Final answer:
A protein is composed of many amino acids, arranged in chains known as polypeptides, and determines the structure and function of the protein.
Step-by-step explanation:
A protein is made of many amino acids. Proteins are essential organic compounds composed of amino acids arranged in one or more long chains called polypeptides. The sequence and number of amino acids determine the protein's structure and function. With 20 different standard amino acids found in nature, there can be thousands of different protein combinations. A single protein molecule may be made up of anywhere from just a few hundred to over 25,000 amino acids. In muscle tissue, for instance, the large protein titin is comprised of more than 27,000 amino acids.