisms that do not belong in any of the other kingdoms 3.Eukaryotic organisms that cannot be classified as 4. Several important characteristics Membrane-bound organelles 1) 2) Complex cilia and flagella Section 2: Groups of Protists Pseudopodium: a cytoplasmic extension that functions in food ingestion and movment Plasmodium: the multinuclate cytoplasm of a slime mold that is surrounded by a membrane that moves as a mass 1

2 I. Grouping Protists A. By how they obtain nutrients Get energy by photosynthesis ( ) Capture and eat other organisms ( ) 3. Absorb nutrients from their environment ( ) B. Animal-like Protists Called protozoa, means Ingest other organisms to obtain energy Amoeboid Protists (Amoebas) Organisms that move by using extensions of their cells called pseudopodia (singular, pseudopodium) Pseudopodia used to surround and engulf food particles Live in fresh water, salt water, and soil d. e. 6. Cilliates (Paramecium) Covered by hairlike structures called d. Can be found in fresh water and salt water 7. Flagellates (Euglena) Have whip-like structures called Some have one flagellum, others have many Some also have cilia or form pseudopodia d. 2

3 e. 8. Sporozoans Form sporelike cells when they reproduce called Lack flagella, cilia, and pseudopodia d. C. Plantlike Protists 3. Obtain energy through photosynthesis 4. Diatoms Unique double shells 5. Euglenoids Freshwater protists that have one or two flagella Some are both photosynthetic and heterotrophic d. Others lack chloroplasts and ingest their food e. Some have an eyespot, a light-sensitive organ that helps them move toward light 6. Dinoflagellates Unicellular protists that typically have two flagella 3

4 d. Most have protective coats that may contain silica 7. Red Algae Coraline algae play important role in formation of coral reefs 8. Brown Algae Largest are kelp that can reach 60 m (197 ft) in length 9. Green Algae Form a major part of D. Funguslike Protists Slime Molds 3. Water Molds and Downy Mildews Common parasites of aquarium fish 1846, one type of water mold destroyed almost the entire potato crop in Ireland, which led to the Great Famine d. 1879, a downy mildew of grapes almost wiped out the French wine industry Section 3: Protists and Humans Algal Bloom: rapid increase in population of algae in aquatic ecosystem 4

5 I. Protists and Disease A. Have significant effects on humans and other organisms B. C. D. E. Cause a number of human diseases F. Disease caused by an intestinal parasite of the genus Giardia Parasite enters the body as a cyst Move through the intestine d. Cause severe diarrhea & intestinal cramps that may last 2-6 weeks e. Disease is rarely fatal Symptoms of amebic dysentery include Pain Bloody diarrhea Fever Entamoeba histolytica forms cysts that are transmitted in contaminated water 3. Commonly in countries that have poor sanitation. II. Protists and the Environment A. Oxygen Production and Nutrient Cycling Plantlike protists, along with photosynthetic cyanobacteria, produce at least half of Earth s oxygen Plantlike protists also consume carbon dioxide 3. Protists are important decomposers Contribute to the recycling of nutrients, such as 5

6 B. Food Webs Photosynthetic protists, along with cyanobacteria, form the base of almost all aquatic food chains C. Algal Blooms Occur during warm seasons Nutrients in ocean water are abundant Red tide is caused by a bloom of dinoflagellates that produce powerful toxins 5. Humans can become ill if they eat fish or shellfish during a red tide E. Protists and Industry Important in many foods, in industrial and consumer products, and in scientific research Used as thickening agents in foods such as 3. Empty shells of diatoms are used as abrasives in cleaning agents, such as Section 1: Characteristics of Fungi Chapter 22: Fungi Chitin: a carbohydrate found in the cell walls of fungi and other organisms I. What Are Fungi? A. Very diverse group of organisms Three characteristics: 6

7 B. Structure and Function Most of the body of a fungus is hidden in the ground or in the substance that the fungus feeds on Large surface area 3. C. Obtaining Nutrients Release enzymes that break down organic and inorganic matter into nutrients Absorb the nutrients across their cell walls 3. Absorb nutrients from dead organisms are called Recycle nutrients that otherwise would stay trapped in the bodies of dead organisms 4. Absorb nutrients from living hosts are called Section 2: Groups of Fungi Lichen: a fungus in a symbiotic association with a photosynthetic partner Mycorrhiza: a symbiotic association between fungi and plant roots I. II. III. A. Group of aquatic fungi that provide clues about the evolution of fungi A. Named for sexual reproductive structures that produce zygotes inside a tough capsule A. Sac fungi are characterized by an ascus, a saclike sexual reproductive structure that produces spores 7

8 IV. A. Club fungi are characterized by a basidium, a clublike sexual reproductive structure that produces spores B. C. When the fungus reproduces sexually, a ring of mushrooms appears The largest known organism on the planet is a club fungus in Oregon that is 3.5 miles across V. Fungal Partnerships A. Fungi form mutualistic symbiotic associations to form lichens and mycorrhizae B. C. A lichen is an association between a partner, such as a cyanobacterium, a green alga, or both D. A mycorrhiza is an association between Section 3: Fungi and Humans Dermatophyte: a fungus that infects the hair or nails I. Fungi and Industry A. Used for food, medicines, research, alternative fuels, pest control B. Fungi are probably most familiar as food 3. C. Yeast is used in 8

9 D. Also produce the citric acid that is used in soft drinks and candies E. Fungi are an important part of the medical industry Produce the antibiotics Black bread mold produces cortisone, a drug used to treat skin rashes and to reduce joint swelling 3. Yeast cells have been genetically engineered to make a vaccine for hepatitis B F. Can also help us improve our environment and reduce pollution G. Yeast produces gasohol, a fuel alternative to gasoline H. Use of fungal insect parasites to kill crop-destroying insects helps reduce the use of harmful pesticides II. Fungi and Ecosystem A. Play important ecological roles by decomposing organic matter and by breaking down and absorbing minerals from rocks and soil III. Fungi and Disease A. Fungal Infections Can grow on and inside tissues of the body 3. Dermatophytes are fungi that infect the skin and nails These fungi absorb nutrients and release metabolic wastes that irritate the skin B. Yeast is a normal resident of the human body Antibiotics, hormonal changes, or illness can cause yeast to grow too much IV. Fungal Toxins A. Many fungi produce dangerous toxins. B. Toxins in mushrooms can cause 9