The function of enzymes in biological processes is to act as catalysts, speeding up reactions by lowering the activation energy needed for those reactions to occur. Enzymes are typically proteins that facilitate a wide range of biochemical reactions, including digestion, metabolism, and DNA replication. Each enzyme has a specific substrate it acts upon, which binds to the enzyme's active site, forming an enzyme-substrate complex. This interaction allows the reaction to occur more efficiently, underscoring the importance of enzymes in maintaining and regulating cellular functions in living organisms.