Final answer:
A molecule formed by amino acids linked together through peptide bonds is known as a polypeptide, which becomes a protein when it adopts a specific functional shape.
Step-by-step explanation:
When amino acids are linked together to form chains, the resulting molecule is called a polypeptide. Amino acids bond through a process known as dehydration synthesis, where the carboxyl group of one amino acid reacts with the amino group of another, forming a covalent bond called a peptide bond and a molecule of water as a byproduct. The chain formed by this process can be a dipeptide, tripeptide, oligopeptide, or, when many amino acids are involved, a polypeptide. Once the polypeptide chain folds into a specific three-dimensional structure and functions in the body, it is considered a protein.