3. Chapter: Cells Table of Contents Section 3: VirusesViruses Section 1: Cell Structure Section 2: Viewing CellsViewing Cells

4. A cell is the smallest unit that is capable of performing life functions. All cells have an outer covering called a cell membrane. Inside every cell is a gelatinlike material called cytoplasm. Common Cell Traits Cell Structure 1 1 In the cytoplasm of every cell is hereditary material that controls the life of the cell, DNA.

5. A nerve cell in your leg could be a meter long. A human egg cell is no bigger than the dot on an i. Comparing Cells Cell Structure 1 1 A human red blood cell is about one-tenth the size of a human egg cell.

6. Comparing Cells Cell Structure 1 1 A bacterium is even smaller—8,000 of the smallest bacteria can fit inside one of your red blood cells.

7. Cell size and shape relates to function Though a nerve cell cannot change shape, muscle cells and some blood cells can. In plant stems, some cells are long and hollow and have openings at their ends. Comparing Cells Cell Structure 1 1 These cells carry food and water throughout the plant.

8. Scientists have found that cells can be separated into two groups. Cells without membrane-bound structures are called prokaryotic cells. Cell Types Cell Structure 1 1

9. Cells with membrane-bound structures are called eukaryotic cells. Cell Types Cell Structure 1 1

10. Sketch and Label! Cell Structure 1 1 54321

11. Sketch and Label! Cell Structure 1 1 54321

12. The cells of plants, algae, fungi, and most bacteria are enclosed in a cell wall. Cell walls are tough, rigid outer coverings that protect the cell and give it shape. Cell Organization—Cell Wall Cell Structure 1 1

13. A plant cell wall mostly is made up of a carbohydrate called cellulose. Cell walls also can contain pectin, which is used in jam and jelly, and lignin, which is a compound that makes cell walls rigid. Cell Organization—Cell Wall Cell Structure 1 1 Plant cells responsible for support have a lot of lignin in their walls.

14. The protective layer around all cells is the cell membrane. If cells have cell walls, the cell membrane is inside of the wall. Cell Membrane Cell Structure 1 1 The cell membrane regulates interactions between the cell and the environment.

15. Cells are filled with a gelatinlike substance called cytoplasm. Throughout the cytoplasm is a framework called the cytoskeleton, which helps the cell maintain or change its shape. Cytoplasm Cell Structure 1 1 The cytoskeleton is made up of thin, hollow tubes of protein and thin, solid protein fibers.

16. Cytoplasm Cell Structure 1 1

17. Within the cytoplasm of eukaryotic cells are structures called organelles. Some organelles process energy and others manufacture substances needed by the cell or other cells. Cytoplasm Cell Structure 1 1 Most organelles are surrounded by membranes. The nucleus is usually the largest organelle in a cell.

18. The nucleus directs all cell activities and is separated from the cytoplasm by a membrane. The nucleus contains the instructions for everything the cell does. Organelle # 1: Nucleus Cell Structure 1 1

19. These instructions are found on long, threadlike, hereditary material made of DNA. DNA is the chemical that contains the code for the cell’s structure and activities. Nucleus Cell Structure 1 1 A structure called a nucleolus also is found in the nucleus.

20. In plant cells, food is made in green organelles in the cytoplasm called chloroplasts. Chloroplasts contain the green pigment chlorophyll, which gives many leaves and stems their green color. Organelle # 2: Chloroplasts Cell Structure 1 1

21. Chlorophyll captures light energy that is used to make a sugar called glucose. These help cells do their work. Energy-Processing Organelles Cell Structure 1 1 Many cells, including animal cells, do not have chloroplasts for making food. They must get food from their environment.

22. The energy in food is stored until it is released by the mitochondria. Mitochondria (singular, mitochondrion) are organelles where energy is released from breaking down food into carbon dioxide and water. Organelle # 3: Mitochondria Cell Structure 1 1

23. Cells make their own proteins on small structures called ribosomes. Organelle # 4: Ribosomes Cell Structure 1 1 Proteins are part of cell membranes. Other proteins are needed for chemical reactions that take place in the cytoplasm.

24. Ribosomes receive directions from hereditary material on how, when, and in what order to make specific proteins. Manufacturing Organelles Cell Structure 1 1

25. The endoplasmic reticulum, or ER, extends from the nucleus to the cell membrane. Organelle # 5: ER Cell Structure 1 1 It is a series of folded membranes where materials are processed and moved around inside of the cell.

26. The endoplasmic reticulum may be “rough” or “smooth.” no attached ribosomes is = smooth ER. Processing, Transporting, and Storing Organelles Cell Structure 1 1 rough ER = has ribosomes.

27. Golgi bodies package substances. Organelle # 6: Golgi Cell Structure 1 1

28. The vesicles deliver cellular substances to areas inside the cell. Organelle # 7: vesicle Cell Structure 1 1

29. Organelle # 8: vacuole Cell Structure 1 1 vacuoles = storage of materials. A vacuole can store water, waste products, food, and other cellular materials.

30. Organelle # 9: lysosome Cell Structure 1 1 lysosomes break down food

31. Cell Theory In 1665, Robert Hooke cut a thin slice of cork and looked at it under his microscope. Viewing Cells 2 2 To Hooke, the cork seemed to be made up of empty little boxes, which he named cells.

32. Cell Theory In the 1830s, Matthias Schleiden used a microscope to study plants and concluded that all plants are made of cells. Theodor Schwann, after observing different animal cells, concluded that all animals are made up of cells. Viewing Cells 2 2

33. Cell Theory Several years later, Rudolph Virchow hypothesized that cells divide to form new cells. His observations and conclusions and those of others are summarized in the cell theory. Viewing Cells 2 2

34. Fill in B2 – B4! Viewing Cells 2 2

35. Sketch and Label – Sketch, color, and label both cells on page 41 in your text!! Cell Structure 1 1

36. From Cell to Organism Cell Structure 1 1 A tissue is a group of similar cells that work together to do one job. Tissues are organized into organs.

37. From Cell to Organism Cell Structure 1 1 An organ is a structure made up of two or more different types of tissues that work together.

38. From Cell to Organism Cell Structure 1 1 Click box to view movie. A group of organs working together to perform a certain function is an organ system. Your heart, arteries, veins, and capillaries make up your cardiovascular system.

39. Question 1 Which of these cells is a bacterium? Section Check 1 1

40. Answer Prokaryotic cells are only one-celled organisms, such as bacteria. Section Check 1 1

41. Question 2 Answers: A: Nucleus B: Membrane C: Organelle D: Ribosome Which part of the cell gives it shape? Section Check 1 1

42. Question 3 Answers: A: Membrane B: Wall C: Cytoplasm D: Nucleus In what part of the cell is the cytoskeleton found? Section Check 1 1

43. Question 4 Answers: A: eukaryotic B: plant C: animal D: prokaryotic Which cell type LACKS a nucleus? Section Check 1 1

44. Question 5 Answers: A: package things B: transport things C: make proteins D: make energy What do ribosomes do? Section Check 1 1

45. Magnifying Cells To see most cells, you need to use a microscope. A microscope has one or more lenses that enlarge the image of an object as though you are walking closer to it. Viewing Cells 2 2

46. Early Microscopes Made things larger, but not always CLEARER. In the mid 1600s, Antoine van Leeuwenhoek, a Dutch fabric merchant, made a simple microscope with a tiny glass bead for a lens. Viewing Cells 2 2

47. Early Microscopes Viewing Cells 2 2 His microscope could magnify up to 270 times. Today you would say his lens had a power of 270×.

48. Modern Microscopes Use lenses to bend light. Can be simple or compound. Viewing Cells 2 2 Stereo: more of a 3-D image. Powers multiplied together = total magnification..

49. Modern Microscopes The compound light microscope has two sets of lenses—eyepiece lenses and objective lenses. The eyepiece lenses are mounted in one or two tubelike structures. Viewing Cells 2 2 Compound light microscopes usually have two to four movable objective lenses.

50. Magnification The powers of the eyepiece and objective lenses determine the total magnifications of a microscope. If the eyepiece lens has a power of 10× and the objective lens has a power of 43×, then the total magnification is 430× (10× times 43×). Viewing Cells 2 2

51. Electron Microscopes Things that are too small to be seen with other microscopes can be viewed with an electron microscope. Instead of using lenses to direct beams of light, an electron microscope uses a magnetic field in a vacuum to direct beams of electrons. Viewing Cells 2 2

52. Electron Microscopes Scanning electron microscopes (SEM) produce a realistic, three-dimensional image. Only the surface of the specimen can be observed using an SEM. Viewing Cells 2 2

53. Electron Microscopes Viewing Cells 2 2 Transmission electron microscopes (TEM) produce a two-dimensional image of a thinly-sliced specimen. Results must be photographed or captured in other ways.

54. Electron Microscopes A metal probe is placed near the surface of the specimen and electrons flow from the tip. The hills and valleys of the specimen’s surface are mapped. Viewing Cells 2 2

55. 2 2 Section Check Question 1 Who developed a microscope using a tiny glass bead for a lens? A. Antoine van Leeuwenhoek B. Edward Jenner C. Matthias Schleiden D. Theodor Schwann

56. 2 2 Section Check Answer Antoine van Leeuwenhoek

57. 2 2 Section Check Question 2 How many lenses does a simple microscope have? A. 0 B. 1 C. 2 D. 4

58. 2 2 Section Check Answer

59. 2 2 Section Check Question 3 The conclusions listed in this table are known as the _______.

60. 2 2 Section Check A. Cell Theory B. Koch’s Rules C. Law of Independent Assortment D. Principles of Natural Selection

61. 2 2 Section Check Answer Cell Theory

62. What are viruses? A virus is a strand of hereditary material surrounded by a protein coating. Viruses don’t have a nucleus, other organelles, or a cell membrane. Viruses have a variety of shapes. Viruses 3 3

63. How do viruses multiply? All viruses can do is make copies of themselves. Crystallized forms of some viruses can be stored for years. Viruses 3 3 only with the help of a living cell called a host cell.

64. How do viruses multiply? Viruses 3 3 Then, if they enter an organism, they can multiply quickly. Once a virus is inside of a host cell, the virus can act in two ways. It can either be active or it can become latent, which is an inactive stage

65. Active Viruses Viruses 3 3 When a virus enters a cell and is active, it causes the host cell to make new viruses. This process destroys the host cell. Click image to view movie.

66. Latent Viruses Viruses 3 3 Some viruses can be latent, which means that after it enters a cell, its hereditary material can become part of the cell’s. It does not immediately make new viruses or destroy the cell. As the host cell reproduces, the viral DNA is copied. Click image to view movie.

67. Latent Viruses Viruses 3 3 A virus can be latent for many years. Then, at any time, certain conditions can activate the virus. If you have had a cold sore on your lip, a latent virus in your body has become active.

68. How do viruses affect organisms? Viruses 3 3 Viruses attack animals, plants, fungi, protists, and all prokaryotes. Some viruses can infect only specific kinds of cells. Many viruses are limited to one host species or to one type of tissue within that species. A few viruses affect a broad range of hosts.

69. How do viruses affect organisms? Viruses 3 3 A virus cannot move by itself, but it can reach a host’s body in several ways. It can be carried onto a plant’s surface by the wind or it can be inhaled by an animal. In a viral infection, the virus first attaches to the surface of the host cell.

70. How do viruses affect organisms? Viruses 3 3 The virus and the place where it attaches must fit together exactly. Because of this, most viruses attack only one kind of host cell.

71. How do viruses affect organisms? Viruses 3 3 Viruses that infect bacteria are called bacteriophages.

72. Vaccines have been made to prevent many diseases, including measles, mumps, smallpox, chicken pox, polio, and rabies. Fighting Viruses Viruses 3 3 Vaccines are used to prevent disease. A vaccine is made from weakened virus particles that can’t cause disease anymore.

73. Jenner noticed that people who got a disease called cowpox didn’t get smallpox. The First Vaccine Viruses 3 3 Edward Jenner is credited with developing the first vaccine in 1796. He developed a vaccine for smallpox, a disease that was still feared in the early twentieth century.

74. Jenner didn’t know he was fighting a virus. The First Vaccine Viruses 3 3 He prepared a vaccine from the sores of people who had cowpox. When injected into healthy people, the cowpox vaccine protected them from smallpox. At that time, no one understood what caused disease or how the body fought disease.

75. Interferons are proteins that are produced rapidly by virus-infected cells and move to noninfected cells in the host. Treating Viral Diseases Viruses 3 3 Antibiotics treat bacterial infections but are not effective against viral diseases. One way your body can stop viral infections is by making interferons.

76. A few drugs show some effectiveness against viruses but some have limited use because of their adverse side effects. Treating Viral Diseases Viruses 3 3 Interferons cause the noninfected cells to produce protective substances. Antiviral drugs can be given to infected patients to help fight a virus.

77. Improving sanitary conditions Preventing Viral Diseases Viruses 3 3 Public health measures for stopping or slowing viral diseases includes: Vaccinating people Quarantining patients Controlling animals that spread disease

78. Preventing Viral Diseases Viruses 3 3 Annual rabies vaccinations of pets and farm animals protect them and humans from infection. To control the spread of rabies in wild animals such as coyotes and wolves, wildlife workers place bait containing an oral rabies vaccine where wild animals will find it.

79. Research with Viruses Viruses 3 3 Through research, scientists are discovering helpful uses for some viruses. Gene therapy substitutes normal hereditary material for a cell’s defective hereditary material. The normal material is enclosed in viruses that “infect” targeted cells.

80. Research with Viruses Viruses 3 3 In gene therapy, new hereditary material replaces the defective hereditary material. Using gene therapy, scientists hope to help people with genetic disorders and find a cure for cancer.

81. Question 1 Answers: A: Bacterium B: Virus C: Eukaryote D: Prokaryote A _______ is a nonliving strand of hereditary material surround by a protein coating. Section Check 3 3

82. 3 3 Question 2 Which happens to the host cell after the active virus is duplicated? A. It divides through cell division B. It is destroyed C. It functions normally D. It continues to produce more and more new viruses

83. 3 3 Section Check Answer

84. 3 3 Section Check Question 3 Who developed the first vaccine? A. Edward Jenner B. Gregor Mendel C. Reginald C. Punnett D. Theodor Schwann

85. 3 3 Section Check Answer Edward Jenner

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