Electron microscopy

• What should you be able to describe by the end of the video?

  Principles of electron microscopy
• What are the advantages of electron microscopy?

  Higher resolution than light microscopy
• What are the disadvantages of electron microscopy?

  Cannot view living specimens
• How does transmission electron microscopy differ from scanning electron microscopy?

  TEM produces 2D images, SEM produces 3D images
• What is a key benefit of light microscopy?

  Visualizing living cells
• What is the maximum resolution of a conventional light microscope?

  200 nanometers
• What is resolution in microscopy?

  Minimum distance between two distinguishable objects
• How do laser scanning confocal microscopes improve resolution?

  By visualizing a narrow region of the sample
• What is the resolution of an electron microscope compared to a light microscope?

  2000 times better than a light microscope
• What is the wavelength of electrons compared to light?

  Electrons have a very short wavelength
• What is the role of the electron gun in an electron microscope?

  Produces a beam of electrons
• Why is a vacuum necessary in an electron microscope?

  To prevent electrons from bouncing off air molecules
• How are electrons focused in an electron microscope?

  Using electromagnetic lenses
• What happens to electrons when they pass through the specimen?

  They pass through some parts more easily
• Where is the final image produced in an electron microscope?

  On a fluorescent screen
• What is the resolution of an electron microscope under good conditions?

  Up to 0.1 nanometers
• What major discoveries have been made using electron microscopy?

  Ribosomes and cell membrane structure
• What is a disadvantage of electron microscopy regarding specimen preparation?

  Requires careful staining and thin slicing
• What are artifacts in electron microscopy?

  False images created by staining or conditions
• What is the difference in specimen requirements between TEM and SEM?

  TEM requires thin specimens, SEM does not
• What type of images does a transmission electron microscope produce?

  Flat two-dimensional images
• How does a scanning electron microscope produce images?

  By scattering electrons from the surface
• What type of images does a scanning electron microscope produce?

  Three-dimensional images
• What is required for a specimen in a scanning electron microscope?

  Coated with a metal like gold
• What can lead to artifacts in scanning electron microscopy?

  Coating the specimen with metal
• What are the principles of electron microscopy?

  • Uses electrons instead of light
  • Electrons have a short wavelength
  • Produces high-resolution images
  • Can visualize structures at nanometer scale
• Compare transmission electron microscopy (TEM) and scanning electron microscopy (SEM).

  **Transmission Electron Microscopy (TEM):**

  • Produces flat 2D images
  • Requires thin specimens
  • High resolution

  
  

  **Scanning Electron Microscopy (SEM):**

  • Produces 3D images
  • Does not require thin specimens
  • Lower resolution than TEM