Chemical reactions within the body sometimes require special proteins called to catalyze the reaction. amino acids nucleic acids enzymes lipids

Enzymes

Enzymes are special proteins which catalyze the reaction within the body. Catalyzing action of enzymes indicates that they complete the reaction before it's usual rate hence, they speed up the chemical reaction. They can make a chemical reaction millions of times faster than it would be without enzyme. The substrate binds to the active site of the enzyme and is converted into products. Once, the product is synthesized it leaves the enzyme and another substrate then binds to the enzyme. That's how enzyme catalyze many product formation.

digestion

it excretes wastes

it provides an alternative energy pathway for the reaction to proceed.

a catalyst is a substance that speeds up the rate of a chemical reaction but is not consumed during the course of the reaction.

catalysts increase the rate of reaction without being used up. they do this by lowering the activation energy needed. with a catalyst, more collisions result in a reaction, so the rate of reaction increases. different reactions need different catalysts.

a catalyst works by providing an alternative reaction pathway to the reaction product. the rate of the reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst.