Which statement best describes the relationship between enzymes and substrates?

Enzymes are biological catalysts that speed up chemical reactions in living organisms. They operate by binding to specific substrates, which are the reactants in these reactions. The relationship between enzymes and substrates is characterized by temporary binding, where the enzyme forms a temporary complex with the substrate. This interaction occurs at the enzyme's active site, which is specifically shaped to fit the substrate, much like a key fits into a lock.

This temporary binding is crucial for the catalytic activity of enzymes. Once the reaction takes place, the product is released, and the enzyme remains unchanged and ready to catalyze subsequent reactions with more substrate. This distinctive feature of enzymes allows them to be reused, distinguishing them from other types of biological molecules.

In this context, while some options suggest incorrect relationships, it's essential to understand that the temporary nature of enzyme-substrate binding is what facilitates the chemical reaction without changing the enzyme itself. Thus, the best description of their relationship is that enzymes bind temporarily with substrates.