Final answer:
Peptide bonds connect the carboxyl group (C=O) of one amino acid to the amino group (N-H) of another amino acid.
Step-by-step explanation:
A. C=O to N-H. Peptide bonds connect the carboxyl group (C=O) of one amino acid to the amino group (N-H) of another amino acid. This reaction releases a molecule of water and forms an amide linkage.