Exploring Algae: Diverse Photosynthetic Protists

1. Ch. 19: Protists & Fungi

2. Ch. 19: Protists • Crash Course Biology: • Archaea, Bacteria, Protists

3. Ch. 19: Protists

4. Major Concepts • Protists make up a diverse “catch-all” kingdom of organisms. • Algae are photosynthetic protists that are major producers in the biosphere. • Protozoa are heterotrophic protists that are single celled and motile. • Slime molds are multicellular heterotrophic protists. • Fungi make up a kingdom of multicellular heterotrophic organisms that absorb nutrients from their environment. • Fungi are major decomposers in the biosphere. • Lichens are symbiotic organisms made up of an alga and a fungus.

5. Algae Are Photosynthetic Protists • Algae (plant-like protists): • Green algae: phylum Chlorophyta • Diatoms (Golden algae): phylum Bacillariophyta • Brown algae: phylum Phaeophyta • Red algae: phylum Rhodophyta

6. Phylum Chlorophyta

7. Phylum Bacillariophyta

8. Phylum Phaeophyta

9. Phylum Rhodophyta

10. Algae • Aquatic: droplets of water, air, tree trunks and branches, bottoms of streams, soil, seaside rocks. • Unicellular, colonial, or multicellular (see Fig. 19.9, p. 581). • Multicellular spp. may form long filaments or thin plates of similar cells, or plant-like structures with division of labor. • All are photosynthetic, but not all are green. • The variety of pigments used by different groups of algae suggest evolution in symbiosis with different photosynthetic prokaryotes. • Unicellular and colonial: float near surface of water bodies. • Multicellular: live along shores in shallow water. • Nutrients abundant; living conditions difficult due to periodic drying and variations in temp., light and other factors.

11. Algae • Algae: not a formal biological classification any more due to differences in . . . • Biochemistry, • Cell wall constituents, • Food storage molecules, • Photosynthetic pigments

12. Green Algae May Have Been the Ancestors of Plants Green algae: phylumChlorophyta • Many are unicellular and microscopic; some form large visible floating mats. • Some marine spp. form large, multicellular seaweeds. • Reproduction: Asexual and sexual (see Fig. 19.15, p. 585). • May produce flagellated gametes that appear identical. • Others may produce flagellated sperm and larger, nonmotile ova that are retained in the parent. (Motile: capable of independent movement.) • Many exhibit complex life cycles similar to those in plants, producing both spores and gametes.

13. Green Algae May Have Been the Ancestors of Plants • Biologists believe that plants originated from green algae: • Green algae (but not other algae) contain the same photosynthetic pigments as plants. • Green algae reserve food as starch, as do plants. • Like plants, green algae have cellulose in their cell walls. • Some spp. of green algae have evolved true multicellularity. • Other spp. are intermediate between unicellularity and multicellularity. • Many spp. of green algae have reproductive patterns and life cycles similar to those of plants.

14. Green Algae (Chlorophyta)

15. Homework Assignment • Draw life cycle ofChlamydomonas(Fig. 19.15, p. 585) • Alternating generations: • Asexual reproduction: • Parent cell absorbs flagella; undergoes mitosis. • Up to eight (8) daughter cells (zoospores) are produced. • Zoospores mature into haploid adults (1n).

16. Homework Assignment • Draw life cycle ofChlamydomonas(Fig. 19.15, p. 585) • Sexual reproduction: • Triggered by stress • Mitosis  gametes (+ & -) • Gametes fuse  zygote (2n) • Zygote  zygospore (survive poor conditions) • Zygospore undergoes meiosis  four (4) haploid cells  adults

17. Diatoms Are Important Producers Diatoms: phylum Bacillariophyta • Some of the most intricately patterned creatures on earth (Fig. 19.12, p. 583). • Cell wall formed of double shell of silica (glass). • Two halves (valves) fit together like a box. • Pores in shell which connect interior of cell with external environment form delicate patterns. • Unicellular and microscopic. • Occur as individual cells, filaments, or colonies. • Some move by gliding. • Found in fresh and marine waters.

18. Diatoms Are Important Producers • Photosynthetic (very efficient) Principal producers in many food webs. • Provide much of world’s oxygen. • Also grow in damp habitats, e.g. flower pots. • Various yellow accessory pigments mask their chlorophyll. • Store food as oil.

19. Diatoms Are Important Producers • Reproduction: asexually by cell division; sexually by producing gametes. • Diatoms date back to Cretaceous Period (144 MYA). • Shells have accumulated in certain soils which are now mined as diatomaceous earth. • Used as filter for swimming pools and beer. • Used as silver polish. • Used as paint brightener for marking highways.

20. Diatoms

21. Brown and Red Algae Are Multicellular Brown algae: phylum Phaeophyta • Occupy rocky shores in cooler regions; form extensive offshore beds, e.g. kelp forests of Monterey Bay. • Primary producers for many nearshore marine communities. • Contain cellulose in cell walls. • Store food as a unique carbohydrate or oil; not as starch. • Other pigments mask the chlorophyll. • May be very large, e.g. 100 m tall

22. Brown and Red Algae Are Multicellular • Some are undifferentiated; others have distinct structures: • Holdfast: for anchorage to substrate • Stipe: support • Gas bladder: buoyancy • Blade: photosynthesis • Some have conducting cells similar to phloem (sugar-conducting cells) of plants.

23. Structure of Brown Algae (Kelp) (Thallus)

24. Brown and Red Algae Are Multicellular Red algae: phylum Rhodophyta • Generally grow attached to rocks or other algae. • Absorb blue light, which penetrates deeper into water than other wavelengths of light. • Thus, can grow at greater depths in ocean than any other algae • Possible the chloroplasts of red algae evolved from cyanobacteria due to similar unique pigments. • Cell walls: inner layer of cellulose; outer layer of carbohydrates, e.g. agar • Used for culturing bacteria in lab.

25. Brown and Red Algae Are Multicellular • Both red and brown algae form part of human diet and cosmetics in many parts of world. • Do not contain many kcals, but have a few vitamins and trace elements necessary for human health. • Also produce many compounds used in manufacture of food and other products that require smooth surface, e.g. marshmallows, ice cream, some cheeses, hand lotion, lipstick and paint.

26. Algal Products

27. Protozoa: Animal-like Protists Protists 19.3 Algae (plant-like protists) 19.2 Protozoa (animal-like protists) 1. Flagellates a. Euglenoids b. Dinoflagellates c. Symbiotic Flagellates 2. Sarcodinians/Sarcodines a. Amoeba b. Radiolarians (silica shell) c. Foraminifera (calcium carbonate shell) 3. Sporozoans (phylum Apicomplexa) 4. Ciliates (phylum Ciliophora) 19.4 Slime molds (fungus-like protists)

28. Protozoa: Animal-like Protists • Protozoa: • Mostly heterotrophic and unicellular; some autotrophic

29. Flagellates May Be Consumers or Producers Flagellates : • Comprise several phyla, incl. phylum Zoomastigophora • Unicellular organisms that move by means of flagella. • Some have only one flagellum; others thousands. • Found in damp soil, fresh water and ocean water. • Most reproduce asexually by dividing in two; a few sexually by fusion of identical-appearing gametes.

30. Flagellates May Be Consumers or Producers • Some contain chlorophyll; synthesize food when light is present. • Others capture smaller microorganisms and digest them internally. • Some can switch roles as consumer or producer depending on conditions.

31. Flagellates Euglenoids: small group of flagellates which includes genus Euglena. • Fresh water. • Many contain chloroplasts; manufacture their own food. • Nonphotosynthetic spp. absorb dissolved organic substances or ingest living prey. • Most have a light sensitive eyespot (stigma) and orient toward light. • Lack cell walls, but have protein strips in cell membranes for support.

32. Flagellates

33. Dinoflagellates Dinoflagellates: phylum Dinoflagellata • Single-celled • Mostly marine • Two flagella: • One for propulsion • One for steering • Some are bioluminescent • Some produce toxins and are responsible for “red tides,” (actually harmful algal blooms, HAB’s)

34. Flagellates Dinoflagellates: • Marine flagellates with stiff, armored cellulose walls. • Two flagella, causes cell to spin as it moves through water. • Many dinoflagellates are red. • Some produce a toxin that affects human nervous system. • In great numbers, these cause “red tides.” • In such cases, the toxins may become concentrated (biomagnification): • Clams eat dinoflagellates; human eat clams.

35. Flagellates

36. Flagellates Symbiotic flagellates: live in symbiosis with other organisms, e.g. • Trypanosoma gambiense: causes African sleeping sickness in humans. • Symbiotic flagellates living in gut of termites. • Digest cellulose for termite. • Termite supplies protective environment and steady supply of wood dust.

37. Many Sarcodines Use Pseudopods Sarcodinians (phylum Sarcodina): • Amoebas and relatives: • Thought to have evolved from flagellates, as many develop flagella during some stage of life cycle. • Reproduce asexually by cell division. • Some live in ponds, puddles, damp soil. • Others establish symbiotic relationships that may be parasitic, e.g. the one that causes amoebic dysentery.

38. Sarcodines • Sarcodines ooze or float about more slowly than flagellates. Movement is in direction of longest pseudopod (“false foot”), a fingerlike extension of cytoplasm (see Fig. 19.5, p. 578). • Feed by means of engulfing prey (bacteria, protists, algae) with pseudopod.

39. Sarcodines Radiolarians: shell-bearing marine sarcodine. • Silica shell, or test. • Many long, stiff pseudopodia extend through and radiate from a radiolarian’s shell, giving it a pincushion-like appearance.

40. Sarcodines

41. Sarcodines Foraminifera: shell-bearing marine sarcodine (Fig. 19.6, p. 578). • Calcium carbonate shell. • Great numbers of foraminiferan shells have accumulated over millions of years, forming chalky deposits, e.g. White cliffs of Dover.

42. Sporozoans Are All Parasites of Animals Sporozoans: (phylum Apicomplexa): • Spore-forming protozoa. • Parasites of animals, e.g. Plasmodium vivax, which causes malaria (Fig. 19.8, p. 580). • No means of self-propulsion. • Complex life cycles, involving more than one host.

43. Sporozoans

44. Sporozoans Are All Parasites of Animals • Plasmodium life cycle: • In mosquito: Zygotes divide rapidly, forming large numbers of spores (sporozoites) via meiosis. • Sporozoites are injected into human from mosquito saliva during bite. • In human: Sporozoites reproduce asexually in liver  merozoites. • Merozoites enter bloodstream; invade RBC’s; reproduce asexually  fever/chills in human • Merozoites mature into male and female gametes, which are released into bloodstream. • Mosquito bites infected human & gametes reach her gut, where they mature, fuse,  zygotes

45. Sporozoans

46. Sporozoans Are All Parasites of Animals • Malaria = principal cause of human death in the world today: • Drugs have been developed to control malaria. • Both sporozoans and mosquitoes have developed resistance to those drugs.

47. Sporozoans Are All Parasites of Animals • Other sporozoan diseases: • African Sleeping Sickness: • Caused by Trypanosoma gambiense in tsetse fly (Africa) • Giardia: • Caused by drinking water contaminated with fecal matter of infected animals; “Hikers beware!”

48. Ciliates Have Two Types of Nuclei Ciliates: phylum Ciliophora • Most specialized and complex of protozoa. • Most are unicellular, free-living organisms, e.g. Paramecium. • Fresh and salt water. • Definite semi-rigid shapes.

49. Paramecium

50. Paramecium