BIOL 2021 Chapter Notes - Chapter 2.2: Transmission Electron Microscopy, Scanning Electron Microscope, Electron Microscope
2 Apr 2018
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An electron microscope is used to resolve objects smaller than light microscopes can (1nm) Wavelength of electrons is shorter than light. Can get down to the molecular level (proteins, small molecules, atoms) Transmission em: uses an electron gun to shoot electrons at the specimen of interest. Specimen must be in thin slices so that electrons can travel. Material (heavy metals) so that they can absorb/block the electrons. Electrons pass through the specimen and the stained areas will look dark since no electrons pass through. Scanning em: directly produces an image of the 3d structure of the surface of a specimen. Electrons are scattered/emitted from the surface of the specimen, instead of going through it. The specimen must be fixed, dried, and coated with a thin layer of heavy metal. Of the specimen usually used to observe the outside of full animal or plant cells or tissues.
