What is the role of proteins in biological systems?

Proteins play a crucial role in controlling the structure and function of cells, making this the correct choice. They are fundamental components of cellular architecture, contributing to the structure of cell membranes, organelles, and cytoskeletons. Additionally, proteins serve various functional roles, including enzymes that facilitate biochemical reactions, transport molecules across membranes, and act as signaling molecules to communicate between cells.

While proteins can provide energy under certain conditions, that is not their primary role. The main function of proteins is related to their structural and functional capabilities. Additionally, proteins do not store genetic information; that responsibility falls to nucleic acids like DNA and RNA. Furthermore, while some proteins act as hormones and facilitate chemical reactions, the option specifically highlighting the structural and functional roles of proteins encompasses a broader scope that captures their vital contributions to biological systems.