1. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Lectures by Chris C. Romero PowerPoint ® Lectures for Essential Biology, Third Edition – Neil Campbell, Jane Reece, and Eric Simon Essential Biology with Physiology, Second Edition – Neil Campbell, Jane Reece, and Eric Simon CHAPTER 4 A Tour of the Cell

6. Biology and Society: Cells That Cure During a heart attack, –Heart muscle cells die because they are starved for oxygen. Unfortunately, these kinds of cells do not regenerate. Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings

7. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings In recent years, a new treatment called “cell therapy” has emerged. In this procedure, cells are taken from other parts of the body –And delivered to the ailing heart, facilitating healing.

8. Figure 4.1

9. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Microscopic World of Cells Organisms are either: –Single-celled, such as most bacteria and protists –Multicelled, such as plants, animals, and most fungi

10. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Microscopes as a Window on the World of Cells The light microscope is used by many scientists. –Light passes through the specimen. –Lenses enlarge, or magnify, the image. Euglena

11. Figure 4.2a

12. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Magnification –Is an increase in the specimen’s apparent size. Resolving power –Is the ability of an optical instrument to show two objects as being separate.

13. Copyright © 2007 Pearson Education Inc., publishing as Pearson 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 are formed from previously existing cells.

14. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The electron microscope (EM) uses a beam of electrons. –It has a higher resolving power than the light microscope. The electron microscope can magnify up to 100,000X. –Such power reveals the diverse parts within a cell.

15. Figure 4.3

16. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The scanning electron microscope (SEM) is used to study the detailed architecture of the surface of a cell.

17. Figure 4.2b

18. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The transmission electron microscope (TEM) is useful for exploring the internal structure of a cell.

19. Figure 4.2c

20. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Two Major Categories of Cells The countless cells on earth fall into two categories: –Prokaryotic cells –Eukaryotic cells Prokaryotic and eukaryotic cells differ in several respects.

21. Figure 4.4

22. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Prokaryotic cells –Are smaller than eukaryotic cells. –Lack internal structures surrounded by membranes. –Lack a nucleus.

23. Figure 4.5

24. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings A Panoramic View of Eukaryotic Cells An idealized animal cell Cytoplasmic Streaming

25. Figure 4.6a

26. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings An idealized plant cell

27. Figure 4.6b

28. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Membrane Structure The plasma membrane separates the living cell from its nonliving surroundings.

29. The Plasma Membrane: A Fluid Mosaic of Lipids and Proteins The membranes of cells are composed mostly of: –Lipids –Proteins Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings

30. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The lipids belong to a special category called phospholipids. Phospholipids form a two-layered membrane, the phospholipid bilayer.

31. Figure 4.7a

32. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Most membranes have specific proteins embedded in the phospholipid bilayer. Desmosomes Gap Junctions Tight Junctions

33. Figure 4.7b

34. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Membrane phospholipids and proteins can drift about in the plane of the membrane. This behavior leads to the description of a membrane as a fluid mosaic: –Molecules can move freely within the membrane. –A diversity of proteins exists within the membrane.

35. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Cell Surfaces Most cells secrete materials for coats of one kind or another –That are external to the plasma membrane. These extracellular coats help protect and support cells –And facilitate interactions between cellular neighbors in tissues.

36. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Plant cells have cell walls, –Which help protect the cells, maintain their shape, and keep the cells from absorbing too much water. Animal cells have an extracellular matrix, –Which helps hold cells together in tissues and protects and supports them.

37. The Nucleus and Ribosomes: Genetic Control of the Cell The nucleus is the manager of the cell. –Genes in the nucleus store information necessary to produce proteins. Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings

38. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Structure and Function of the Nucleus The nucleus is bordered by a double membrane called the nuclear envelope. –It contains chromatin. –It contains a nucleolus.

39. Figure 4.8

40. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Ribosomes Ribosomes are responsible for protein synthesis.

41. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings How DNA Controls the Cell DNA controls the cell by transferring its coded information into RNA. –The information in the RNA is used to make proteins.

42. Figure 4.9

43. The Endomembrane System: Manufacturing and Distributing Cellular Products Many of the membranous organelles in the cell belong to the endomembrane system. Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings

44. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Endoplasmic Reticulum The endoplasmic reticulum (ER) –Produces an enormous variety of molecules. –Is composed of smooth and rough ER.

45. Figure 4.10

46. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Rough ER The “roughness” of the rough ER is due to ribosomes that stud the outside of the ER membrane.

47. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The functions of the rough ER include: –Producing two types of membrane proteins –Producing new membrane

48. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings After the rough ER synthesizes a molecule, it packages the molecule into transport vesicles.

49. Figure 4.11

50. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Smooth ER The smooth ER lacks the surface ribosomes of ER and produces lipids, including steroids.

51. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Golgi Apparatus The Golgi apparatus –Works in partnership with the ER. –Refines, stores, and distributes the chemical products of cells.

52. Figure 4.12

53. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Lysosomes A lysosome is a membrane-enclosed sac. –It contains digestive enzymes. –The enzymes break down macromolecules.

54. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Lysosomes have several types of digestive functions. –They fuse with food vacuoles to digest the food. Lysosome Formation

55. Figure 4.13a

56. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings They break down damaged organelles.

57. Figure 4.13b

58. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Vacuoles Vacuoles are membranous sacs. –Two types are the contractile vacuoles of protists and the central vacuoles of plants. Paramecium Vacuole

59. Figure 4.14

60. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings A review of the endomembrane system

61. Figure 4.15

62. Chloroplasts and Mitochondria: Energy Conversion Cells require a constant energy supply to do all the work of life. Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings

63. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Chloroplasts Chloroplasts are the sites of photosynthesis, the conversion of light energy to chemical energy.

64. Figure 4.16

65. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Mitochondria Mitochondria are the sites of cellular respiration, which involves the production of ATP from food molecules.

66. Figure 4.17

67. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Mitochondria and chloroplasts share another feature unique among eukaryotic organelles. –They contain their own DNA. The existence of separate “mini-genomes” is believed to be evidence that –Mitochondria and chloroplasts evolved from free-living prokaryotes in the distant past.

68. The Cytoskeleton: Cell Shape and Movement The cytoskeleton is an infrastructure of the cell consisting of a network of fibers. Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings

69. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Maintaining Cell Shape One function of the cytoskeleton –Is to provide mechanical support to the cell and maintain its shape.

70. Figure 4.18a

71. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The cytoskeleton can change the shape of a cell. –This allows cells like amoebae to move.

72. Figure 4.18b

73. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Cilia and Flagella Cilia and flagella are motile appendages.

74. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Flagella propel the cell in a whiplike motion. Cilia move in a coordinated back-and-forth motion. Paramecium Cilia Cilia and Flagella

75. Figure 4.19a, b

76. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Some cilia or flagella extend from nonmoving cells. –The human windpipe is lined with cilia.

77. Figure 4.19c

78. Evolution Connection: The Origin of Membranes Phospholipids were probably among the organic molecules on the early Earth. When mixed with water, phospholipids spontaneously form membranes. Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings

79. Figure 4.20