Final answer:
In peptide bond formation, the amino group of one amino acid reacts with the carboxyl group of another, creating an amide bond. The polypeptide chain has a directional structure with a free amino group at the N terminal and a free carboxyl group at the C terminal, crucial for protein function.
Step-by-step explanation:
Amino acids are the building blocks of peptides and proteins, linked together by peptide bonds. The groups involved in forming a peptide bond are the amino group (-NH2) from one amino acid and the carboxyl group (-COOH) from another amino acid. During the formation of a peptide bond, these groups combine in a dehydration synthesis reaction, resulting in the release of a molecule of water and the creation of an amide bond between the two amino acids.
The resulting polypeptide chain has a free amino group at the N terminal and a free carboxyl group at the C terminal. This directional structure is important as the sequence of amino acids, which determines the protein's properties, is read from the N terminal to the C terminal. The unique sequence of amino acids is key to the protein's structure and function after it goes through post-translational modifications to become fully functional.