Question

Assertion : The inhibition of activity of succinic dehydrogenase by malonate which closely resembles the substrate succinate in structure is the example of competitive inhibition.
Reason : Competitive inhibition is the inhibition of enzyme activity when inhibitor closely resembles the substrate, in its molecular structure.

• A. If both assertion and reason are true and reason is the correct explanation of assertion
• B. If both assertion and reason are true but reason is not the correct explanation of assertion
• C. If assertion is true but reason is false
• D. If both assertion and reason are false

Answer 1

Answer: (A)

The activity of an enzyme is sensitive to the presence of specific chemicals that bind to the enzyme. When the binding of the chemical shuts off enzyme activity, the process is called inhibition and the chemical is called an inhibitor. When the inhibitor closely resembles the substrate in its molecular structure and inhibits the activity of the enzyme, it is known as competitive inhibitor. Due to its close structural similarity with the substrate, the inhibitor competes with the substrate for the substrate-binding site of the enzyme. Consequently, the substrate cannot bind and the enzyme action declines. The inhibition of succinic ehydrogenase by malonate which closely resembles the substrate succinate in structure is the example of competitive inhibition.