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Question

Write short notes in 150 words:
Activation energy based mechanism of enzyme action

This question was previously asked in
UPSC CSE 2025 (Prelims) CSAT Official Paper (25-May-2025)

Enzymes are biological catalysts that accelerate chemical reactions by lowering the activation energy, the energy required for reactants to reach the transition state and form products. Without enzymes, many cellular reactions would be too slow to sustain life. Enzymes have a specific active site where substrates bind, forming a temporary enzyme-substrate complex. This complex stabilizes the transition state, aligning reactants precisely and weakening certain bonds to make the reaction easier. For instance, sucrase catalyzes the breakdown of sucrose into glucose and fructose by positioning molecules optimally and forming hydrogen bonds that aid bond cleavage. The induced fit model shows that enzymes slightly adjust their shape to snugly fit the substrate, enhancing efficiency. Enzymes are not consumed in reactions, allowing them to repeatedly catalyze processes essential for life, like metabolism, DNA replication, and energy production. Their activity is influenced by pH, temperature, and inhibitors, reflecting how finely tuned enzymes are to maintain cellular function and homeostasis.

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