Question

question 5
which of the following statements about peptides is correct?
a peptide bond is formed by a condensation reaction between the carboxyl and amino group of the same amino acid.
the peptide bond is capable of rotating.
a peptide bond is formed by a condensation reaction between two carboxyl groups.
as a whole, the structure of the peptide - bonded backbone is flexible.
joining two amino acids together through a peptide bond results in the formation of a carboxyl group.

Explanation:

A peptide bond is formed by a condensation reaction between the carboxyl group of one amino - acid and the amino group of another amino - acid, not the same one or two carboxyl groups. The peptide bond has partial double - bond character and is relatively rigid and does not rotate freely. When two amino acids are joined by a peptide bond, a water molecule is released, not a carboxyl group. The peptide - bonded backbone has some flexibility due to the rotation around the single bonds in the backbone.

Answer:

D. As a whole, the structure of the peptide - bonded backbone is flexible.