BLG 311 Lecture Notes - Lecture 2: Macromolecule, Glutaraldehyde, Scanning Electron Microscope
29 Dec 2017
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Has a higher resolution that light microscopy. Tem allows you to transmit electrons through the sample. Condenser lens is a magnet in the em, not something that focuses light rays, but focuses. Some electrons will pass through the sample, some electrons will be reflected back, and some electrons will bounce on heavy metals and go somewhere else. The sample is bright against a dark background. Projector lens is also an electromagnet able to focus. You cannot use live cells with tem because you are not actually imagining the cell itself you are imaging a cast. The cast/replica is made out of metal because cells are usually deficient in heavy metals which help electrons pass through or bounce off of the sample so you can see it. Resolution is much better in tem than light microscopy because electrons have a different wavelength than light. 1 nm is the resolution for biological samples. 0. 002 nm is the resolution limit for inorganic samples.
