What is the function of enzymes in biological reactions?

Enzymes play a crucial role in biological reactions as catalysts, which are substances that increase the rate of a reaction without being consumed or permanently altered in the process. By lowering the activation energy required for a reaction to occur, enzymes enable biochemical reactions to proceed more quickly and efficiently at the temperatures typical of living organisms. This catalytic action allows cells to perform essential metabolic processes, such as breaking down nutrients, synthesizing DNA, and generating energy, at a pace suitable for life.

In contrast, increasing the activation energy would slow down reactions, and serving as substrates implies that enzymes would be directly involved in the forming or breaking of bonds in a reaction—not their primary function. Lastly, enzymes are not byproducts of the reactions they facilitate; rather, they remain available to catalyze additional reactions after their initial use. This characteristic makes enzymes vital for sustaining the myriad of biochemical processes that occur in living organisms.