Why are enzymes sometimes considered the "lock and key" model?

Question

Why are enzymes sometimes considered the "lock and key" model? Please provide me an easy definition because I have to remember this for a test.

Answer 1

One of the key features of an enzyme is selectivity. That means that an enzyme will only work on a very few substrates, and they usually look similar to one another. The idea of the “lock and key” model is based on this selectivity. Just like a key only fits in one (or a ver few) locks, and a lock is usually only opened by one key, an enzyme will “fit” with a particular substrate like a key fits a lock.