What macromolecule contains the principal components of living organisms and serves various structural and regulatory roles?

Proteins are essential macromolecules that play a crucial role in the structure and functioning of living organisms. They are composed of amino acids linked together in specific sequences that dictate their unique three-dimensional structures. This structural diversity allows proteins to perform a wide range of functions, including acting as enzymes to catalyze biochemical reactions, serving as structural components in cells and tissues (collagen in connective tissues, for instance), and functioning in cell signaling and regulatory processes (such as hormones).

Moreover, proteins are integral to various cellular processes, including immune responses and transport mechanisms, further highlighting their importance in both structural and regulatory roles within biological systems. Their ability to interact with other biomolecules also underpins many regulatory mechanisms critical for life. This versatility and significance in multiple biological contexts firmly establish proteins as the macromolecules that contain the principal components of living organisms.