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THE TOUR OF THE CELL

THE TOUR OF THE CELL. CHAPTER 4. Cell Theory. 1) Every organism is composed of one or more cells 2) Cell is smallest unit having properties of life (movement, respiration, sensitivity, growth, reproduction, excretion & nutrition). 3) All cells come from other cells.

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THE TOUR OF THE CELL

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  1. THE TOUR OF THE CELL CHAPTER 4

  2. Cell Theory 1) Every organism is composed of one or more cells 2) Cell is smallest unit having properties of life (movement, respiration, sensitivity, growth, reproduction, excretion & nutrition). 3) All cells come from other cells.

  3. Basic Aspects of Cell Structure & Function • The cell: • Smallest unit of life • Can survive on its own or has potential to do so • Is highly organized for metabolism • Senses and responds to environment • Has potential to reproduce

  4. Structure of Cell All start out life with: • Plasma membrane • Region where DNA is stored • Cytoplasm Two types: • Prokaryotic • Eukaryotic

  5. Fluid Mosaic Model of Cell Membrane (Phospholipid Bilayer) • Main component of cell membranes • Gives the membrane its fluid properties • Two layers of phospholipids

  6. Phospholipid Bilayer

  7. Fluid Mosaic Model • Membrane is a mosaic of • Phospholipids • Glycolipids • Sterols • Proteins • Most phospholipids and some proteins can drift through membrane

  8. Fluid Mosaic Model EXTRACELLULAR ENVIRONMENT CYTOPLASM

  9. Cell Size & Shape • Why Are Cells So Small? • Surface-to-volume ratio • The bigger a cell is, the less surface area there is per unit volume • Above a certain size, material cannot be moved in or out of cell fast enough

  10. Defining Features of Eukaryotic Cells • Have a nucleus and other membrane bound organelles • Eukaryotic organisms • Plants • Animals • Protistans • Fungi

  11. Plasma membrane Nucleus Ribosomes Endoplasmic reticulum Golgi body Vesicles Mitochondria Cytoskeleton Animal Cell Features

  12. Animal Cell

  13. Plasma membrane Nucleus Ribosomes Endoplasmic reticulum Golgi body Cell wall Chloroplast Central Vacuole Vesicles Mitochondria Cytoskeleton Plant Cell Features

  14. The Nucleus • Keeps the DNA molecules of eukaryotic cells separated from metabolic machinery of cytoplasm • Makes it easier to organize DNA and to copy it before parent cells divide into daughter cells

  15. Components of Nucleus • Nuclear envelope • Nucleoplasm • Nucleolus • Chromosome • Chromatin

  16. Nuclear Envelope • Two outer membranes (lipid bilayers) • Pores span bilayer

  17. Nucleolus • Cluster of DNA and proteins • Materials from which ribosomal subunits are built • Subunits must pass through nuclear pores to reach cytoplasm

  18. Chromatin • Cell’s collection of DNA and associated proteins • Chromosome is one DNA molecule and its associated proteins • Appearance changes as cell divides

  19. The Endomembrane System • Group of related organelles in which lipids are assembled and new polypeptide chains are modified • Products are sorted and shipped to various destinations

  20. Endoplasmic Reticulum (ER) • In animal cells, continuous with nuclear membrane • Extends throughout cytoplasm • Two regions - rough and smooth • Protein synthesis (RER), Lipid synthesis (SER)

  21. Mitochondria • ATP-producing powerhouses • Double-membrane system • Carry out the most efficient energy-releasing reactions • These reactions require oxygen

  22. Specialized Plant Organelles • Central Vacuole • Chloroplasts

  23. Central Vacuole • Fluid-filled organelle • Stores amino acids, sugars, wastes • As cell grows, vacuole expands as a result of fluid pressure forces cell wall to expand • In mature cell, central vacuole takes up 50-90 percent of cell interior

  24. Chloroplasts Convert sunlight energy to ATP through photosynthesis

  25. The Cytoskeleton • Present in all eukaryotic cells • Basis for cell shape and internal organization • Allows organelle movement within cells and, in some cases, cell movement

  26. Components of Cytoskeleton intermediate filament microtubule microfilament

  27. Mechanisms of Movement • Length of microtubules or microfilaments can change • Parallel rows of microtubules or microfilaments actively slide in a specific direction • Microtubules or microfilaments can move organelles to different parts of cell

  28. Flagella and Cilia • Structures for cell motility • 9 + 2 internal structure Microtubule doublet Dynein arm

  29. Cell Surface Specializations & Junctions • Cell wall • Structural component that wraps around the plasma membrane • Occurs in plants, some fungi, some protistans

  30. Cell Junctions • Plants • Plasmodesmata • Animals • Tight junctions • Adhering junctions • Gap junctions

  31. Animal Cell Junctions Tight junctions Gap junction Adhering junction

  32. Prokaryotic Cells • Archaebacteria and Eubacteria • DNA is NOT enclosed in nucleus • Generally the smallest, simplest cells • No organelles

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