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Start here_ch03_lecture

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  • 1. Chapter 3 Cell Structure and Function
  • 2. Processes of Life
    • Growth
    • Reproduction
    • Responsiveness
    • Metabolism
  • 3. Processes of Life
  • 4. Prokaryotic & Eukaryotic Cells: An Overview [INSERT FIGURE 3.1]
  • 5. Prokaryotic & Eukaryotic Cells: An Overview
    • Prokaryotes
      • Do not have membrane surrounding their DNA; lack a nucleus
      • Lack various internal structures bound with phospholipid membranes
      • Are small, ~1.0 µm in diameter
      • Have a simple structure
      • Composed of bacteria and archaea
  • 6. Prokaryotic & Eukaryotic Cells: An Overview [INSERT FIGURE 3.2]
  • 7. Prokaryotic & Eukaryotic Cells: An Overview
    • Eukaryotes
      • Have membrane surrounding their DNA; have a nucleus
      • Have internal membrane-bound organelles
      • Are larger, 10-100 µm in diameter
      • Have more complex structure
      • Composed of algae, protozoa, fungi, animals, and plants
  • 8. Prokaryotic & Eukaryotic Cells: An Overview [INSERT FIGURE 3.3]
  • 9. Prokaryotic & Eukaryotic Cells: An Overview [INSERT FIGURE 3.4]
  • 10. External Structures of Prokaryotic Cells
    • Glycocalyces
      • Gelatinous, sticky substance surrounding the outside of the cell
      • Composed of polysaccharides, polypeptides, or both
  • 11. External Structures of Prokaryotic Cells
    • Two Types of Glycocalyces
      • Capsule
        • Composed of organized repeating units of organic chemicals
        • Firmly attached to cell surface
        • Protects cells from drying out
        • May prevent bacteria from being recognized and destroyed by host
      • Slime layer
        • Loosely attached to cell surface
        • Water soluble
        • Protects cells from drying out
        • Sticky layer that allows prokaryotes to attach to surfaces
  • 12. External Structures of Prokaryotic Cells [INSERT FIGURE 3.5]
  • 13. External Structures of Prokaryotic Cells Animation: Motility
  • 14. External Structures of Prokaryotic Cells
    • Flagella
      • Are responsible for movement
      • Have long structures that extend beyond cell surface
      • Are not present on all prokaryotes
  • 15. External Structures of Prokaryotic Cells
    • Flagella
      • Structure
        • Composed of filament, hook, and basal body
        • Flagellin protein (filament) deposited in a helix at the lengthening tip
        • Base of filament inserts into hook
        • Basal body anchors filament and hook to cell wall by a rod and a series of either two or four rings of integral proteins
        • Filament capable of rotating 360º
  • 16. External Structures of Prokaryotic Cells Animation: Flagella Structure
  • 17. External Structures of Prokaryotic Cells [INSERT FIGURE 3.6]
  • 18. External Structures of Prokaryotic Cells
  • 19. External Structures of Prokaryotic Cells Animation: Flagella Arrangement
  • 20. External Structures of Prokaryotic Cells [INSERT FIGURE 3.8]
  • 21. External Structures of Prokaryotic Cells
    • Flagella
      • Function
        • Rotation propels bacterium through environment
        • Rotation reversible, can be clockwise or counterclockwise
        • Bacteria move in response to stimuli (taxis)
          • Runs
          • Tumbles
  • 22. External Structures of Prokaryotic Cells [INSERT FIGURE 3.9]
  • 23. External Structures of Prokaryotic Cells Animation: Flagella Movement
  • 24. External Structures of Prokaryotic Cells
    • Fimbriae and Pili
      • Rod-like proteinaceous extensions
  • 25. External Structures of Prokaryotic Cells
      • Fimbriae
        • Sticky, bristlelike projections
        • Used by bacteria to adhere to one another, to hosts, and to substances in environment
        • Shorter than flagella
        • May be hundreds per cell
        • Serve an important function in biofilms
  • 26. External Structures of Prokaryotic Cells [INSERT FIGURE 3.10]
  • 27. External Structures of Prokaryotic Cells
    • Pili
      • Tubules composed of pilin
      • Also known as conjugation pili
      • Longer than fimbriae but shorter than flagella
      • Bacteria typically only have one or two per cell
      • Mediate the transfer of DNA from one cell to another (conjugation)
  • 28. External Structures of Prokaryotic Cells [INSERT FIGURE 3.11]
  • 29. Prokaryotic Cell Walls
    • Provide structure and shape and protect cell from osmotic forces
    • Assist some cells in attaching to other cells or in eluding antimicrobial drugs
    • Not present in animal cells, so can target cell wall of bacteria with antibiotics
    • Bacteria and archaea have different cell wall chemistry
  • 30. Prokaryotic Cell Wall
    • Bacterial Cell Walls
      • Most have cell wall composed of peptidoglycan
      • Peptidoglycan is composed of sugars, NAG, and NAM
      • Chains of NAG and NAM attached to other chains by tetrapeptide crossbridges
        • Bridges may be covalently bonded to one another
        • Bridges may be held together by short connecting chains of amino acids
      • Scientists describe two basic types of bacterial cell walls: Gram-positive and Gram-negative
  • 31. External Structures of Prokaryotic Cells [INSERT FIGURE 3.12]
  • 32. External Structures of Prokaryotic Cells [INSERT FIGURE 3.13]
  • 33. Prokaryotic Cell Walls
    • Bacterial Cell Walls
      • Gram-positive cell walls
        • Relatively thick layer of peptidoglycan
        • Contain unique polyalcohols called teichoic acids
          • Some covalently linked to lipids, forming lipoteichoic acids that anchor peptidoglycan to cell membrane
        • Retain crystal violet dye in Gram staining procedure; so appear purple
        • Up to 60% mycolic acid in acid-fast bacteria helps cells survive desiccation
  • 34. Prokaryotic Cell Walls [INSERT FIGURE 3.14a]
  • 35. Prokaryotic Cell Walls
    • Bacterial Cell Walls
      • Gram-negative cell walls
        • Have only a thin layer of peptidoglycan
        • Bilayer membrane outside the peptidoglycan contains phospholipids, proteins, and lipopolysaccharide (LPS)
        • May be impediment to the treatment of disease
        • Appear pink following Gram staining procedure
  • 36. Prokaryotic Cell Walls [INSERT FIGURE 3.14b]
  • 37. Prokaryotic Cell Walls
    • Archaeal Cell Walls
      • Do not have peptidoglycan
      • Contains variety of specialized polysaccharides and proteins
      • Gram-positive archaea stain purple
      • Gram-negative archaea stain pink
  • 38. Prokaryotic Cytoplasmic Membranes
    • Structure
      • Referred to as phospholipid bilayer; composed of lipids and associated proteins
      • Approximately half composed of proteins that act as recognition proteins, enzymes, receptors, carriers, or channels
        • Integral proteins
        • Peripheral proteins
        • Glycoproteins
      • Fluid mosaic model describes current understanding of membrane structure
  • 39. Prokaryotic Cytoplasmic Membranes [INSERT FIGURE 3.15]
  • 40. Prokaryotic Cytoplasmic Membranes
    • Function
      • Energy storage
      • Harvest light energy in photosynthetic prokaryotes
      • Selectively permeable
      • Naturally impermeable to most substances
      • Proteins allow substances to cross membrane
        • Occurs by passive or active processes
      • Maintain concentration and electrical gradient
        • Chemicals concentrated on one side of the membrane or the other
        • Voltage exists across the membrane
  • 41. Prokaryotic Cytoplasmic Membranes [INSERT FIGURE 3.16]
  • 42. Prokaryotic Cytoplasmic Membranes
    • Function
      • Passive processes
        • Diffusion
        • Facilitated diffusion
        • Osmosis
          • Isotonic solution
          • Hypertonic solution
          • Hypotonic solution
  • 43. Prokaryotic Cytoplasmic Membranes [INSERT FIGURE 3.17]
  • 44. Prokaryotic Cytoplasmic Membranes [INSERT FIGURE 3.18]
  • 45. Prokaryotic Cytoplasmic Membranes [INSERT FIGURE 3.19]
  • 46. Prokaryotic Cytoplasmic Membranes
    • Function
      • Active processes
        • Active transport
          • Utilize permease proteins and expend ATP
          • Uniport
          • Antiport
          • Symport
      • Group translocation
        • Substance chemically modified during transport
  • 47. Prokaryotic Cytoplasmic Membranes [INSERT FIGURE 3.20]
  • 48. Prokaryotic Cytoplasmic Membranes Animation: Active Transport Overview
  • 49. Prokaryotic Cytoplasmic Membranes Animation: Active Transport Types
  • 50. Prokaryotic Cytoplasmic Membranes [INSERT FIGURE 3.21]
  • 51. Prokaryotic Cytoplasmic Membranes [INSERT TABLE 3.2]
  • 52. Cytoplasm of Prokaryotes
    • Cytosol – liquid portion of cytoplasm
    • Inclusions – may include reserve deposits of chemicals
    • Endospores – unique structures produced by some bacteria that are a defensive strategy against unfavorable conditions
  • 53. Cytoplasm of Prokaryotes
  • 54. Cytoplasm of Prokaryotes
    • Nonmembranous Organelles
      • Ribosomes – sites of protein synthesis
      • Cytoskeleton – plays a role in forming the cell’s basic shape
  • 55. Cytoplasm of Prokaryotes [INSERT FIGURE 3.23]
  • 56. External Structure of Eukaryotic Cells
    • Glycocalyces
      • Never as organized as prokaryotic capsules
      • Help anchor animal cells to each other
      • Strengthen cell surface
      • Provide protection against dehydration
      • Function in cell-to-cell recognition and communication
  • 57. Eukaryotic Cell Walls & Cytoplasmic Membranes
    • Fungi, algae, plants, and some protozoa have cell walls but no glycocalyx
    • Composed of various polysaccharides
      • Cellulose found in plant cell walls
      • Fungal cell walls composed of cellulose, chitin, and/or glucomannan
      • Algal cell walls composed of cellulose, proteins, agar, carrageenan, silicates, algin, calcium carbonate, or a combination of these
  • 58. Eukaryotic Cell Walls & Cytoplasmic Membranes [INSERT FIGURE 3.24]
  • 59. Eukaryotic Cell Walls & Cytoplasmic Membranes
    • All eukaryotic cells have cytoplasmic membrane
    • Are a fluid mosaic of phospholipids and proteins
    • Contain steroid lipids to help maintain fluidity
    • Contain regions of lipids and proteins called membrane rafts
    • Control movement into and out of cell
      • Use diffusion, facilitated diffusion, osmosis, and active transport
      • Perform endocytosis; phagocytosis if solid substance and pinocytosis if liquid substance
      • Exocytosis enables substances to be exported from cell
  • 60. Eukaryotic Cell Walls & Cytoplasmic Membranes [INSERT FIGURE 3.25]
  • 61. Eukaryotic Cell Walls & Cytoplasmic Membranes [INSERT TABLE 3.3]
  • 62. Eukaryotic Cell Walls & Cytoplasmic Membranes [INSERT FIGURE 3.26]
  • 63. Cytoplasm of Eukaryotes
  • 64. Cytoplasm of Eukaryotes
    • Flagella
      • Structure and arrangement
        • Shaft composed of tubulin arranged to form microtubules
        • “ 9 + 2” arrangement of microtubules in all flagellated eukaryotes
        • Filaments anchored to cell by basal body; no hook
        • Basal body has “9 + 0” arrangement of microtubules
        • May be single or multiple; generally found at one pole of cell
  • 65. Cytoplasm of Eukaryotes
    • Flagella
      • Function
        • Do not rotate, but undulate rhythmically
  • 66. Cytoplasm of Eukaryotes [INSERT FIGURE 3.28a & b]
  • 67. Cytoplasm of Eukaryotes
    • Cilia
      • Shorter and more numerous than flagella
      • Composed of tubulin in “9 + 2” and “9 + 0” arrangements
      • Coordinated beating propels cells through their environment
      • Also used to move substances past the surface of the cell
  • 68. Cytoplasm of Eukaryotes [INSERT FIGURE 3.27c]
  • 69. Cytoplasm of Eukaryotes
    • Other Nonmembranous Organelles
      • Ribosomes
        • Larger than prokaryotic ribosomes (80S versus 70S)
        • Composed of 60S and 40S subunits
      • Cytoskeleton
        • Extensive
        • Functions
          • Anchors organelles
          • Cytoplasmic streaming and movement of organelles
          • Movement during endocytosis and amoeboid action
          • Produces basic shape of the cell
        • Made up of tubulin microtubules, actin microfilaments, and intermediate filaments
  • 70. Cytoplasm of Eukaryotes [INSERT FIGURE 3.29]
  • 71. Cytoplasm of Eukaryotes
    • Other Nonmembranous Organelles
      • Centrioles and centrosome
        • Centrioles play a role in mitosis, cytokinesis, and in formation of flagella and cilia
        • Centrioles composed of “9 + 0” arrangement of microtubules
        • Centrosome is region of cytoplasm where centrioles are found
  • 72. Cytoplasm of Eukaryotes [INSERT FIGURE 3.30]
  • 73. Cytoplasm of Eukaryotes
    • Membranous Organelles
      • Nucleus
        • Often largest organelle in cell
        • Contains most of the cell’s DNA
        • Semi-liquid portion called nucleoplasm
        • One or more nucleoli present in nucleoplasm; RNA synthesized in nucleoli
        • Nucleoplasm contains chromatin – masses of DNA associated with histones
        • Surrounded by nuclear envelope – double membrane composed of two phospholipid bilayers
        • Nuclear envelope contains nuclear pores
  • 74. Cytoplasm of Eukaryotes [INSERT FIGURE 3.31]
  • 75. Cytoplasm of Eukaryotes
    • Membranous Organelles
      • Endoplasmic reticulum
        • Netlike arrangement of flattened, hollow tubules continuous with nuclear envelope
        • Functions as transport system
        • Two forms
          • Smooth endoplasmic reticulum (SER) – plays role in lipid synthesis
          • Rough endoplasmic reticulum (RER) – ribosomes attached to its outer surface; transports proteins produced by ribosomes
  • 76. Cytoplasm of Eukaryotes [INSERT FIGURE 3.32]
  • 77. Cytoplasm of Eukaryotes
    • Membranous Organelles
      • Golgi body
        • Receives, processes, and packages large molecules for export from cell
        • Packages molecules in secretory vesicles that fuse with cytoplasmic membrane
        • Composed of flattened hollow sacs surrounded by phospholipid bilayer
        • Not in all eukaryotic cells
  • 78. Cytoplasm of Eukaryotes [INSERT FIGURE 3.33]
  • 79. Cytoplasm of Eukaryotes
    • Membranous Organelles
      • Lysosomes, peroxisomes,vacuoles, and vesicles
        • Store and transfer chemicals within cells
        • May store nutrients in cell
        • Lysosomes contain catabolic enzymes
        • Peroxisomes contain enzymes that degrade poisonous wastes
  • 80. Cytoplasm of Eukaryotes [INSERT FIGURE 3.34]
  • 81. Cytoplasm of Eukaryotes [INSERT FIGURE 3.35]
  • 82. Cytoplasm of Eukaryotes
    • Membranous Organelles
      • Mitochondria
        • Have two membranes composed of phospholipid bilayer
        • Produce most of cell’s ATP
        • Interior matrix contains 70S ribosomes and circular molecule of DNA
  • 83. Cytoplasm of Eukaryotes [INSERT FIGURE 3.36]
  • 84. Cytoplasm of Eukaryotes
    • Membranous Organelles
      • Chloroplasts
        • Light-harvesting structures found in photosynthetic eukaryotes
        • Have two phospholipid bilayer membranes and DNA
        • Have 70S ribosomes
  • 85. Cytoplasm of Eukaryotes [INSERT FIGURE 3.37]
  • 86. Cytoplasm of Eukaryotes [INSERT TABLE 3.4]
  • 87. Cytoplasm of Eukaryotes
    • Endosymbiotic Theory
      • Eukaryotes formed from union of small aerobic prokaryotes with larger anaerobic prokaryotes
      • smaller prokaryotes became internal parasites
        • Parasites lost ability to exist independently; retained portion of DNA, ribosomes, and cytoplasmic membranes
        • Larger cell became dependent on parasites for aerobic ATP production
        • Aerobic prokaryotes evolved into mitochondria
        • Similar scenario for origin of chloroplasts
      • Not universally accepted
  • 88. Cytoplasm of Eukaryotes [INSERT TABLE 3.5]