Answer:
The correct answer is 23.
Explanation:
Beta sheets are a kind of secondary composition in proteins, which are formed of the beta-strands that are associated laterally by more than two hydrogen bonds. A beta chain or strand comprises three to ten amino acid residues.
One is familiar by the fact that in case of an anti-parallel combination after every 7 angstroms there is a repeat, and per each repeat, there are 2 residues. Thus, after every 7 angstroms, 2 residues are present.
In the given question, length of the antiparallel beta-sheet is 80.5 Angstrom = (number of segments) * (residues per segment)
= (80.5/7)*2
= 11.5*2
= 23
Hence, the number of residues in the given segment is 23.
