1. Which of the following is not a form of secondary structure? Alpha, beta, gamma Phi, psi, omega Phi, psi, omega, chi alpha helix beta strand 310 helix omega helix pi helix
2. Which of the following statements is true? C-N-CA-C CA-C-N-CA N-CA-C-N All secondary structures are always stabilized by hydrogen bonds within the secondary structure element All secondary structures are stabilized by hydrogen bonds
3. Which of the following statements is true? C-N-CA-C CA-C-N-CA N-CA-C-N All secondary structures are long sections of repeating backbone torsion angles Secondary structures vary in length substantially and have repeating backbone torsion angles The backbone torsion angles are identical within a given secondary structure element
4. What is the Ramachandran plot? C-N-CA-C CA-C-N-CA N-CA-C-N A plot of phi angles against psi angles A plot of psi angles against phi angles A plot of psi angles against omega angles A plot of phi angles against chi angles
5. Proline residues are often described as 'helix breakers'. This is because: A single bond A double bond A partial double bond They do not have a sidechain They cannot adopt the phi/psi backbone conformation of an alpha helix They have no backbone hydrogen so cannot form the stabilizing hydrogen bond
6. Proline residues in beta sheets are generally only found in edge strands. This is because: Delocalization of a lone pair of electrons on the carbonyl oxygen resulting in a partial positive charge on the oxygen and a partial negative charge on the backbone nitrogen Delocalization of a lone pair of electrons on the backbone nitrogen resulting in a partial positive charge on the nitrogen and a partial negative charge on the carbonyl oxygen They do not have a sidechain They cannot adopt the phi/psi backbone conformation of a beta strand They have no backbone hydrogen so cannot form the stabilizing hydrogen bond
7. Which of the following statements is true? Close to +/- 90 degrees Close to 90 degrees Close to 180 degrees Close to 0 degrees Freely rotatable None of the above The distribution of phi/psi angles in the Ramachandran plot is not affected by the resolution of the structure Low resolution (less accurate) structures tend to show more outlying phi/psi angles in the Ramachandran plot
8. Which direction corresponds to a positive torsion angle? Moving the near atom anti-clockwise or the distant atom clockwise Moving the near atom clockwise or the distant atom anti-clockwise
9. The peptide bond is often close to 0 degrees when the following amino acid is: Glycine Proline Alanine Tryptophan