What are amino acids primarily used for in cells?

Amino acids are essential molecules in biological systems, serving primarily as the building blocks of proteins. Each amino acid contains an amino group, a carboxyl group, and a unique side chain that defines its properties. When amino acids are linked together through peptide bonds, they form polypeptides, which then fold into functional proteins. Proteins play a critical role in various cellular functions, including catalysis (as enzymes), structural support, transport, cell signaling, and immune responses.

While amino acids can also serve other roles, such as precursors to neurotransmitters and hormones, their primary and fundamental role in the cell is in protein synthesis. The significance of amino acids as protein components underscores their central role in the structure and function of living organisms. Other options focus on processes (like genetic information storage, energy production, or photosynthesis initiation) that are not directly related to the primary function of amino acids.