| − | A substance that alters the speed of a chemical reaction but does not get used up in the process.<ref>Wile, Dr. Jay L. ''Exploring Creation With Biology''. Apologia Educational Ministries, Inc. 1998</ref> | + | A substance that alters the speed of a chemical reaction but does not get used up in the process.<ref>Wile, Dr. Jay L. ''Exploring Creation With Biology''. Apologia Educational Ministries, Inc. 1998</ref> A protein that acts as a catalyst is called an [[enzyme]]. |