What is the general function of enzymes within a cell?

• A. They permanently increase the free energy change ($\Delta G$) of reactions to make them proceed faster.
• B. They form the lipid bilayer that separates the cell from its environment.
• C. They act as catalysts that speed up biochemical reactions by lowering activation energy without being consumed.
• D. They provide long-term storage of genetic information used to make proteins.

Answer: (C)