Which of the following shows linear sequence of atoms joined by covalent bonds in peptide backbone.
(A) -N-C-C-N-C-C-N
(B) -N-C-O-N-C-O-
(C) -N-C-C-O-N-C-C-O
(D)-N-H-C-C-N-H-C-C
Correct option is (A) -N-C-C-N-C-C-N. Explanation: it's the only one that linear; as in it doesn't have any oxygens or hydrogens coming off of it? Peptide bond is when a carboxyl connects to a N. -C(O)-N- where the O is a double bonded O to the C.a is the only one in which the backbone is shown as a peptide. Yes, I object to the "backbone" also, as it misses the point of the carboxyl C. I rate the question no better than a C+.