Cells

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  • Created by: emma
  • Created on: 17-04-14 15:23
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  • Cells
    • Organelles in eukaryotic cells
      • Nucleus- contains genetic information (DNA), controls cell
      • Mitochondria- site of ATP production from aerobic respiration, double membrane  cristae and matrix
      • Rough endoplasmic reticulum- Transports proteins through cell, has ribosomes
      • Smooth endoplasmic reticulum- synthesis of lipids, doesn't have ribosomes
      • Golgi apparatus- sorts, processes and packages proteins, can form lysosomes
      • Ribosomes- protein synthesis
      • Lysosomes- Contain digestive enzymes and break down unwanted structures
      • Microvili- increase surface area of cell
      • Cell membrane- controls passage of molecules in and out of cell
    • Prokaryotic cell
      • DNA circular, not associated with proteins
        • Contain no membrane bound organelles
          • Has no nucleus
            • Contains 70s ribosomes
              • Has a capsule, flagella
    • Eukaryotic cell
      • DNA linear, associated with proteins
        • contain membrane bound organelles, mitochondria, golgi
          • Has a nucleus
            • Contains 80s ribosomes
              • Don't have capsule, flagella
    • Microscopes
      • Resolution- the ability to distinguish between objects that are close together
        • Electron microscopes have better resolution than light microscopes as they have shorter wavelenghts
      • Light microscope
        • Low resolution but produces colour image, specimens can be alive, low cost
      • Electron microscope
        • High resolution but specimens must be dead, black and white image only, high cost
        • SEM
          • Produce 3D image but lower resolution
        • TEM
          • Produc 2D image but higher resolution
      • Image size= Magnification * object size
    • Cell fractionation
      • 1)Homogenised to release cell oragnelles
        • In an ice cold, isotonic buffered solution
          • ice cold- reduce enzyme activity
          • Isotonic- stop the net movement of water in and out of organelles to prevent them bursting or shrinking
          • Buffered- stop PH changes that could denature proteins
      • 2) Mixture is filtered to remove cell debris
      • 3)Centrifuged at a low speed so large organelles are forced into pellet at bottom and can be remmoved
        • 4) Centrifuged at a high speed so small organelles are forced into pellet at the bottom and can be removed
  • In an ice cold, isotonic buffered solution
    • ice cold- reduce enzyme activity
    • Isotonic- stop the net movement of water in and out of organelles to prevent them bursting or shrinking
    • Buffered- stop PH changes that could denature proteins

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