EMQ 1. Theme: Microscopy

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From the options below, identify the type of microscope most suitable for each of the imaging tasks described in the list.

A Bright field light microscopy
B Fluorescence light microscopy
C Phase contrast microscopy
D Scanning electron microscopy
E Transmission electron microscopy

1. Examine fixed tissue that has been stained with colored dyes. For example, initial studies of tissue biopsies by pathologists use a hematoxylin/eosin mixture, which stains nuclei blue and cytoplasm various shades of pink and red.
Your Answer:
Answer: A, bright field light microscopy. See book page 2. The Wellcome Trust image bank has several nice examples: go to http://images.wellcome.ac.uk/ and search on hematoxylin or eosin.
2. Follow the locomotion of cells (e.g. neutrophils from a patient) that have not been stained or transfected.
Your Answer:
Answer: C, phase contrast light microscopy. Since the cells are neither stained with a dye nor engineered to express a fluorescent protein, they have little color and will not fluoresce. Phase contrast microscopy can, nevertheless, image differences in refractive index, revealing the cells as they move. Figure 1.5 on book page 5 shows an example.
3. Follow the translocation of a chimaeric protein within a living cell.
Your Answer:
Answer: B, fluorescence light microscopy. See book page 115. Fluorescence light microscopy is described in more detail in In Depth 1.1 on book page 6.
4. Generate an impression of the three-dimensional shape of the cell surface, for example of a ciliated epithelial cell.
Your Answer:
Answer: D, scanning electron microscopy. Figure 1.8 on book page 9 shows an example.
5. Reveal the detailed shape and organization of the structures within the centrosome.
Your Answer:
Answer: E, transmission electron microscopy. The centrosome, whose structure is described on book page 283, is too small to be imaged as anything other than a dot by light microscopy.
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