1. © 2015 Pearson Education, Inc. PowerPoint Lectures Campbell Biology: Concepts & Connections, Eighth Edition REECE TAYLOR SIMON DICKEY HOGAN Chapter 16 Lecture by Edward J. Zalisko Microbial Life: Prokaryotes and Protists

2. © 2015 Pearson Education, Inc. The Tree of Life

3. © 2015 Pearson Education, Inc. P ROTISTS

4. © 2015 Pearson Education, Inc. 16.12 Protists are an extremely diverse assortment of eukaryotes Protists are an extremely diverse collection of mostly unicellular eukaryotes. Protists phylogeny remains unclear. They are what scientists call organisms that don’t fit any other category: the miscellaneous category. Protists refer to eukaryotes that are not plants, animals, or fungi.

5. © 2015 Pearson Education, Inc. 16.12 Protists are an extremely diverse assortment of eukaryotes Protists obtain their nutrition in many ways. Protists include autotrophs, called algae, producing their food by photosynthesis, heterotrophs, informally called protozoans, eating bacteria and other protists, heterotrophs, called parasites, deriving their nutrition from a living host, which is harmed by the interaction, and mixotrophs, using photosynthesis and heterotrophy.

6. © 2015 Pearson Education, Inc. Figure 16.12a-0 Autotrophy Heterotrophy Mixotrophy Caulerpa, a green algaGiardia, a parasiteEuglena

7. © 2015 Pearson Education, Inc. 16.12 Protists are an extremely diverse assortment of eukaryotes Protists are found in many habitats, including anywhere there is moisture and the bodies of host organisms.

8. © 2015 Pearson Education, Inc. Figure 16.12b-0 A protist from a termite gut covered by thousands of flagella, viewed with scanning electron microscope (left) and light microscope (below)

9. © 2015 Pearson Education, Inc. 16.13 EVOLUTION CONNECTION: Endosymbiosis of unicellular algae is the key to much of protist diversity The endosymbiont theory explains the origin of mitochondria and chloroplasts. According to this theory, oxygen-using autotrophic prokaryotes called cyanobacteria established residence within other, larger heterotrophic prokaryotes. These endosymbionts evolved into mitochondria, giving rise to heterotrophic eukaryotes.

10. © 2015 Pearson Education, Inc. Figure 16.13-1 12 Cyanobacterium Nucleus Heterotrophic prokaryote Endosymbiosis of autotrophic prokaryote Evolved into chloroplast

11. © 2015 Pearson Education, Inc. Figure 16.13-2 Green alga 123 Cyanobacterium Nucleus Heterotrophic prokaryote Endosymbiosis of autotrophic prokaryote Evolved into chloroplast Chloroplast Red alga Autotrophic eukaryotes Prokaryotes became eukaryotes. Shown here is the creation of a chloroplast. Endosymbiosis is also the explanation for or origin of the mitochondria.

12. © 2015 Pearson Education, Inc. 16.13 EVOLUTION CONNECTION: Endosymbiosis of unicellular algae is the key to much of protist diversity In secondary endosymbiosis, an autotrophic eukaryotic protist became endosymbiotic in a heterotrophic eukaryotic protist. 4.Green algae and red algae became endosymbionts following ingestion by different heterotrophic eukaryotes. The heterotrophic host cells enclosed the algal cells in food vacuoles. 5.But the algae—or parts of them—survived and became cellular organelles.

13. © 2015 Pearson Education, Inc. Figure 16.13-4 Green alga 12345 Cyanobacterium Nucleus Heterotrophic prokaryote Endosymbiosis of autotrophic prokaryote Evolved into chloroplast Chloroplast Red alga Autotrophic eukaryotes Heterotrophic eukaryotes Endosymbiosis of autotrophic eukaryote Remnant of green alga Euglena

14. © 2015 Pearson Education, Inc. 16.12 Protists are an extremely diverse assortment of eukaryotes One hypothesis, used here, proposes four monophyletic supergroups. 1.“SAR” (includes Stramenopila, Alveolata, and Rhizaria), 2.Excavata, 3.Unikonta, and 4.Archaeplastida.

15. © 2015 Pearson Education, Inc. 16.14 The “SAR” supergroup represents the range of protist diversity The SAR supergroup forms a huge and extremely diverse group, and stands for three clades: 1. Stramenopila, Include diatoms (glass), brown algae, and water molds. 2. Alveolata, Include dinoflagellates and ciliates (like Paramecium). 3. Rhizaria. Include Amoebas, Foraminiferans and Radiolarians Each clade is a monophyletic group of species that includes an ancestral species and all of its descendants.

16. © 2015 Pearson Education, Inc. 16.15 CONNECTION: Can algae provide a renewable source of energy? Fossil fuels are the organic remains of organisms that lived hundreds of millions of years ago. Diatoms are thought to be the main source of oil. Coal was formed from primitive plants.

17. © 2015 Pearson Education, Inc. 16.14 The “SAR” supergroup represents the range of protist diversity Alveolates (dinoflagellates) are responsible for Blooms—population that sometimes cause warm coastal waters to turn pinkish orange, a phenomenon known as “red tide.”

18. © 2015 Pearson Education, Inc. 16.14 The “SAR” supergroup represents the range of protist diversity Radiolarians are mostly marine and produce a mineralized internal skeleton made of silica.

19. © 2015 Pearson Education, Inc. 16.15 CONNECTION: Can algae provide a renewable source of energy? Lipid droplets in diatoms and other algae may serve as a renewable source of energy. If unicellular algae could be grown on a large scale, this oil could be harvested and processed into biodiesel. Numerous technical hurdles remain before industrial-scale production of biofuel from algae becomes a reality.

20. © 2015 Pearson Education, Inc. Figure 16.15

21. © 2015 Pearson Education, Inc. 16.12 Protists are an extremely diverse assortment of eukaryotes One hypothesis, used here, proposes four monophyletic supergroups. 1.“SAR” (includes Stramenopila, Alveolata, and Rhizaria), 2.Excavata, 3.Unikonta, and 4.Archaeplastida.

22. © 2015 Pearson Education, Inc. 16.16 Some excavates have modified mitochondria Excavata has recently been proposed as a clade on the basis of molecular and morphological similarities. The name refers to an “excavated” feeding groove possessed by some members of the group. Excavates include Many varied organisms such as…

23. © 2015 Pearson Education, Inc. 16.16 Some excavates have modified mitochondria Excavates include, but are not limited to heterotrophic termite endosymbionts (pics next slide), autotrophic species, mixotrophs such as Euglena, the common waterborne parasite Giardia intestinalis, the parasite Trichomonas vaginalis, which causes 5 million new infections each year of human reproductive tracts, and the parasite Trypanosoma, which causes sleeping sickness in humans.

24. © 2015 Pearson Education, Inc. Figure 16.12a-3 termite endosymbionts Euglena Giardia intestinalis Trichomonas vaginalis (causes UTI)Trypanosoma (causes sleeping sickness)

25. © 2015 Pearson Education, Inc. 16.12 Protists are an extremely diverse assortment of eukaryotes One hypothesis, used here, proposes four monophyletic supergroups. 1.“SAR” (includes Stramenopila, Alveolata, and Rhizaria), 2.Excavata, 3.Unikonta, and 4.Archaeplastida.

26. © 2015 Pearson Education, Inc. 16.17 Unikonts include protists that are closely related to fungi and animals Unikonta is a controversial grouping joining amoebozoans (different from ameobas) and a group that includes animals and fungi, addressed at the end of this unit.

27. © 2015 Pearson Education, Inc. 16.17 Unikonts include protists that are closely related to fungi and animals Amoebozoans have lobe-shaped pseudopodia and include many species of free-living amoebas, some parasitic amoebas, and slime molds (Mrs. S’s tree). An amoeba beginning to ingest an algal cell

28. © 2015 Pearson Education, Inc. 16.17 Unikonts include protists that are closely related to fungi and animals Plasmodial slime molds are common where there is moist, decaying organic matter and consist of a single, multinucleate mass of cytoplasm undivided by plasma membranes, called a plasmodium.

29. © 2015 Pearson Education, Inc. Figure 16.17b-0

30. © 2015 Pearson Education, Inc. 16.17 Unikonts include protists that are closely related to fungi and animals Cellular slime molds are common on rotting logs and decaying organic matter and usually exist as solitary amoeboid cells, but when food is scarce, amoeboid cells swarm together, forming a slug-like aggregate that wanders around for a short time, and then form a stock supporting an asexual reproductive structure that produces spores.

31. © 2015 Pearson Education, Inc. Figure 16.17c

32. © 2015 Pearson Education, Inc. 16.12 Protists are an extremely diverse assortment of eukaryotes One hypothesis, used here, proposes four monophyletic supergroups. 1.“SAR” (includes Stramenopila, Alveolata, and Rhizaria), 2.Excavata, 3.Unikonta, and 4.Archaeplastida.

33. © 2015 Pearson Education, Inc. 16.18 Archaeplastids include red algae, green algae, and land plants Almost all the members of the supergroup Archaeplastida are autotrophic. Archaeplastids include red algae, green algae, and land plants.

34. © 2015 Pearson Education, Inc. 16.18 Archaeplastids include red algae, green algae, and land plants Red algae are mostly multicellular, contribute to the structure of coral reefs, and are commercially valuable.

35. © 2015 Pearson Education, Inc. 16.18 Archaeplastids include red algae, green algae, and land plants Green algae may be unicellular, colonial, or multicellular. Volvox is a colonial green algae. https://www.youtube.com/watch?v=9pjW1cMfTz8 https://www.youtube.com/watch?v=9pjW1cMfTz8 Chlamydomonas is a unicellular alga propelled by two flagella.

36. © 2015 Pearson Education, Inc. 16.18 Archaeplastids include red algae, green algae, and land plants Ulva, or sea lettuce, is a multicellular green alga with a complex reproductive life cycle that includes an alternation of generations that consists of a multicellular diploid (2n) form, the sporophyte, that alternates with a multicellular haploid (1n) form, the gametophyte.

37. © 2015 Pearson Education, Inc. 16.19 EVOLUTION CONNECTION: Multicellularity evolved several times in eukaryotes The origin of the eukaryotic cell led to an evolutionary radiation of new forms of life. Unicellular protists are much more diverse in form than simpler prokaryotes.

38. © 2015 Pearson Education, Inc. 16.19 EVOLUTION CONNECTION: Multicellularity evolved several times in eukaryotes Multicellular organisms (seaweeds, plants, animals, and most fungi) are fundamentally different from unicellular organisms. All of life’s activities occur within a single cell in unicellular organisms. A multicellular organism has various specialized cells that perform different functions and are interdependent.

39. © 2015 Pearson Education, Inc. 16.19 EVOLUTION CONNECTION: Multicellularity evolved several times in eukaryotes Multicellular organisms have evolved from three different lineages: stramenopiles (brown algae), unikonts (fungi and animals), and archaeplastids (red algae and green algae).

40. © 2015 Pearson Education, Inc. Figure 16.19a Red algae Other green algae Charophytes Land plants Amoebozoans Nucleariids Fungi Choanoflagellates Animals Green algae Archaeplastids Unikonts Ancestral eukaryote Key All unicellular Both unicellular and multicellular All multicellular