Chapter 24, Problem 4RQ

In the lock-and-key-model, is a drug viewed as the lock or the key?

To determine

Whether drug is viewed as the lock or the key in the lock-and-key-model.

Answer to Problem 4RQ

The drug viewed as the key. The drug molecule fits into a receptor site the way that key fits into a lock, where they are held together but molecular attractions.

Explanation of Solution

Lock and Key analogy first postulated by Emil Fischer. According to this, lock is the enzyme and key is substrate that will form by the drug. In this model the biological active molecules (from drug) function by fitting into receptor sites in the body. When a drug molecule fits into receptor site as the way a key fits into lock, a particular biological event is triggered, such as nerve impulse or even a chemical reaction.

Conclusion:

Therefore, due to fitting of drug molecule into the receptor site as the way a key fits into a lock, So the drug is viewed as the key.