1. Cell Structure and Function Chapter 4

2. 4.1 What is a Cell?  Each cell has a plasma membrane, cytoplasm, and a nucleus (in eukaryotic cells) or a nucleoid (in prokaryotic cells)

3. Fig. 4.3, p. 52 DNA cytoplasm plasma membrane a Bacterial cell (prokaryotic)

4. Fig. 4.3, p. 52 DNA in nucleus cytoplasm plasma membrane b Plant cell (eukaryotic)

5. Fig. 4.3, p. 52 DNA in nucleus cytoplasm plasma membrane c Animal cell (eukaryotic)

6. Animation: Overview of cells CLICK HERE TO PLAY

7. Components of Cell Membranes  Lipid bilayer

8. “head” two “tails” Fig. 4.4, p. 53

9. fluid lipid bilayer

10. Fig. 4.4, p. 53 one layer of lipids one layer of lipids membrane protein extracellular environment cytoplasm

11. Cell Size and Shape  Surface-to-volume ratio limits cell size

12. Key Concepts: WHAT ALL CELLS HAVE IN COMMON  Each cell has a plasma membrane, a boundary between its interior and the outside environment  The interior consists of cytoplasm and an innermost region of DNA

13. Animation: Surface-to-volume ratio CLICK HERE TO PLAY

14. 4.2 How Do We See Cells?  Three key points of the cell theory: All organisms consist of one or more cells The cell is the smallest unit that retains the capacity for life A cell arises from the growth and division of another cell

15. Relative Sizes

16. Fig. 4.6, p. 54

17. Microscopes  Different microscopes use light or electrons to reveal details of cell shapes or structures

18. Fig. 4.7, p. 55 light source (in base) Ocular lens enlarges primary image formed by objective lenses. Objective lenses (those closest to specimen) form the primary image. Most compound light microscopes have several. stage supports microscope slide Condenser lenses focus light rays through specimen. illuminator path of light rays (bottom to top) to eye prism that directs rays to ocular lens

19. Animation: How a light microscope works CLICK HERE TO PLAY

20. incoming electron beam condenser lens (focuses a beam of electrons onto specimen) objective lens intermediate lens projector lens viewing screen (or photographic film) specimen Fig. 4.7, p. 55

21. Animation: How an electron microscope works CLICK HERE TO PLAY

22. Five Different Views

23. Key Concepts: MICROSCOPES  Microscopic analysis supports three generalizations of the cell theory: Each organism consists of one or more cells and their products A cell has a capacity for independent life Each new cell is descended from a living cell

24. 4.3 Membrane Structure and Function  Each cell membrane is a boundary (lipid bilayer) that controls the flow of substances across it  Fluid mosaic model Membrane is composed of phospholipids, sterols, proteins, and other components Phospholipids drift within the bilayer

25. Membrane Proteins  Many proteins are embedded in or attached to cell membrane surfaces Receptors, transporters, communication proteins, and adhesion proteins  Plasma (outer) membrane also incorporates recognition proteins

26. Common Membrane Proteins

27. Fig. 4.9, p. 57 A calcium pump moves calcium ions across the membrane; requires ATP energy. EXTRACELLULAR FLUID phospholipid LIPID BILAYER CYTOPLASM protein filaments of the cytoskeleton B cell receptor. It binds to bacteria, other foreign agents. Recognition protein that identifies a cell as belonging to one’s own body. A glucose transporter allows glucose to cross the membrane through a channel in its interior. An ATP synthase, which makes ATP when H+ crosses a membrane through its interior.

28. Membrane Structure Studies

29. Fig. 4.10, p. 57 proteins from both cells in fused membrane human cellmouse cell fusion into hybrid cell

30. Key Concepts: COMPONENTS OF CELL MEMBRANES  All cell membranes are mostly a lipid bilayer (two layers of lipids) and a variety of proteins  The proteins have diverse tasks, including control over which water-soluble substances cross the membrane at any given time

31. Animation: Lipid bilayer organization CLICK HERE TO PLAY

32. Animation: Cell membranes CLICK HERE TO PLAY

33. 4.4 Introducing Prokaryotic Cells  Bacteria and archaeans The simplest cells The groups with greatest metabolic diversity  Biofilms Shared living arrangements of prokaryotes

34. Prokaryote Structure  Cell wall Surrounds plasma membrane  Flagella Used for motion  Pili Protein filaments used for attachment “Sex” pilus transfers genetic material

35. Prokaryote Structure

37. Fig. 4.11, p. 58 bacterial flagellum pilus plasma membrane DNA in nucleoid cytoplasm, with ribosomes Most prokaryotic cells have a cell wall outside the plasma membrane, and many have a thick, jellylike capsule around the wall. cell wall capsule

38. Animation: Typical prokaryotic cell CLICK HERE TO PLAY

39. 4.5 Microbial Mobs  Biofilm formation

40. Key Concepts: PROKARYOTIC CELLS  Archaeans and bacteria are prokaryotic cells which have few, if any, internal membrane- enclosed compartments  In general, they are the smallest and structurally the simplest cells

41. 4.6 Introducing Eukaryotic Cells  Start with a nucleus and other organelles Carry out specialized functions inside a cell

42. Fig. 4.14, p. 60 mitochondria plasma membrane nucleus

43. Fig. 4.14, p. 60 nucleus cell wall plasma membrane central vacuole chloroplast

44. Components of Eukaryotic Cells

45. 4.7 Components of The Nucleus  Nucleus separates DNA from cytoplasm Chromatin (all chromosomal DNA with proteins) Chromosomes (condensed)  Nucleolus assembles ribosome subunits  Nuclear envelope encloses nucleoplasm Pores, receptors, transport proteins

46. Nucleus and Nuclear Envelope

49. Animation: Nuclear envelope CLICK HERE TO PLAY

50. Fig. 4.15, p. 61 cytoplasm nuclear envelope chromatin nucleolus

51. Fig. 4.15, p. 61 nuclear envelope’s outer lipid bilayer merging with an ER membrane nucleus chromatin pore across the nuclear envelope nucleoplasm nucleolus

52. Fig. 4.15, p. 61 cytoplasm nuclear pore nuclear envelope (two lipid bilayers)

53. 4.8 The Endomembrane System  Endoplasmic reticulum (ER) An extension of the nuclear envelope RER modifies new polypeptide chains SER makes lipids; other metabolic functions  Golgi bodies Further modify polypeptides Assemble lipids

54. The Endomembrane System  Vesicles Endocytic and exocytic: Transport or store polypeptides and lipids Peroxisomes: Digest fatty acids and amino acids; break down toxins and metabolic by-products Lysosomes: Intracellular digestion (animals) Central vacuole: Storage; fluid pressure (plants)

55. Endomembrane System

58. Fig. 4.16, p. 62 vesicles nucleus rough ER smooth ER Golgi body

59. Animation: The endomembrane system CLICK HERE TO PLAY

60. Fig. 4.16, p. 62 the cell nucleus chromatin nucleolusnuclear envelope (two lipid bilayers) pore cytoplasm ribosomevesicle rough ER

61. Fig. 4.16, p. 62 smooth ER channel, cross-section plasma membrane Golgi bodysmooth ER budding vesicle

62. 4.9 Mitochondria and Chloroplasts  Mitochondria Break down organic compounds by aerobic respiration (oxygen-requiring) Produce ATP  Chloroplasts Produce sugars by photosynthesis

63. Mitochondria and Chloroplasts

64. Fig. 4.18, p. 63 thylakoids (inner membrane system folded into flattened disks) two outer membranes stroma

65. Animation: Structure of a chloroplast CLICK HERE TO PLAY

66. Animation: Structure of a mitochondrion CLICK HERE TO PLAY

67. 4.10 Visual Summary: Plant Cells

68. Visual Summary: Animal Cells

69. CENTRAL VACUOLE LYSOSOME- LIKE VESICLE GOLGI BODY SMOOTH ER ROUGH ER RIBOSOMES NUCLEUS CHLOROPLAST CYTOSKELETON MITOCHONDRION PLASMODESMA PLASMA MEMBRANE CELL WALL Fig. 4.19, p.65 nuclear envelope nucleolus DNA in nucleoplasm microtubules microfilaments intermediate filaments (not shown) a Typical plant cell components.

70. CYTOSKELETON MITOCHONDRION CENTRIOLES LYSOSOME GOLGI BODY SMOOTH ER ROUGH ER RIBOSOMES NUCLEUS PLASMA MEMBRANE microtubules microfilaments intermediate filaments nuclear envelope nucleolus DNA in nucleoplasm b Typical animal cell components. Fig. 4.19, p. 64

71. PLASMA MEMBRANE MITOCHONDRION CENTRIOLES RIBOSOMES ROUGH ER SMOOTH ER GOLGI BODY LYSOSOME CYTOSKELETON microtubules microfilaments intermediate filaments NUCLEUS nuclear envelope nucleolus DNA in nucleoplasm b Typical animal cell components. Fig. 4-19, p. 64 Stepped Art

72. Animation: Common eukaryotic organelles CLICK HERE TO PLAY

73. 4.11 Cell Surface Specializations  Most prokaryotes, protists, fungi, all plant cells have a cell wall around their plasma membrane Protects, supports, maintains cell shape Primary and secondary cell walls  Plasmodesmata across cell walls connect plant cells

74. Plant Cell Walls

75. Fig. 4.20, p. 66 pipeline made of abutting cell walls plasma membrane middle lamella cytoplasm primary cell wall secondary cell wall (added in layers) primary cell wall

76. Plant Cell Walls

77. Fig. 4.20, p. 66 middle lamella Plasmodesmata plasmodesma middle lamella

78. Animation: Plant cell walls CLICK HERE TO PLAY

79. Plant Cuticle  Protective surface secretion, limits water loss

80. Fig. 4.21, p. 67 photosynthetic cell inside leaf thick, waxy cuticle at leaf surface cell of leaf epidermis

81. Extracellular Matrixes  Surrounds cells of specific tissues

82. Animal Cell Junctions  Connect cells of animals Adhering junctions, tight junctions, gap junctions

83. Fig. 4.23, p. 67 adhering junction free surface of epithelial tissue different kinds of tight junctions gap junction basement membrane (extracellular matrix)

84. Animation: Animal cell junctions CLICK HERE TO PLAY

85. Key Concepts: EUKARYOTIC CELLS  Cells of protists, plants, fungi, and animals are eukaryotic; they have a nucleus and other membrane-enclosed compartments  They differ in internal parts and surface specializations

86. 4.12 The Dynamic Cytoskeleton  Components of the cytoskeleton Microtubules Microfilaments Intermediate filaments (in most)

87. Fig. 4.12, p. 59

90. Components of the Cytoskeleton

91. Fig. 4.24, p. 68 tubulin subunit 25 nm

92. Fig. 4.24, p. 68 actin subunit 5–7 nm

93. Fig. 4.24, p. 68 8–12 nm one polypeptide chain

94. Cytoskeleton Function  Organizes and moves cell parts  Reinforces cell shape  Interactions between motor proteins and microtubules in cilia, flagella, and pseudopods can move the whole cell

95. Animation: Cytoskeletal components CLICK HERE TO PLAY

96. Motor Protein: Kinesin  Moves vesicles along microtubules

97. Animation: Motor proteins CLICK HERE TO PLAY

98. Flagellum and Pseudopods

99. Eukaryotic Flagella and Cilia: Dynein

101. Fig. 4.27, p. 69 dynein arms protein spokes plasma membrane pair of microtubules in a central sheath pair of microtubules dynein arms basal body

102. Animation: Flagella structure CLICK HERE TO PLAY

103. Key Concepts: A LOOK AT THE CYTOSKELETON  Diverse protein filaments reinforce a cell’s shape and keep its parts organized  As some filaments lengthen and shorten, they move chromosomes or other structures to new locations