Which class of biomolecules is primarily responsible for catalysis, structural support, and signaling?

• A. Carbohydrates
• B. Proteins
• C. Lipids
• D. Nucleic acids

Answer: (B)

Proteins can do it all: they act as enzymes to speed up chemical reactions, provide structural support through fibers like collagen and keratin, and serve in signaling as receptors, hormones, and other signaling molecules. This versatility comes from their diverse shapes and functional groups, which allow them to interact with many different substrates and partners in the cell.

Carbohydrates mainly supply energy and can contribute some structural roles, but they don’t broadly provide catalytic activity. Lipids form membranes and store energy and can participate in signaling in specific contexts, but their primary functions aren’t catalysis or the same level of structural support. Nucleic acids store genetic information, and some RNA molecules have catalytic roles, but they don’t offer the wide range of catalytic, structural, and signaling functions that proteins do.