The two amino acids shown above are joined together by a peptide bond and form a molecule of which of the following in the process?

• A. Carbon dioxide (CO\(_2\))
• B. Oxygen (O\(_2\))
• C. Ammonia (NH\(_3\))
• D. Water (H\(_2\)O)

Answer: (D)

Verified step by step guidance

1. Understand the process of peptide bond formation: A peptide bond is formed between the carboxyl group (-COOH) of one amino acid and the amino group (-NH\(_2\)) of another amino acid during a condensation reaction.
2. Recognize that a condensation reaction involves the removal of a small molecule, typically water (H\(_2\)O), as the bond is formed.
3. Visualize the chemical reaction: The hydroxyl group (-OH) from the carboxyl group of one amino acid combines with a hydrogen atom (H) from the amino group of the second amino acid to form water (H\(_2\)O).
4. Write the general chemical equation for peptide bond formation: Amino acid 1 + Amino acid 2 → Dipeptide + H\(_2\)O.
5. Conclude that the molecule released during peptide bond formation is water (H\(_2\)O), as this is a characteristic of condensation reactions in biochemistry.