Protists and Fungi

1. Protists and Fungi

2. Where do Protists and Fungi belong? tolweb.org 1/28/13

3. What is a Protist? • Any eukaryotic organism that is not a plant, an animal, a fungus or a prokaryote • Eukaryotes that are not members of the kingdoms Plantae, Animalia, or Fungi • Most are unicellular

4. Evolution of Protists • Kingdom Protista “the very first” • The first eukaryotic organisms:1.5 bya • May have evolved from the symbiosis of several cells • Diverse! Scientists think that there should be several kingdoms

5. Classification of Protists • DNA evidence that protists evolved independently from archaebacteria • Because the new classification is not perfected, we will break them down into the traditional groups • These categories are an artificial way to organize diverse groups of organisms

6. ProtistsThe “Junk Drawer” of the Kingdoms • Animal-like • Plant-like • Fungus-like

7. Animal-like Protists (Protozoans) • “First animals:” protozoa • Heterotrophs distinguished from each other by way of movement • Flagella • Zooflagellates • Pseudopods • Amoeba • Foraminifera • Cilia • Paramecium

8. Sporozoans • Do not move on their own • Parasitic • Infect: • worms, fish, birds, humans, etc. • Cause: • Malaria • African Sleeping Sickness • Most have complex life cycles involving more than one host

9. Plant-like Protists: Unicellular Algae • Accessory pigments: many algae have compounds that absorb light at different wavelengths than chlorophyll • Chlorophyll and accessory pigments allow algae to harvest and use the energy from sunlight

10. Plant-like Protists: Unicellular Algae • Euglenophyte • Euglena • Dinoflagellates • Diatoms

11. Aside: What are Plankton? • Any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. • That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification. They provide a crucial source of food to larger, more familiar aquatic organisms such as fish and cetacea • Protists are Plankton…not all Plankton are Protists!!! • From the Greek planktos: “to drift or wander” • Phytoplankton • Small, photosynthetic organisms found near the surface of the ocean • Nearly ½ of photosynthesis on Earth is carried out by phytoplankton • Zooplankton • Holoplankton • Meroplankton

12. Symbiotic Algae • Many types of coral contain intercellular dinoflagellates • Dinoflagellates allow the coral animals to use the food products of photosynthesis • Dinoflagellates can feed on the waste products of coral animals and can use the coral as a home

13. Algal Blooms • Many protists absorb organic material and use it for food • Grow rapidly in regions where sewage is discharged • Recycle the sewage and other waste materials • Blooms: When the amount of waste is excessive, populations grow in enormous masses • The algal blooms deplete the water of nutrients, and the cells die in great numbers • The decomposition of these dead algae can rob the water of its oxygen, choking resident fish and invertebrate life

14. Algal Blooms • Great blooms of the dinoflagellatesGonyaulax and Gymnodinium have occurred in recent years on the east coast of the USA • “Red Tides”: these species produce a potentially dangerous toxin • Filter-feeding shell-fish such as clams can trap Gonyaulax and Gymnodinium for food and become filled with the toxin • Eating shellfish infected with red tide can lead to serious illness, paralysis, and even death

15. Plant-like Protists: Multicellular Red Algae • Phylum Rhodophyta, meaning “red plants” • Able to live at great depths due to their efficiency in harvesting light energy • Found in marine waters from the polar regions to the tropics • Can grow in depths up to 260 m • Most are multicellular, having complex life-cycles • Lack flagella and centrioles

16. Plant-like Protists: Multicellular Brown Algae • Phylum Phaeophyta, meaning “dusky plants” • Largest and most complex of the algae • Multicellular, mainly marine algae • Found in cool, shallow coastal waters of temperate or arctic areas • Giant kelp: the largest known brown alga • Can grow more than 60 meters in length • Sargassum: another huge brown alga that floats in large mats near Bermuda, in “The Sargasso Sea”

17. Plant-like Protists: Multicellular Brown Algae • Fucus: a common brown alga found along the rocky coast of the eastern USA • Each Fucus plant has a holdfast, a structure that attaches the alga to the bottom • Bladders: gas filled swellings that float and keep the algae upright in the water

18. Plant-like Protists: Multicellular Green Algae • Phylum Chlorophyta, meaning “green plants” • Scientists hypothesize that the ancestors of modern land plants looked a lot like certain species of living green algae • Found in fresh and salt water, and even in moist areas on land • Many live as single cells, others form colonies

19. Human Uses of Algae • Algae are a major food source for life in the oceans • Many species of algae are rich in vitamin C and iron • Chemicals in algae are used to treat: • Stomach ulcers • High blood pressure • Arthritis, etc. • Algae used in food production: • Dried Porphyra-used to warp sushi • Ice-cream • Salad dressing • Pudding • Candy bar • Pancake syrup • Eggnog

20. Human Uses of Algae • Algae use in industry: • Plastics • Waxes • Transistors • Deodorants • Paints • Lubricants • Artificial wood • Scientific laboratories: • Agar: thickens nutrient mixtures used to grow bacteria and other microorganisms

21. Fungus-like Protists • Heterotrophs that absorb nutrients from dead or decaying organic matter • Unlike most true fungi, fungus-like protists have centrioles • They lack the chitin cell walls of true fungi • Cellular slime molds • Acellular slime molds • Water molds

22. Slime Molds • Found in places that are damp and rich in organic matter (forest or backyard compost pile) • Play key roles in recycling organic matter • Cellular slime molds • Acellular slime molds

23. Cellular Slime Molds • Spend most of their lives as free-living cells • Not easily distinguishable from soil amoebas • Reproduce rapidly in nutrient-rich soils

24. Acellular Slime Molds • Also begin life as amoeba-like cells • Cells fuse to produce structures with many nuclei

25. Water Molds • Thrive on dead or decaying organic matter in water • Are plant parasites on land • Not true fungi • Hyphae: thin filaments produced by water molds • Have both sexual and asexual phases in the life cycle

26. Ecology of Fungus-like Protists • Important as recyclers of organic material • Help things rot • Some can harm living things • Cause plant diseases • Mildews and blights of grapes and tomatoes

27. Water Molds and the Potato Famine • ~ 40 million Americans can trace some part of their ancestry to Ireland • Potatoes • Native to South America • Introduced to Europe by Spanish explorers • By the 1840s  major food crop of Ireland • Protist: Phytophthorainfestans • An oomycete that produces airborne spores that destroy all parts of the potato plant • Reduces the potato to a spongy sac of spores and dust

28. Water Molds and the Potato Famine • Summer, 1845: unusually wet and cold • 60% of the Irish potato crop was destroyed • > 1 million people starved • 1.5 million people  USA

29. What Are Fungi? • Eukaryotes • Heterotrophs • Chitin: complex carbohydrate found in the cell wall • Also found in the external skeletons of insects

30. What Are Fungi? • External digestion and reabsorption • Many absorb nutrients from decaying matter in the soil • Others are parasites

31. Structure and Function of Fungi • Multicellular • Exception: yeasts are unicellular • Hyphae: tiny filaments that make up fungi • Mycelium: many hyphae tangled together that make up the bodies of multicellular fungi • Suited to absorb food

32. Structure and Function of Fungi • Fruiting Body: Reproductive structure (the mushroom!) • Develops from an underground mycelium • Clusters of mushrooms are often part of the same mycelium… they are a part of the same organism

33. Structure and Function of Fungi • Some mycelia can live for several years • “Fairy Rings”

34. Asexual Reproduction • Cells or hyphae break off from a fungus • Begin to grow on their own • Sporangia: structures in ferns and some fungi that contain spores • Sporangiophores: specialized hyphae where sporangia are found

35. Sexual Reproduction • Involves two different mating types • Gametes are not called male and female • + and -

36. Reproduction in Fungi • Gametangium: gamete-forming structure • Produced when the hyphae of opposing mating types of fungi meet • A diploid nucleus (zygote), is formed  meiosis occurs  produces haploid cells

37. How Fungi Spread • Fungal spores are found in almost every environment • Dry, almost weightless spores that scatter in the wind • Some fungi lure animals to disperse the spores • Stinkhorns smell like rotting meat, which attracts flies

38. Classification of Fungi • Over 100,000 species • Classified according to: • Structure • Method of reproduction

39. Fungi • Primitive fungi • Club fungi • Basidiomycota • Bread mold • Zygomycota • Sac fungi • Ascomycota

40. The Club Fungi (mushrooms) • Phylum Basidiomycota • Named from a specialized reproductive structure that resembles a club • Basidium: spore-bearing structure • Found on the gills that grow on the underside of mushroom caps

41. Life Cycle of Club Fungi • The most elaborate life cycle of all the fungi • In a suitable environment the spore-producing fruiting bodies push above ground as mushrooms

42. Life Cycle of Club Fungi • Fruiting bodies expand at astonishing speed, sometimes producing fully developed mushrooms overnight • Cells enlarge, not divide • When the mushroom cap opens there are gills on the underside

43. Diversity of Club Fungi • In addition to mushrooms, basidiomycetes include shelf fungi, near decaying trees • Other examples of basidiomycetes • Puffballs, earthstars, jelly fungi and plant parasites known as rusts

44. The Common Molds • Phylum Zygomycota • Familiar molds that grow on meat, cheese, and bread • Zygospore: resting spore that contains zygotes formed during the sexual phase of a mold’s life cycle; may remain dormant for months

45. Structure and Function of Molds • Rhizoids: a rootlike hypha that penetrates the surface of an object • Stolons: a stemlike hypha that runs along the surface of an object • Example: black bread mold, Rhizopusstolonifer

46. Life Cycle of Bread Molds

47. The Sac Fungi • Phylum Ascomycota • Ascus: reproductive structure that contains spores • More than 30,000 species; the largest phylum of the kingdom Fungi • Size variation • yeast: microscopic • cup fungi: seen with the naked eye

48. Reproduction Asexual Sexual Haploid hyphae of two different mating types grow close together A diploid zygote forms and divides by meiosis into haploid ascospores • Tiny spores called conidia are formed at the tips of specialized hyphae called conidiophores • Conidia that land in a good environment grow into haploid mycelium

49. Yeasts • Unicellular fungi • Form asci with ascospores during the sexual phase of their life cycle • The ascospores become active in a moist environment

50. Edible and Inedible Mushrooms • Many mushrooms are considered delicacies • When properly cooked and prepared, domestic mushrooms are tasty and nutritious • Wild mushrooms: some are edible, many are poisonous • Don’t eat wild mushrooms!