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Transmission Electron Microscope

The transmission electron microscope passes a beam of electrons through a thin specimen and focuses the electrons that have passed through the specimen onto a screen to form a two-dimensional image. It has a resolution of 0.5nm.
The specimen is prepared by
  • fixing (cross-linking) the proteins with aldehyde
  • fixing lipids such as the cell membranes with a substance that forms a black insoluble precipitate on the lipid for contrast
  • adding heavy metal salts for additional contrast
  • dehydrating the specimen with ethanol
  • embedding in resin and curing into a hard block using heat or UV light
  • sectioning into thin slice
The process can be automated.

Read the text

Read the text and highlight anything you think is important. When you go on, the text is hidden and you answer from memory.

Specification: OCR Biology A (H020), AS-level, 2.1.1 Cell structure. Topic: Components of Living Systems.

Key terms in this lesson

resolution
The ability to distinguish two objects that are close together as separate entities, which determines how much detail can be seen.

More in Components of Living Systems

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