1. BIOLOGY CONCEPTS & CONNECTIONS Fourth Edition Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Neil A. Campbell Jane B. Reece Lawrence G. Mitchell Martha R. Taylor From PowerPoint ® Lectures for Biology: Concepts & Connections CHAPTER 16 The Origin and Evolution of Microbial Life: Prokaryotes and Protists Modules 16.7 – 16.12

2. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Prokaryotes are the oldest life-forms. They lack a nucleus and membrane bound organelles. –They remain the most numerous and widespread organisms on Earth today –Some live in environments that are similar to the conditions on early earth. They include oxygen free depths of the Black Sea, boiling waters of hot springs, and deep sea vents. –Today there are two Divisions of prokaryotes, Archea and Bacteria. Prokaryotes have inhabited Earth for at least 3.5 billion years PROKARYOTES…The first true cells… Figure 16.7

3. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Sheltered from evolutionary alteration, the Archea are relics of the first stages of life on earth. The first to be studied were the methanogens, who are only able to grow in the absence of oxygen. They convert CO2 and H2 into methane gas(CH4). Some live in salty environments like the Dead Sea (halophiles) and others live in deep sea vents and are extreme thermophiles (185F and 245x pressure at sea level). Their DNA holds genes which are unlike any known to molecular biologists. Utilizing a molecular clock, it is hypothesized that the second group of prokaryotes, Bacteria, diverged from Archea approximately 3.5 billion years ago. Archaea—the extremophiles

4. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Bacteria and Archaea Table 16.8

5. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Spheres (cocci) are the most common Rods (bacilli) 16.9 All Prokaryotes come in a variety of shapes Figure 16.9A-C Curves or spirals

6. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings These E. Coli colonies are growing with only glucose as an organic nutrient 16.10 Prokaryotes obtain nourishment in a variety of ways Figure 16.10

7. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Autotrophs obtain carbon from CO 2 and are of two types –Photoautotrophs and chemoautotrophs Heterotrophs obtain carbon from organic compounds –Photo- heterotrophs and chemo- heterotrophs Table 16.10

8. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The first cells were most likely chemoautotrophs –They may have gotten their energy from sulfur and iron compounds

9. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Archaea live in –anaerobic swamps –salt lakes –acidic hot springs –deep-sea hydrothermal vents –animal digestive systems 16.11 Archaea thrive in extreme environments— and in the ocean Figure 16.11A, B

10. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Rotating flagella aid in locomotion 16.12 Diverse structural features help prokaryotes thrive almost everywhere Figure 16.12A Flagellum Plasma membrane Cell wall Rotary movements of each flagellum

11. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Pili help cells cling to surfaces Figure 16.12B Pili

12. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Endospores allow certain bacteria to survive environmental extremes in a resting stage Figure 16.12C Endospore

13. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Many prokaryotes grow in linear filaments Figure 16.12D