Another science project is here! This one is about Action Molecules!! Press the slide to move to the next one!! Here is a brief explanation from PLTW: Chemical reactions are essential for life and occur in all living tissues. Regulating homeostasis depends upon properly maintaining these reactions. Enzymes are an important component for that maintenance. Enzymes are a type of protein called catalysts. A catalyst facilitates or helps a reaction to occur more readily by reducing the energy required for the reaction to occur. The catalyst is not part of the actual reaction, does not change the chemical reaction, and is not permanently altered by reaction. It does, however, facilitate the reaction and can be used over and over again.