What are organic molecules that catalyze reactions in living system

enzymes

Explanation:

Enzymes are organic molecules made up of proteins that catalyze reactions by either speed up or controlling the chemical reaction.

Enzymes are specific in the reactions they catalyze. An enzyme will only catalyze one specific reaction or a group of closely related reactions. For enzymes to catalyze a reaction, the substrate must fit in the active site on the surface of the enzyme. This forms an enzyme-substrate complex. The enzyme speeds up the formation of the products.