Posters

Question 1

Explain twinning

Answer 1

Twinning is when two or more crystal domains grow together in a fixed geometric relationship, causing their diffraction patterns to overlap.

Why it matters / useful:
- Can help crystals form when single crystals won’t
- Sometimes gives better diffraction due to symmetry operations

Question 2

Explain omit maps

Answer 2

An electron-density map made after removing a part of the model density (like a residue or ligand).

Why we use it:
To avoid model bias
To confirm if a ligand or region is really there or if it was just from the model
To validate weak or uncertain density

If the omitted feature still appears in the map → the data truly supports it and it’s not just from the model

Question 3

Explain anisotropic diffraction

Answer 3

When a crystal diffracts differently in different directions — some directions give strong reflections, others weaker.

Why it matters:
Indicates the crystal isn’t equally ordered in all directions
Affects map quality and resolution
Needs corrections (like anisotropic B-factor correction) to improve refinement and produce accurate electron-density maps