Here's a breakdown:

* Substrate: This is the molecule that the enzyme interacts with and modifies. For example, the enzyme lactase breaks down the substrate lactose.

* Reaction: The type of chemical reaction the enzyme facilitates. For instance, hydrolases break down molecules by adding water, while oxidoreductases catalyze oxidation-reduction reactions.

Often, an enzyme's name will include both elements. For example, DNA polymerase is an enzyme that catalyzes the polymerization (building) of DNA molecules.

Let me know if you'd like more examples or want to explore the naming conventions in more detail!