1. 1 Chap 28 The Origins of Eukaryotic Diversity Introductory Study Comments 1.Use any first year biology notes you may have because the amount of detail can really bog a student down. 2.Use your review book for learning the major features of most of the organisms. You are not expected to know all of the characteristics but hopefully through these notes, the online chapter outlines and the lab you will get what you need. This protist is a foraminifera; marine, porous, shell of calcium carbonate, with strands of pseudopodia extending through the pores, they can exist in a symbiotic relationship with photosynthetic algae.

2. 2 Intro to Protists Systematists have split protists into many kingdoms Protists are classified in the Domain, Eukarya, but the kingdom differentiations are constantly under construction. It’s a mess. Compare and Contrast the Diversity of Protists 1.Nutrition Aerobic metabolism for the most part Some are photoautotrophs and contain chloroplasts Some are heterotrophs and ingest organic molecules Some, like Euglena, can do both.

3. 3 Figure 28.3 Euglena: an example of a single–celled protist

4. 4 1.Nutrition (cont’d) Their nutritional diversity helps to classify them into: Protozoa: must ingest their food Algae: more plant-like and are photosynthetic 2.Motility Move by flagella or cilia Structure of prokaryotic flagella and eukaryotic flagella differs therefore they are not homologous structures but they are analogous. Prok: flagella at cell surface Euk: flagella have microtubules that are extending from the cytoplasm into the flagellum. Cilia and flagella have a 9+2 arrangement of the microtubules

5. 5 Figure 28.0x A ciliated protozoan

6. 6 Figure 28.1a Too diverse for one kingdom: Amoeba proteus, a unicellular "protozoan"

7. 7 3.Life Cycles Highly varied Mitosis occurs Sexual and asexual reproduction Dominate stage is haploid (growing and feeding) Many can form cysts It’s the cysts forms that are fossilized

8. 8 4.Habitats Many are aquatic: marine or freshwater, ponds, just about any damp area. Protists make up a group of organisms called plankton. Phytoplankton: eukaryotic algae and prokaryotic cyanobacteria Many inhabit the blood or tissues of hosts

9. 9 Origin and Early Diversification of Eukaryotes Endomembrane Systems Added the ability to compartmentalize metabolic activities Examples: nuclear membrane, ER, lysosomes, Golgi apparatus Evolved from infoldings of the prokaryotic plasma membrane. Some of the endomembrane systems are thought to be due to an early symbiotic relationship with other prokaryotes that later became organelles-mitochondria and chloroplasts

10. 10 Evolution of Mitochondria and Plastids (chloroplasts) Endosymbiont Theory or Serial Endosymbiosis by Lynn Margulis Basic idea: mit. and chlor. were once prokaryotes that were engulfed by larger prokaryotes, lived together symbiotically for many years and eventually evolved into organelles within these prokaryotic cells. So the aerobic prokaryotes that were engulfed gave the host cell the ability to live in an increasingly aerobic world The photosynthetic prokaryotes that were engulfed the host cell the ability to photosynthesize.

11. 11 Figure 28.4 A model of the origin of eukaryotes

12. 12 Evidence for serial endosymbiosis 1.Similarity of bacteria and mitochondria and chloroplasts. Similar in size Enzymes on the inner membrane of the organelles resemble those on the plasma membrane of modern prokaryotes. Mit. and chloro. replicate by binary fission Both organelles have a single piece of circular DNA No histones in the organelles Both organelles have tRNA and ribosomes for translation.

13. 13 The eukaryotic cell is a chimera of prokaryotic ancestors Ancestors of Mitochondria and Chloroplasts What did they use to compare the organelles to organisms? the nucleotide sequence of a small ribosomal called SSU- rRNA. this sequence is similar to the sequence in cyanobacteria. Do you see why you should know something about cyanobacteria? also cyanobacteria can split water during PS like the chloroplasts can.

14. 14 Figure 28.5 Secondary endosymbiosis and the origin of algal diversity

15. 15 Gene Transfer to the Nucleus M & C rely on proteins coded by the cell’s genome as well as make proteins themselves. Some of the proteins within the M & C are mixtures (chimeras) of polypeptides from the organelle and the cytoplasm. (ATP synthase) How did some of the organelle’s DNA get to the host genome? a fair assumption is that when the engulfed prokaryote was taken into the host cell, some of its genome was transferred.

16. 16 Secondary endosymbiosis increased the diversity of algae Research on the Three Domains Archaea are more closely related to eukaryotes than prokaryotes Therefore, the host cell that eventually became a eukaryote was derived from an early archaean. Genomes of bacteria are similar to what is in our M & C because of the endosymbiosis. But there are plenty of other bacterial gene sequences that we share so not only do we have figure 28.6 showing the connection of plastids and mitochondria but also other horizontal gene transfers from bacteria to eukaryotes. So one could argue there is NOT ONE COMMON ANCESTOR

17. 17 Figure 28.6 Traditional hypothesis for how the three domains of life are related

18. 18 Figure 28.7 An alternative hypothesis for how the three domains of life are related

19. 19 The Origin of Eukaryotes Catalyzed a Second Wave of Diversification Second Wave? The first wave of diversity was all the prokaryotes that evolved with great metabolic differences. Structural changes were the second wave producing lots of diversity amongst the eukaryotes. Single cell algae, to brown kelp, plants, fungi, animals. One unique characteristic of eukaryotes is their cytoskeleton. The proteins comprising this helped to relate eukaryotes.

20. 20 A Sample of Protistan Diversity Now, try to stay calm as you go through all this. Try to get the key notes about various groups. Where’s that review book? Stay with the major groupings. Diplomnoadid and Parabasala these lack mitochondria but have mitochcondrial genes so it is thought they lost their mitochondria Giardia may be familiar to you. It is an infection you can get from drinking mountain stream water. I’ve heard it described as a “bacterial infection” but it is not a bacteria so we could say it is a disease caused by a protist. Giardia exists as cysts until it gets into your abdominal cavity. Boiling mountain water kills the cysts so this is why you boil water when camping. Me, I just stay in the hotels.

21. 21 Figure 28.9 Giardia lamblia, a diplomonad

22. 22 Trichomonas vaginalis, a parabasalid Sample of Protistan Diversity Another protist that can infect the urethra of guys and the vagina of the gals is Trichomonas vaginalis. This occurs if the normal acidity of the vagina is disturbed. I don’t think this is the “yeast” infection that some women refer to as this is not a yeast.

23. 23 Sample of Protistan Diversity Euglenozoa They have flagella for locomotion a polymer of glucose called paramylon as a storage molecule Examples: Euglena Mainly autotrophic but can be mixotrophic or heterotrophic. Kinetoplastids Example: Trypanosoma which causes African sleeping sickness (not malaria)

24. 24 Figure 28.11x Trypanosoma, the kinetoplastid that causes sleeping sickness

25. 25 Sample of Protistan Diversity Alveolata Characterized by small cavities called alveoli whose function is mostly unknown. Dinoflagellates these are not the same as diatoms possess flagella they are a phytoplankton noted for their spinning motion caused by two flagella cause the red tides near coasts. Red color comes from the pigment xanthophyll in the plastids of the dinoflagellates. Toxins within the dinoflagellates kill invertebrates, fish and humans. some are bioluminescent which can be seen at night when snorkeling. Agitation in the water identifies the dinoflagellates for their predators (fish)

26. 26 Figure 28.12x2 Swimming with bioluminescent dinoflagellates

27. 27 Sample of Protistan Diversity Apicomplexa Parasites of many animals, including us (Plasmodium) Plasmodium causes malaria: Fig. 28.13 Vaccine is difficult as the protist changes its surface proteins that the immune system would react to.

28. 28 Figure 28.13 The two-host life history of Plasmodium, the apicomplexan that causes malaria

29. 29 Sample of Protistan Diversity Ciliates or Ciliophora Fresh water inhabitants Sexual and asexual reproduction Cilia can be arranged in rows. Examples: Stentor, Paramecium Unique feature: a macro- and micronucleus Macronucleus: responsible for binary fission, most cellular functions. Micronucleus: responsible for sexual reproduction and the variation that comes with it.

30. 30 Figure 28.14x Ciliates: Stentor (left), Paramecium (right) Cilia are at the end of the cell and help to bring food into the cell’s mouth. Cilia Food Vacuoles Oral Groove Mouth

31. 31 Sample of Protistan Diversity Stramenopila Contains both heterotrophs and photosynthetic algae Oomycota or Water Molds Heterotrophic decomposers. Have cell walls of cellulose Possess hyphae which are filaments that extend into their nutrient source; dead insects, fish, or other animals. This is analogous to the hyphae of fungi but they are not closely related to fungi (fungi have chitin in their cell walls). Example of convergent evolution Sexual reproduction Another oomycota called Downy Mildew is a plant pathogen that can destroy vineyards. Another oomycote caused potato blight and Irish famine (19 th cent)

32. 32 Figure 28.16 The life cycle of a water mold (Layer 3)

33. 33 Sample of Protistan Diversity Diatoms or Bacillariophyta Yellow or brown Possess silica (glass-like) in cell walls Both fresh and marine organisms Forms diatomaceous earth which can be used for filters Golden Algae or Chrysophyta Color due to carotene and xanthophylls biflagellated Fresh and marine organisms

34. 34 Figure 28.17 Diatoms: Diatom diversity (left), Pinnularia (left)

35. 35 Figure 28.18 A golden alga