Which of the following shows linear sequence of atoms joined by covalent bonds in peptide backbone.

Question

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

The answer is a). Is that because it's the only one that linear; as in it doesn't have any oxygens or hydrogens coming off of it? I don't exactly know why a) is correct b/c I thought that peptide bond is formed by condensation reaction in which you would have N-C which all options have.

Answer 1

you missed the point of a peptide bond. 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+.

Answer 2

Thank you!