Here's a breakdown:

* Enzyme: A biological catalyst that speeds up chemical reactions without being consumed in the process.

* Substrate: The specific molecule(s) that an enzyme acts upon.

* Active Site: The region on the enzyme where the substrate binds.

How it works:

1. The substrate binds to the active site of the enzyme.

2. The enzyme facilitates the chemical reaction, transforming the substrate into a product.

3. The product is released from the enzyme, and the enzyme is ready to bind to another substrate.

Example:

* Enzyme: Lactase

* Substrate: Lactose (milk sugar)

* Product: Glucose and galactose

In this case, lactase binds to lactose, breaks it down into glucose and galactose, and then releases the products.