Proteins are primarily composed of which of the following?

Proteins are primarily composed of amino acids, which are the building blocks of protein structures. These amino acids link together in various sequences to form polypeptides, which then fold into specific three-dimensional shapes to produce functional proteins. Each protein has a unique sequence and combination of amino acids that determine its specific function within the body.

Amino acids play crucial roles in numerous biological processes, including catalytic functions as enzymes, structural roles in cells, and participation in signaling pathways. The sequence of amino acids in a protein is dictated by the genetic information encoded in an organism's DNA, and the correct assembly of these amino acids is essential for the proper functioning of proteins.

The other options, such as carbohydrates, fatty acids, and nucleic acids, are completely different macromolecules with distinct roles in biology. Carbohydrates serve primarily as energy sources or structural components, fatty acids are involved in lipid formation and energy storage, and nucleic acids are responsible for storing and transmitting genetic information. Thus, the focus on amino acids as the main components of proteins is critical to understanding protein composition and function.