General Biology 1004 Chapter 15 Lecture Handout, Summer 2005 Dr. Frisby

Transcription

1 Slide 1 CHAPTER 15 The Evolution of Microbial Life PowerPoint Lecture Slides for Essential Biology, Second Edition & Essential Biology with Physiology Presentation prepared by Chris C. Romero Neil Campbell, Jane Reece, and Eric Simon Slide 2 BIOLOGY AND SOCIETY: BIOTERRORISM During the fall of 2001, five Americans died from the disease anthrax in a presumed terrorist attack Figure 15.1 Slide 3 Animals, plants, fungi, and viruses have all served as weapons, but the most frequently employed biowarfare agents have been bacteria History provides many examples of the use of biological agents as weapons The practical difficulties of controlling such weapons and a measure of ethical repugnance led the United States to end its bioweapons program in 1969 and to destroy its products Although not all signatories have honored it, 103 nations have signed the Biological Weapons Convention, pledging never to develop or store biological weapons

2 Slide 4 Not all bacteria are harmful to humans Slide 5 MAJOR EPISODES IN THE HISTORY OF LIFE Earth was born 4.5 billion years ago Slide 6 Prokaryotes Bacteria Archaea Protists Eukaryotes Plants Fungi Animals Cenozoic First humans Mesozoic Extinction of dinosaurs Paleozoic Plants and symbiotic fungi colonize land Oldest animal fossils Origin of multicellular organisms Oldest eukaryotic fossils Accumulation of atmospheric Precambrian oxygen from photosynthetic cyanobacteria Oldest prokaryotic fossils Earth cool enough for crust to solidify Origin of Earth Figure 15.2

3 Slide 7 Resolving the Biogenesis Paradox All life today arises by the reproduction of preexisting life, or biogenesis Slide 8 Most biologists now think it is possible that chemical and physical processes on the early Earth produced simple cells Figure 15.3 Slide 9 A Four-Stage Hypothesis for the Origin of Life According to one hypothetical scenario, the first organisms were products of chemical evolution in four stages

4 Slide 10 Stage 1: Abiotic Synthesis of Organic Monomers Stanley Miller Figure 15.4 Slide 11 Stage 2: Abiotic Synthesis of Polymers Researchers have observed polymerization of organic monomers in various situations Slide 12 Stage 3: Origin of Self-Replicating Molecules Laboratory experiments have shown that short RNA molecules can assemble spontaneously Original gene RNA monomers Formation of short RNA polymers: simple genes Assembly of a complementary RNA chain (pairing rules are G with C and A with U) Complementary chain serves as template for making copy of original gene Figure 15.5

5 Slide 13 Stage 4: Formation of Pre-Cells The properties of life emerge from an interaction of molecules organized into higher levels of order Self-replication of RNA Self -replicating RNA acts as template on which polypeptide forms Polypeptide acts as primitive enzyme that aids RNA replication Polypeptide RNA Membrane Polypeptide Figure 15.6 Slide 14 Laboratory experiments demonstrate that pre-cells could have formed spontaneously from abiotically produced organic compounds Figure 15.7 Slide 15 From Chemical Evolution to Darwinian Evolution Over millions of years

6 Slide 16 Prokaryotes Prokaryotes Figure 15.8 Slide 17 They re Everywhere! Prokaryotes Slide 18 The Two Main Branches of Prokaryotic Evolution: Bacteria and Archaea The majority of prokaryotes are bacteria

7 Slide 19 Some archaea are extremophiles Figure 15.9 Slide 20 Extreme thermophiles Methanogens Slide 21 The Structure, Function, and Reproduction of Prokaryotes Prokaryotic cells

8 Slide 22 Prokaryotes come in several shapes Figure Slide 23 Most prokaryotes are unicellular and very small Slide 24 Some prokaryotes Figure 15.11

9 Slide 25 About half of all prokaryotes are motile, using flagella Plasma membrane Cell wall Figure Rotary movement of each flagellum Slide 26 Some prokaryotes Figure Slide 27 Most prokaryotes can reproduce by binary fission at very high rates if conditions are favorable

10 Slide 28 The Nutritional Diversity of Prokaryotes Prokaryotes exhibit four major modes of nutrition Table 15.1 Slide 29 The Ecological Impact of Prokaryotes Prokaryotes Slide 30 Bacteria That Cause Disease Pathogens Figure 15.14

11 Slide 31 Most pathogenic bacteria Exotoxins Endotoxins Slide 32 The best defenses against bacterial disease are Slide 33 Lyme disease Figure 15.15

12 Slide 34 Prokaryotes and Chemical Recycling Prokaryotes play essential roles In chemical cycles in the environment In the breakdown of organic wastes and dead organisms Slide 35 Prokaryotes and Bioremediation Bioremediation is the use of organisms to remove pollutants from water, air, and soil Slide 36 Rotating spray arm Rock bed coated with aerobic bacteria and fungi Liquid wastes Outflow Figure 15.16

13 Slide 37 Certain bacteria can decompose petroleum and are useful in cleaning up oil spills Figure Slide 38 PROTISTS Protists Slide 39 The Origin of Eukaryotic Cells Eukaryotic cells evolved through the combination of two processes

14 Slide 40 In one process, the eukaryotic cell s endomembrane system evolved from inward folds of the plasma membrane of a prokaryotic cell DNA Plasma membrane Cytoplasm Ancestral prokaryote Endoplasmic reticulum Nuclear envelope Nucleus (a) Cell with nucleus and endomembranesystem Figure 15.18a Slide 41 The second process, endosymbiosis, generated mitochondria and chloroplasts Aerobic heterotrophic prokaryote Photosynthetic prokaryote (Some cells) Chloroplast Mitochondrion (b) Photosynthetic eukaryotic cell Figure 15.18b Slide 42 The Diversity of Protists All protists are eukaryotes

15 Slide 43 Protozoans Protozoans Slide 44 Protozoans include (a) Trypanosomes (flagellates) Figure 15.19a Slide 45 Amoebas, with pseudopodia Dysentery (b) An amoeba ingesting food Forams (c) A foram Figure 15.19b, c

16 Slide 46 Apicomplexans Malaria (d) An apicomplexan: Plasmodium Ciliates, with cilia (e) Paramecium Figure 15.19d, e Slide 47 Slime Molds Slime molds Slide 48 Plasmodial slime molds Figure 15.20

17 Slide 49 Cellular slime molds Slide 50 Sluglike colony Amoeboid cells Reproductive structure Figure Slide 51 Unicellular Algae Algae Are photosynthetic protists Are found in plankton

18 Slide 52 Unicellular algae include Dinoflagellates, components of phytoplankton Diatoms, which have glassy walls that fit like a shoebox Figure 15.22a, b Slide 53 Green algae, unicellular and colonial Figure 15.22c, d Slide 54 Seaweeds Seaweeds

19 Slide 55 The three major groups of seaweeds (b) Red algae (a) Green algae (c) Brown algae Figure Slide 56 EVOLUTION CONNECTION: THE ORIGIN OF MULTICELLULAR LIFE Multicellularorganisms Slide 57 The evolutionary links between unicellular and multicellular organisms were probably colonial protists Unicellular protist 2 1 Colony Locomotorcells Foodsynthesizing cells Gamete Early multicellular organism with specialized, interdependent cells 3 Somatic cells Figure Later organism with gametes and somatic (non-reproductive) cells

20 Chapter 15 Study Objectives 1. Explain how organisms may be used as agents of bioterrorism. 2. Identify the sequence and timing of the major events in the evolution of early cellular life, ending with the movement of the first life onto land. 3. Distinguish between spontaneous generation and biogenesis. 4. Describe the four stages of the hypothesis for the origin of life on Earth. Explain how natural selection would have affected these first pre-cells. 5. Describe the relative abundance of prokaryotes on Earth and the many ways they affect humans and ecosystems. 6. Compare the two groups of prokaryotic cells bacteria and archaea. Describe three specific extreme environments in which members of the group Arcaea are found. 7. Describe the structure, function, and reproduction of prokaryotes. 8. Compare the types of nutritional diversity used by prokaryotes. 9. Describe ways that bacteria both harm and benefit humans and ecosystems. 10. Describe the two processes that explain how eukaryotic cells evolved. 11. Describe and compare the four main protest groups. Explain how these different groups impact our lives. 12. Compare unicellular to multicellular life, and explain the advantages of each system.