A length of ten amino acid residues in a protein is involved in some type of secondary structure. What are the various types of secondary structure that this length of residues could be involved in? Rank these types of structure in terms of length (longest to shortest). Then separately rank them according to stability (most stable to least stable).
Length: β-pleated sheet is clearly the longest. Hard to know how the reverse turn compares to the compact α-helix, since we do not know what the other six residues in the reverse turn are doing. (WHAT DO THEY MEAN BY THE OTHER SIX? WHAT HAPPENED TO THE FIRST 4?)
Stability: β-pleated sheets > α-helix > reverse turn (where > means "more stable") (WHY???)