Which of the following statements regarding enzyme inhibition

1. Competitive inhibition is seen when a substrate competes with an enzyme for binding to an inhibitor protein.
2. Competitive inhibition is seen when the substrate and the inhibitor compete for the active site on the enzyme.
3. Non-competitive inhibition of an enzyme can be overcome by adding large amount of substrate.
4. Non-competitive inhibitors often bind to the enzyme irreversibly.

In competitive inhibition the inhibitor resembles the substrate in structure and hence compete for the active site of the enzyme.