1. Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint ® Lecture Slides for Essential Biology, Second Edition & Essential Biology with Physiology Neil Campbell, Jane Reece, and Eric Simon Presentation prepared by Chris C. Romero CHAPTER 4 A Tour of the Cell Figures 4.1 – 4.3

2. Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings If you stacked up 8000 cell membranes, they would be only as thick as a page in this book Every second, your body produces about 2 million red blood cells

3. Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings An electron microscope can visualize objects a million times smaller than the head of a pin The cells of a whale are about the same size as the cells of a mouse

4. Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Antibiotics are one of the great marvels of modern medicine BIOLOGY AND SOCIETY: DRUGS THAT TARGET CELLS –Treatment with these drugs will kill invading bacteria –The drugs dont harm the human cells of the host Figure 4.1

5. Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Cells are the building blocks of all life THE MICROSCOPIC WORLD OF CELLS Cells must be tiny for materials to move in and out of them fast enough to meet the cells metabolic needs

6. Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Organisms are either –Single-celled, such as most bacteria and protists –Multicelled, such as plants, animals, and most fungi

7. Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings The light microscope is used by many scientists Microscopes as Windows to Cells –Light passes through the specimen –Lenses enlarge, or magnify, the image Figure 4.2A (a) Light micrograph (LM) of a white blood cell (stained purple) surrounded by red blood cells

8. Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Magnification –An increase in the specimens apparent size Resolving power –The ability of an optical instrument to show two objects as separate

9. Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Cells were first discovered in 1665 by Robert Hooke The accumulation of scientific evidence led to the cell theory –All living things are composed of cells –All cells form from previously existing cells

10. Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings The electron microscope (EM) uses a beam of electrons –It has a higher resolving power than the light microscope

11. Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings The electron microscope can magnify up to 100,000X –Such power reveals the diverse parts within a cell Figure 4.3 Human height Length of some nerve and muscle cells Frog eggs Chicken egg Plant and animal cells Nucleus Most bacteria Mitochondrion Smallest bacteria Viruses Ribosomes Proteins Lipids Small molecules Atoms Unaided eye Light microscope Electron microscope

12. Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings The scanning electron microscope (SEM) is used to study the detailed architecture of the surface of a cell Figure 4.2B (b) Scanning electron micrograph (SEM) of a white blood cell

13. Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings The transmission electron microscope (TEM) is useful for exploring the internal structure of a cell Figure 4.2C (c) Transmission electron micrograph (TEM) of a white blood cell