Competitive Enzyme Inhibition — NEET Biology
✅ Asked in NEET 2025A competitive inhibitor competes with the substrate for binding to the
A competitive inhibitor competes with the substrate for binding to the
Inhibition of Succinic dehydrogenase enzyme by malonate is a classical example of:
Malonate inhibits the growth of pathogenic bacteria by inhibiting the activity of:
Answer & NCERT explanation
Correct answer: B — Active site of the enzyme
Competitive inhibitors compete with substrate molecules for binding to the enzyme's active site. According to NCERT, competitive inhibition occurs when inhibitor and substrate have similar structures and both try to bind at the same active site. The inhibitor doesn't bind to allosteric sites or cofactor binding sites.
Read more NCERT concept on the PYQ
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 as a result, the enzyme action declines, e.g., inhibition of succinic dehydrogenase by malonate which closely resembles the substrate succinate in structure. Such competitive inhibitors are often used in the control of bacterial pathogens.
Competitive inhibitors work by structurally mimicking the substrate and competing for the enzyme's active site, thereby reducing enzyme activity. Students often confuse this with non-competitive inhibition, forgetting that competitive inhibitors can be overcome by increasing substrate concentration—the inhibitor doesn't permanently block the enzyme. The key point NTA tests: the inhibitor must structurally resemble the substrate to compete for binding. Remember that malonate inhibiting succinic dehydrogenase is the classic example. Since this concept appeared in 2023, 2024, and 2025 NEET exams, expect questions on enzyme kinetics, the difference between competitive and non-competitive inhibition, or practical applications in controlling bacterial pathogens.
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