Microscopes

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  • Microscopes
    • Magnification/ resolution
      • Magnification= Image size\Actual size
      • Resolution: how well microscope distinguishes between two objects close together
    • Optical (light) microscope
      • Use light to form image
      • Max resolution of 0.2 micrometers
      • Can't see ribosomes, ER, lysosomes
      • Magnification of x1500
      • Cheap, easy to use, portable
    • TEM
      • Use electromagnets to focus beam of electrons which is transmitted through specimen
      • Denser parts of specimen absorb more electrons and look darker
      • High resolution images, can see internal structure of organelles
      • Can only be used on thin specimens
    • SEM
      • Scan a beam of electrons across specimen, Knocks off electrons from specimen
      • Images show surface of specimen, can be 3D
      • Can be used on thick specimens, lower resolution images
      • Large, very expensive, need skill and training to use
        • TEM
          • Use electromagnets to focus beam of electrons which is transmitted through specimen
          • Denser parts of specimen absorb more electrons and look darker
          • High resolution images, can see internal structure of organelles
          • Can only be used on thin specimens
    • Preparing a slide
      • 1: Pipette a small drop of water onto a slide. Use tweezers to place thin section of specimen on top of water
      • 2: Add a drop of stain to highlight objects in cell
      • 3: Add cover slip to slide
    • Laser Scanning Microscopes
      • use laser light to scan object point by point and assemble image by computer
      • Images high resolution and high contrast
      • Depth selectivity- can focus on structures at different depths within specimen, can be used to observe whole specimens as well as cells
      • Used in medical profession to give swift diagnosis and more effective treatment. Also used in biological research

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