microscopes

• Microscopy


  The use of microscopes to study things that cannot be seen with the naked eye
• Cells are studied using microscopes
• Microscopes


  • Let us see things that we can't see with the naked eye
  • Microscopy techniques have developed over the years as technology and knowledge have improved
• 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 a higher resolution (ability to distinguish between two points, so a higher resolution gives a sharper image)
• Electron microscopes


  • Let us see much smaller things in more detail, like the internal structure of mitochondria and chloroplasts
  • Let us see tinier things like ribosomes and plasmids
• Using the formula for magnification


  1. Magnification = image size / real size

  2. If the units are different, need to convert them first
• Calculating magnification


  • A specimen is 50 μm wide, calculate the width of the image under 100x magnification
• Standard form


  • Writing very big or small numbers with lots of zeros in a more manageable way, e.g. 0.017 can be written 1.7 x 10-2
  • The number of places the decimal point moves is represented by a power of 10 - positive if moved left, negative if moved right
• Writing a number in standard form

  • A mitochondrion is approximately 0.0025 mm long, written in standard form is 2.5 x 10-3
• Solving a magnification problem

  1. Rearrange the magnification formula

  2. Fill in the known values

  3. Remember the units

  4. Convert the units if needed