Catalyst
MCAT glossary · Chemical & Physical Foundations of Biological Systems
Definition
A substance that lowers the activation energy of a reaction without being consumed.
Catalyst in plain English
A catalyst is a helper that makes a chemical reaction happen faster without getting used up itself. Every reaction has an "energy hill" you must climb to get started (called activation energy), and a catalyst basically finds a shorter, easier path over that hill. Because it isn't consumed, one catalyst can help the same reaction over and over. It's like a mountain guide who shows climbers an easier trail up the peak — the guide speeds everyone through but is still there, ready to help the next group.
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Practice Catalyst
What is the molecular mechanism by which the catalyst achieves this increase?
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