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Tour of the Cell

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  • 1. A Tour of the Cell
    Tour Guide…
    Mrs. Erin Fortenberry
  • 2. Question ?
    Can cells be seen with the naked eye?
    Yes, a few are large enough, but most require the use of a microscope.
  • 3.
  • 4. Microscope History
    1590 - Janseen Brothers invent the compound microscope.
    1665 - Robert Hooke “discovers” cells in cork.
    Early 1700’s - von Leeuwenhoek makes many observations of cells including bacteria.
  • 5. Light Microscope - LM
    Uses visible light to illuminate the object.
    Relatively inexpensive type of microscope.
    Can examine live or dead objects.
  • 6. Electron Microscopes
    Use beams of electrons instead of light.
    Invented in 1939, but not used much until after WWII.
  • 7. TEM
    SEM
  • 8. Advantages
    Much higher magnifications.
    Magnifications of 50,000X or higher are possible.
    Can get down to atomic level in some cases.
  • 9. Disadvantages
    Need a Vacuum.
    Specimen must stop the electrons.
    High cost of equipment.
    Specimen preparation.
  • 10. Cell Biology or Cytology
    Cyto = cell
    - ology = study of
  • 11. History of Cells
    Robert Hooke - Observed cells in cork.
    Coined the term "cells” in 1665.
  • 12. History of Cells
    1833 - Robert Brown, discovered the nucleus.
    1838 - M.J. Schleiden, all plants are made of cells.
    1839 - T. Schwann, all animals are made of cells.
  • 13. Cell Theory
    All living matter is composed of one or more cells.
    The cell is the structural and functional unit of life.
  • 14. Types of Cells
    Prokaryotic - lack a nucleus and other membrane bounded structures.
    Eukaryotic - have a nucleus and other membrane bounded structures.
  • 15. Prokaryotic
    Eukaryotic
    Nucleus
  • 16. Basic Cell Organization
    Membrane
    Nucleus
    Cytoplasm
    Organelles
  • 17. AnimalCell
  • 18. Plant Cell
  • 19. Membrane
    Separates the cell from the environment.
    Boundary layer for regulating the movement of materials in/out of a cell.
  • 20.
  • 21. Cytoplasm
    Cell substance between the cell membrane and the nucleus.
    The “fluid” part of a cell. Exists in two forms:
    gel - thick
    sol - fluid
  • 22. Organelle
    Term means "small organ” Formed body in a cell with a specialized function.
    Important in organizational structure of cells.
  • 23. Organelles - function
    Way to form compartments in cells to separate chemical reactions.
    Keeps various enzymes separated in space.
  • 24. Nucleus
    Most conspicuous organelle.
    usually spherical, but can be lobed or irregular in shape.
  • 25. Structure
    Nuclear membrane
    Nuclear pores
    Nucleolus
    Chromatin
  • 26.
  • 27. Nuclear Membrane
    Double membrane separated by a 20-40 nm space.
    Inner membrane supported by a protein matrix which gives the shape to the nucleus.
  • 28. Nuclear Pores
    Regular “holes” through both membranes.
    100 nm in diameter.
    Protein complex gives shape.
    Allows materials in/out of nucleus.
  • 29. Nucleolus
    Dark staining area in the nucleus.
    0 - 4 per nucleus.
    Storage area for ribosomes.
  • 30. Chromatin
    Chrom: colored
    - tin: threads
    DNA and Protein in a “loose” format. Will form the cell’s chromosomes.
  • 31. Nucleus - Function
    Control center for the cell.
    Contains the genetic instructions.
  • 32. Ribosomes
    Structure: 2 subunits made of protein and rRNA.
    No membrane.
    Function: protein synthesis.
  • 33.
  • 34. Locations
    Free in the cytoplasm - make proteins for use in cytosol.
    Membrane bound - make proteins that are exported from the cell.
  • 35. Endomembrane System
    Membranes that are related through direct physical continuity or by the transfer of membrane segments called vesicles.
  • 36. Endomembrane System
  • 37. Endoplasmic Reticulum
    Often referred to as ER.
    Makes up to 1/2 of the total membrane in cells.
    Often continuous with the nuclear membrane.
  • 38.
  • 39. Structure of ER
    Folded sheets or tubes of membranes.
    Very “fluid” in structure with the membranes constantly changing size and shape.
  • 40. Types of ER
    Smooth ER: no ribosomes.
    Used for lipid synthesis, carbohydrate storage, detoxification of poisons.
    Rough ER: with ribosomes.
    Makes secretory proteins.
  • 41. Golgi Apparatus
    Structure: parallel array of flattened cisternae. (looks like a stack of Pita bread)
    3 to 20 per cell.
    Likely an outgrowth of the ER system.
  • 42.
  • 43. Function of Golgi Bodies
    Processing - modification of ER products.
    Distribution - packaging of ER products for transport.
  • 44. Golgi Vesicles
    Small sacs of membranes that bud off the Golgi Body.
    Transportation vehicle for the modified ER products.
  • 45. Cell-On-The-Ceiling Project
  • 46.
  • 47.
  • 48.
  • 49. Lysosome
    Single membrane.
    Made from the Golgi apparatus.
  • 50. Function
    Breakdown and degradation of cellular materials.
    Contains enzymes for fats, proteins, polysaccharides, and nucleic acids.
    Over 40 types known.
  • 51.
  • 52.
  • 53. Lysosomes
    Important in cell death.
    Missing enzymes may cause various genetic enzyme diseases.
  • 54. Vacuoles
    Structure - single membrane, usually larger than the Golgi vesicles.
    Function - depends on the organism.
  • 55. Protists
    Contractile vacuoles - pump out excess water.
    Food vacuoles - store newly ingested food until the lysosomes can digest it.
  • 56.
  • 57. Plants
    Large single vacuole when mature making up to 90% of the cell's volume.
    Tonoplast - the name for the vacuole membrane.
  • 58.
  • 59. Function
    Water regulation.
    Storage of ions.
    Storage of hydrophilic pigments. (e.g. red and blues in flower petals).
  • 60. Function: Plant vacuole
    Used to enlarge cells and create turgor pressure.
    Enzymes (various types).
    Store toxins.
    Coloration.
  • 61. Microbodies
    Structure: single membrane.
    Often have a granular or crystalline core of enzymes.
  • 62. Function
    Specialized enzymes for specific reactions.
    Peroxisomes: use up hydrogen peroxide.
    Glyoxysomes: lipid digestion.
  • 63. Enzymes in a crystal
  • 64. Mitochondria
    Structure: 2 membranes. The inner membrane has more surface area than the outer membrane.
    Matrix: inner space.
    Intermembrane space: area between the membranes.
  • 65.
  • 66. Inner Membrane
    Folded into cristae.
    Amount of folding depends on the level of cell activity.
    Contains many enzymes.
    ATP generated here.
  • 67. Function
    Cell Respiration - the release of energy from food.
    Major location of ATP generation.
    “Powerhouse” of the cell.
  • 68. Mitochondria
    Have ribosomes.
    Have their own DNA.
    Can reproduce themselves.
    May have been independent cells at one time.
  • 69. Chloroplasts
    Structure - two outer membranes.
    Complex internal membrane.
    Fluid-like stroma is around the internal membranes.
  • 70.
  • 71. Inner or Thylakoid Membranes
    Arranged into flattened sacs called thylakoids.
    Some regions stacked into layers called grana.
    Contain the green pigment chlorophyll.
  • 72. Function
    Photosynthesis - the use of light energy to make food.
  • 73. Chloroplasts
    Contain ribosomes.
    Contain DNA.
    Can reproduce themselves.
    Often contain starch.
    May have been independent cells at one time.
  • 74. Plastids
    Group of plant organelles.
    Structure - single membrane.
    Function - store various materials.
  • 75. Cytoskeleton
    Network of rods and filaments in the cytoplasm.
  • 76.
  • 77. Functions
    Cell structure and shape.
    Cell movement.
    Cell division - helps build cell walls and move the chromosomes apart.
  • 78. Components
    Microtubules
    Microfilaments
    Intermediate Filaments
  • 79.
  • 80. Microtubules
    Structure - small hollow tubes made of repeating units of a protein dimer.
    Size - 25 nm diameter with a 15 nm lumen. Can be 200 nm to 25 mm in length.
  • 81. Tubulin
    Protein in microtubules.
  • 82. Microtubules
    Regulate cell shape.
    Coordinate direction of cellulose fibers in cell wall formation.
    Tracks for motor molecules.
  • 83. Microtubules
    Form cilia and flagella.
    Internal cellular movement.
    Make up centioles, basal bodies and spindle fibers.
  • 84. Cilia and Flagella
    Cilia - short, but numerous.
    Flagella - long, but few.
    Function - to move cells or to sweep materials past a cell.
  • 85. Movie
  • 86.
  • 87. Centrioles
    Usually one pair per cell, located close to the nucleus.
    Found in animal cells.
    9 sets of triplet microtubules.
    Help in cell division.
  • 88. Basal Bodies
    Same structure as a centriole.
    Anchor cilia and flagella.
  • 89. Microfilaments
    5 to 7 nm in diameter.
    Structure - two intertwined strands of actin protein.
  • 90.
  • 91.
  • 92. Microfilaments are stained green.
  • 93. Functions
    Muscle contraction.
    Cytoplasmic streaming.
    Pseudopodia.
    Cleavage furrow formation.
    Maintenance and changes in cell shape.
  • 94. Intermediate Filaments
    Fibrous proteins that are super coiled into thicker cables and filaments 8 - 12 nm in diameter.
    Made from several different types of protein.
  • 95.
  • 96. Functions
    Maintenance of cell shape.
    Hold organelles in place.
  • 97. Cytoskeleton
    Very dynamic; changing in composition and shape frequently.
    Cell is not just a "bag" of cytoplasm within a cell membrane.
  • 98. Cell Wall
    Nonliving jacket that surrounds some cells.
    Found in:
    Plants
    Prokaryotes
    Fungi
    Some Protists
  • 99. Plant Cell Walls
    All plant cells have a Primary Cell Wall.
    Some cells will develop a Secondary Cell Wall.
  • 100.
  • 101. Primary Wall
    Thin and flexible.
    Cellulose fibers placed at right angles to expansion.
    Placement of fibers guided by microtubules.
  • 102. Secondary Wall
    Thick and rigid.
    Added between the cell membrane and the primary cell wall in laminated layers.
    May cover only part of the cell; giving spirals.
    Makes up "wood”.
  • 103. Middle Lamella
    Thin layer rich in pectin found between adjacent plant cells.
    Glues cells together.
  • 104. Cell Walls
    May be made of other types of polysaccharides and/or silica.
    Function as the cell's exoskeleton for support and protection.
  • 105. Extracellular Matrix - ECM
    Fuzzy coat on animal cells.
    Helps glue cells together.
    Made of glycoproteins and collagen.
    Evidence suggests ECM is involved with cell behavior and cell communication.
  • 106.
  • 107. Intercellular Juctions
    Plants-Plasmodesmata
  • 108. Plasmodesmata
    Channels between cells through adjacent cell walls.
    Allows communication between cells.
    Also allows viruses to travel rapidly between cells.
  • 109.
  • 110. Intercellular Juctions
    Animals:
    Tight junctions
    Desmosomes
    Gap junctions
  • 111.
  • 112. Tight Junctions
    Very tight fusion of the membranes of adjacent cells.
    Seals off areas between the cells.
    Prevents movement of materials around cells.
  • 113. Desmosomes
    Bundles of filaments which anchor junctions between cells.
    Does not close off the area between adjacent cells.
    Coordination of movement between groups of cells.
  • 114. Gap Junctions
    Open channels between cells, similar to plasmodesmata.
    Allows “communication” between cells.

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