Microscopy

• Microscopy


  The study of objects using a microscope
• Microscopes are important for biology
• Cells are studied using microscopes


  Microscopes let us see things we can't see with the naked eye
• Light microscopes


  • Use light and lenses to form an image of a specimen and magnify it
  • Let us see individual cells and large subcellular structures like nuclei
• Electron microscopes


  • Use electrons instead of light to form an image
  • Have a much higher magnification than light microscopes
  • Have higher resolution (ability to distinguish between points for a sharper image)
• Electron microscopes


  • Let us see much smaller things in more detail, like the internal structure of mitochondria and chloroplasts, as well as ribosomes and plasmids
• Magnification


  The ratio of the image size to the real size of an object
• Calculating magnification


  Use the formula: magnification = image size / real size
• Standard form


  A way to write very big or small numbers with lots of zeros in a more manageable way, e.g. 0.017 can be written as 1.7 x 10^-2
• Preparing a slide


  1. Add a drop of water to a clean slide

  2. Place a small piece of onion epidermis in the water

  3. Add a drop of iodine stain

  4. Carefully place a coverslip over the specimen
• Using a light microscope

  1. Clip the slide onto the stage

  2. Select the lowest-powered objective lens

  3. Use the coarse adjustment to bring the stage close to the lens

  4. Look through the eyepiece and use the fine adjustment to focus the image
• Draw observations neatly with a pencil
• Include a title, magnification, and label important features in the drawing