Lock and Key and Induced Fit Hypothesis

The lock and key hypothesis explains how enzymes work by saying that each enzyme has a specific shape that fits only one type of substrate, just like a key fits only one lock.

Lock and Key Model:
In this idea, the active site of the enzyme is already perfectly shaped for the substrate, so when the correct substrate comes, it fits exactly and the reaction happens quickly. This model shows why enzymes are very specific and only work with certain substances.

Induced Fit Hypothesis:
The induced fit hypothesis gives a more modern and accurate explanation. It says that the active site of the enzyme is not a perfect fit at first. Instead, when the substrate comes close, the enzyme slightly changes its shape to fit the substrate properly. This adjustment creates a better fit and helps the reaction happen more efficiently. After the reaction, the enzyme returns to its original shape and can be used again.

So in simple words, the lock and key model says the enzyme is already perfectly shaped like a lock, while the induced fit model says the enzyme is flexible and changes shape to fit the substrate.