The type of protein or RNA molecule that speeds up metabolic reactions in plants and animals without being permanently changed or destroyed is called an enzyme.

Here's why:

* Catalysts: Enzymes act as catalysts, meaning they accelerate the rate of a chemical reaction without being consumed in the process.

* Specificity: Each enzyme has a specific shape that allows it to bind to a specific molecule (called a substrate). This specificity ensures that the enzyme only catalyzes certain reactions.

* Unchanged: After facilitating the reaction, the enzyme is released unchanged and can catalyze the same reaction again.

While most enzymes are proteins, some are made of RNA molecules, called ribozymes.

Let me know if you'd like to learn more about enzymes!