Feedback for Multiple Choice Quiz 21

  1. The key word in the question is "calculated directly". The coordinates and the size of the protein are derived from the interpretation of the electron densities. The latter allows one to propose a model of the structure.

  2. Each atom acts as a source of scattered X-rays. Leading to both constructive and destructive interference as these X-rays add at the detector (film).

  3. X-rays are diffracted by electrons: the greater the electron density, the greater the signal.
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