Question

Arrange the following X-ray crystallography workflow sequence: A. Record diffraction images, B. Build atomic model, C. Grow a crystal, D. Mount crystal and expose to X-rays, E. Solve phases and compute electron density.

• A. A, C, E, D, B
• B. A, C, B, D, E
• C. C, D, A, E, B
• D. C, A, D, B, E

Hint:

X-ray crystallography sequence: grow crystal, expose to X-rays, record diffraction, calculate electron density, and build atomic model.

Answer 1

The Correct Option is C

Concept:
X-ray crystallography is used to determine the three-dimensional atomic structure of molecules, especially proteins and other biomolecules.

Step 1: Grow a crystal.
The first requirement is a good-quality crystal of the molecule. \[ \text{First step} = C \]

Step 2: Mount the crystal and expose it to X-rays.
The crystal is mounted and placed in the X-ray beam. \[ \text{Second step} = D \]

Step 3: Record diffraction images.
When X-rays interact with the crystal, diffraction patterns are produced and recorded. \[ \text{Third step} = A \]

Step 4: Solve phases and compute electron density.
Diffraction intensities are used to calculate electron density maps after phase determination. \[ \text{Fourth step} = E \]

Step 5: Build atomic model.
Finally, the atomic model is fitted into the electron density map. \[ \text{Fifth step} = B \] Thus, the correct sequence is: \[ C,\ D,\ A,\ E,\ B \] \[ \therefore \text{Correct Answer is (C)} \]