Provided that there's no diagram, most molecules have particular areas on the molecules, called the "active area" that act as a lock to a particular substrate's molecular structure, providing the key.
An enzyme's active area is only able to be "unlocked" by a certain substrate's "key".
<span>Simply because cells need both these types of molecules for proper function.</span>
Scientist ideas are modified when scientist find more information through experimenting and the scientific method