Life: the Science of Biology

Lecture Notebook to accompany <ul style="display: flex;"><li style="flex:1">Sinauer aSSociateS, inc. </li><li style="flex:1">MacMillan </li></ul>Copyright © 2014 Sinauer Associates, Inc. Cover photograph © Alex Mustard/naturepl.com. This document may not be modified or distributed (either electronically or on paper) without the permission of the publisher, with the following exception: Individual users may enter their own notes into this document and may print it for their own personal use. The Origin and Diversification of Eukaryotes 0207 27.1 A Hypothetical Sequence for the Evolution of the Eukaryotic Cell (Page 550) Cell wall DNA The protective cell wall was lost. 1Infolding of the 2plasma membrane added surface area without increasing the cell’s volume. Cytoskeleton (microfilament and microtubules) formed. 34Internal membranes studded with ribosomes formed. As regions of the infolded plasma membrane enclosed the cell’s DNA, a precursor of a 5nucleus formed. Microtubules from the cytoskeleton formed the eukaryotic flagellum, enabling propulsion. 6Early digestive vacuoles evolved into lysosomes using enzymes from the early endoplasmic reticulum. 789Mitochondria formed through endosymbiosis with a proteobacterium. Endosymbiosis with cyanobacteria led to the development of chloroplasts. Flagellum To add your own notes to any page, use Adobe Reader’s Typewriter feature, accessible via the Typewriter bar at the top of the window. (Requires Adobe Reader 8 or later. Adobe Reader can be downloaded free of charge from the Adobe website: <a href="/goto?url=http://get.adobe.com/reader" target="_blank">http://get.adobe.com/reade</a><a href="/goto?url=http://get.adobe.com/reader" target="_blank">r</a>.) Chloroplast Mitochondrion Nucleus 2© 2014 Sinauer Associates, Inc. |chapter 27 the origin and Diversification of eukaryotes 3(A) Primary endosymbiosis Eukaryote Cyanobacterium Cyanobacterium outer membrane Peptidoglycan Cyanobacterium inner membrane Host cell nucleus Chloroplast Peptidoglycan has been lost except in glaucophytes. Chloroplastcontaining eukaryotic cell (B) Secondary endosymbiosis Host eukaryotic cell Host membrane (from endocytosis) encloses the engulfed cell. A trace of the engulfed cell’s nucleus is retained in some groups. The engulfed cell’s plasma membrane (white) has been lost in euglenids and dinoflagellates. 27.2 Endosymbiotic Events in the Evolution of Chloroplasts (Page 552) © 2014 Sinauer Associates, Inc. |chapter 27 the origin and Diversification of eukaryotes 4Alveolates Stramenopiles Rhizaria Excavates Plantae Chs. 28 and 29 Amoebozoans Fungi Ch. 30 Ophisthokonts Choanoflagellates Animals Chs. 31–33 Precambrian <ul style="display: flex;"><li style="flex:1">Paleozoic </li><li style="flex:1">Mesozoic </li></ul>Cenozoic to 4.5 bya <ul style="display: flex;"><li style="flex:1">1.5 </li><li style="flex:1">1.4 </li><li style="flex:1">1.3 </li><li style="flex:1">1.2 </li><li style="flex:1">1.1 </li><li style="flex:1">1.0 </li><li style="flex:1">0.9 </li><li style="flex:1">0.8 </li><li style="flex:1">0.7 </li><li style="flex:1">0.6 </li><li style="flex:1">0.5 </li><li style="flex:1">0.4 </li><li style="flex:1">0.3 </li><li style="flex:1">0.2 </li><li style="flex:1">0.1 </li><li style="flex:1">0</li></ul>Billions of years ago 27.3 Precambrian Divergence of Major Eukaryote Groups (Page 553) © 2014 Sinauer Associates, Inc. |chapter 27 the origin and Diversification of eukaryotes 5Dinoflagellates Apicomplexans Ciliates Stramenopiles Rhizaria In-Text Art (Page 553) Peridinium sp. Equatorial groove Longitudinal groove 27.4 A Dinoflagellate (Page 554) © 2014 Sinauer Associates, Inc. |chapter 27 the origin and Diversification of eukaryotes 6<ul style="display: flex;"><li style="flex:1">(A) Paramecium sp. </li><li style="flex:1">(B) Didinium nasutum </li><li style="flex:1">(C) Euplotes sp. </li></ul>10 µm 27.5 Diversity among the Ciliates (Page 554) <ul style="display: flex;"><li style="flex:1">7 µm </li><li style="flex:1">25 µm </li></ul><ul style="display: flex;"><li style="flex:1">Rows of fused cilia </li><li style="flex:1">Oral groove </li></ul><ul style="display: flex;"><li style="flex:1">Cilia </li><li style="flex:1">Bands of cilia </li></ul>The macronucleus controls the cell’s activities. Micronuclei function in genetic recombination. Contractile vacuole Alveoli Cilia Digestive vacuole Oral groove Trichocyst Fibrils Anal pore Pellicle Alveolus Cilium 27.6 Anatomy of Paramecium (Page 555) © 2014 Sinauer Associates, Inc. |chapter 27 the origin and Diversification of eukaryotes 7INVESTIGATINGLIFE 27.7 The Role of Vacuoles in Ciliate Digestion HYPOTHESIS The digestive vacuoles of Paramecium produce an acidic environment that allows the organism to digest food particles. Method 1. Feed Paramecium yeast cells stained with Congo red, a dye that is red at neutral or basic pH but turns green at acidic pH. 2. Under a light microscope, observe the formation and degradation of digestive vacuoles within the Paramecium. Note time and sequence of color (i.e., acid level) changes. Results 1 A digestive vacuole forms around yeast cells. 2 The change in color shows that the interior vacuole has become Stained yeast cells acidic. Oral groove As products of digestion move into the cytosol, the pH increases in the vacuole (the dye becomes red again). 3Red-stained (basic) waste material is expelled. 4CONCLUSION Some ciliates acidify digestive vacuoles to assist in the breakdown of food. Go to BioPortal for discussion and relevant links for all INVESTIGATINGLIFE figures. (Page 555) © 2014 Sinauer Associates, Inc. |chapter 27 the origin and Diversification of eukaryotes 8Alveolates Brown algae Diatoms Oomycetes Rhizaria In-Text Art (Page 555) 25 µm Diatoms display either radial (circular) symmetry... ...or bilateral (left-right) symmetry. 27.8 Diatom Diversity (Page 556) © 2014 Sinauer Associates, Inc. |chapter 27 the origin and Diversification of eukaryotes 9<ul style="display: flex;"><li style="flex:1">(A) Himanthalia elongata </li><li style="flex:1">(B) Postelsia palmiformis </li></ul>Holdfasts 27.9 Brown Algae (Page 556) Saprolegnia sp. 3 mm 27.10 An Oomycete (Page 557) © 2014 Sinauer Associates, Inc. |chapter 27 the origin and Diversification of eukaryotes 10 Alveolates Stramenopiles Cercozoans Foraminiferans Radiolarians In-Text Art (Page 557) 1 mm 27.11 Building Blocks of Limestone (Page 557) <ul style="display: flex;"><li style="flex:1">(A) </li><li style="flex:1">(B) </li></ul><ul style="display: flex;"><li style="flex:1">Astrolithium sp. </li><li style="flex:1">Hexacontium sp. </li></ul>50 µm 250 µm 27.12 Radiolarians Exhibit Distinctive Pseudopods and Radial Symmetry (Page 557) © 2014 Sinauer Associates, Inc. |chapter 27 the origin and Diversification of eukaryotes 11 Excavates Diplomonads Parabasalids Heteroloboseans Euglenids Kinetoplastids In-Text Art (Page 558) (A) Giardia sp. 2.5 µm (B) T r ichomonas vaginalis 2.5 µm 27.13 Some Excavate Groups Lack Mitochondria (Page 558) © 2014 Sinauer Associates, Inc. |chapter 27 the origin and Diversification of eukaryotes 12 Photosynthetic chloroplasts are prominent features in a typical Euglena cell. Flagella Nucleus Pigment shield Stored polysaccharides from photosynthesis Contractile vacuole Photoreceptor 27.14 A Photosynthetic Euglenid (Page 559) TablE27.1 Three Pathogenic Trypanosomes <ul style="display: flex;"><li style="flex:1">Trypanosoma brucei </li><li style="flex:1">Trypanosoma cruzi </li><li style="flex:1">Leishmania major </li></ul>Leishmaniasis Sand fly <ul style="display: flex;"><li style="flex:1">Human disease </li><li style="flex:1">Sleeping sickness </li></ul>Tsetse fly Chagas disease Assassin bugs (many species) None Insect vector Vaccine or effective cure Strategy for survival <ul style="display: flex;"><li style="flex:1">None </li><li style="flex:1">None </li></ul>Changes surface recognition Causes changes in surface recognition Reduces effectiveness of macrophage <ul style="display: flex;"><li style="flex:1">molecules frequently </li><li style="flex:1">molecules on host cell </li><li style="flex:1">hosts </li></ul><ul style="display: flex;"><li style="flex:1">Site in human body </li><li style="flex:1">Bloodstream; in final stages, Enters cells, especially muscle cells </li></ul>attacks nerve tissue Enters cells, primarily macrophages Approximate number of deaths per year <ul style="display: flex;"><li style="flex:1">50,000 </li><li style="flex:1">45,000 </li><li style="flex:1">60,000 </li></ul>(Page 559) © 2014 Sinauer Associates, Inc. |chapter 27 the origin and Diversification of eukaryotes 13 Amoebozoans Loboseans Plasmodial slime molds Cellular slime molds In-Text Art (Page 559) Chaos carolinensis Pseudopods Nebela collaris 120 µm 27.15 An Amoeba in Motion (Page 559) Shell (test) made of sand grains Plasma membrane of amoeba Pseudopods of amoeba 18 µm 27.16 Life in a Glass House (Page 560) © 2014 Sinauer Associates, Inc. |chapter 27 the origin and Diversification of eukaryotes 14 (A) 30 mm (B) 1.5 mm 27.17 A Plasmodial Slime Mold (Page 560) The sporangium of the mature fruiting structure will release spores. Dictyostelium discoideum Fruiting structure (various stages) Slug 0.25 mm 27.18 A Cellular Slime Mold (Page 561) © 2014 Sinauer Associates, Inc. |chapter 27 the origin and Diversification of eukaryotes 15 Macronucleus Micronucleus 1 Two paramecia conjugate; all but one micronucleus in each cell disintegrate. The remaining micronucleus undergoes meiosis. 2 Three of the four haploid micronuclei disintegrate; the remaining micronucleus undergoes mitosis. 3The paramecia donate micronuclei to each other. The macronuclei disintegrate. 4The two micronuclei in each cell—each genetically 5 The new diploid micronuclei divide mitotically, eventually giving rise to a macronucleus and the appropriate number of micronuclei. different—fuse. 27.19 Conjugation in Paramecia (Page 562) © 2014 Sinauer Associates, Inc. |chapter 27 the origin and Diversification of eukaryotes 16 START Eventually, some merozoites develop into male and 8A blood-feeding female mosquito ingests the Plasmodium gametocytes. 1Merozoites also invade red blood cells, grow and divide, and lyse the cells. They can reinfect the liver, producing new generations. 7female gametocytes. Male gamete Within the mosquito, male and female gametocytes develop into gametes, which fuse. 2Red blood cell Female gamete The resulting zygote 3enters the mosquito’s gut wall and forms a cyst. <ul style="display: flex;"><li style="flex:1">Events in human </li><li style="flex:1">Events in mosquito </li></ul>Mosquito's gut wall The zygote gives rise to sporozoites that invade the salivary gland. 4Sporozoites penetrate liver cells and develop into merozoites. 6(B) Human liver cell Mosquito's salivary gland The mosquito injects sporozoites into a human’s blood when it feeds. 5 Cysts 27.20 Life Cycle of the Malarial Parasite (Page 564) Mosquito's gut wall 170 µm © 2014 Sinauer Associates, Inc. |chapter 27 the origin and Diversification of eukaryotes 17 INVESTIGATINGLIFE 27.21 Can Corals Reacquire Dinoflagellate Endosymbionts Lost to Bleaching? HYPOTHESIS Bleached corals can acquire new photosynthetic endosymbionts from their environment. Method 1. Count numbers of Symbiodinium, a photosynthetic dinoflagellate, living symbiotically in samples of a coral (Briareum sp.). 2. Stimulate bleaching by maintaining all Briareum colonies in darkness for 12 weeks. 3. After 12 weeks of darkness, count numbers of Symbiodinium in the coral samples; then return all colonies to light. 4. In some of the bleached colonies (the experimental group), introduce Symbiodinium strain B211—dinoflagellates that contain a unique molecular marker. Do not expose the others (the control group) to strain B211. Maintain both groups in the light for 6 weeks. Results 70 Experimental (exposed to strain B211) 60 Control (not exposed to strain B211) 50 40 30 20 10 Six weeks after return to light, both groups showed increases in number of symbionts present. DNA analysis showed that strain B211 symbionts were present in the experimental group. After 12 weeks in dark, 0–1% of the photosynthetic endosymbionts remained. 3210<ul style="display: flex;"><li style="flex:1">Pre-bleach </li><li style="flex:1">Post-bleach </li><li style="flex:1">Week 3 </li><li style="flex:1">Week 6 </li></ul>(original state) <ul style="display: flex;"><li style="flex:1">Pre-bleach </li><li style="flex:1">Post-bleach </li></ul>CONCLUSION Corals can acquire new endosymbionts from their environment following bleaching. Go to BioPortal for discussion and relevant links for all INVESTIGATINGLIFE figures. (Page 565) © 2014 Sinauer Associates, Inc.

Life: the Science of Biology

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