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mcb104 handout week 6

mcb104 handout week 6 - L ectures 14 15 T ypes of...

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Lectures 14 & 15 Types of illumination in microscopy (examples are of blood cells) Bright field: Shine light from above. You can see stained structures or other things that absorb light. Phase contrast: Detects changes in the phase/speed of light passing though cells due to a changing refractive index Dark field: Shine light from the side. You see structures that refract light. Everything else looks black. Differential Interference Contrast (DIC): Similar to phase contrast, but DIC uses polarized light. To make blurry images clearer, we can use deconvolution. For very small objects or much better resolution, we can use electron microscopy. Fluorescence microscopy and GFP : We can fluorescently label individual molecules in a cell using chemicals (fluorophores), antibodies, or fluorescent proteins. In fluorescence microscopy, we excite fluorescent molecules with light at one wavelength and they emit light at a longer wavelength. The difference between excitation and emission wavelengths is called the Stokes shift. GFP can be used to tag a protein of interest to determine its subcellular localization in a living cell or organism. GFP can also be used as a marker for gene expression, by putting the expression of a gene encoding GFP under the same transcriptional regulation of the gene of interest.
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