1. PDB entry 1JY4 is a/n ___-stranded b sheet where each strand is arranged in a/n ________ fashion.

• 6; parallel
• 8; antiparallel
• 6; antiparallel
• 8; parallel

2. In a ribbon diagram of the structure of 1JY4, each strand of the b sheet is represented by an arrow that points towards the _____________.

• N-terminus
• C-terminus

3. In 1JY4, the presence of _____ at each turn in the β sheet is _________ with the known properties of the amino acid.

• D-Pro; consistent
• D-Pro; inconsistent
• L-Pro; consistent
• L-Pro; inconsistent

4. PDB entry 2BEG contains a total of 5 oligopeptides; each oligopeptide participates in ___ unique β sheet/s whose strands are arranged in a/n ________ fashion.

• 1; parallel
• 1; antiparallel
• 2; parallel
• 2; antiparallel

5. In 2BEG, the amino acids within each strand of the β sheets ____ sequentially and significantly alternate between polar and nonpolar.

• do
• do not

6. Choose the statement that is consistent with the following rendering of 2BEG: Display the backbone as a "traditional" ribbon for all chains and specifically turn on the visibility for the atoms and bonds of residue D 23 on chain A and residue K 28 on chain B. View this structure in different styles by displaying the atoms of these amino acids in both "small" and "CPK" formats; for comparison, perform the same rendering for the remaining chains.

• The β sheets are stabilized by multiple intrachain ion pairs.
• The β sheets are stabilized by multiple interchain ion pairs.
• The β sheets are stabilized by multiple intrachain hydrogen bonds.
• The β sheets are not stabilized by any intrachain or interchain ion pairs.

7. Does the abstract for PDB entry 2BEG support the presence of intermolecular bonds between side chains?

• Yes
• Now

8. Consider the structure for 4POC. Which of the following conclusions can be made about parallel β sheets in this protein?

• Parallel β sheets are mostly in the protein interior.
• Parallel β sheets are in the protein interior and on the protein exterior.
• Parallel β sheets are never in the protein interior.
• Parallel β sheets are mostly on the protein exterior.

9. Consider the structure for 4M43. Which of the following conclusions can be made about antiparallel β sheets in this protein? Display the backbone as a "traditional" ribbon for all chains and specifically turn on the visibility for the atoms and bonds of residues 69-76 on Chain L.

• Antiparallel β sheets are in the protein interior and on the protein exterior.
• Antiparallel β sheets are mostly in the protein interior.
• Antiparallel β sheets are never on the protein exterior.
• Antiparallel β sheets are mostly on the protein exterior.