Answer: Substrate shape exactly fits the rigid active site.
- A Substrate shape exactly fits the rigid active site
- B The enzyme changes shape on substrate binding
- C Multiple substrates share one active site
- D The substrate changes shape
Correct answer: A. Substrate shape exactly fits the rigid active site
Explanation: Lock-and-key model (Fischer): the enzyme has a rigid complementary shape to the substrate, like a lock and key.
Two amino acids join via a condensation reaction: the carboxyl -OH of one and an amine -H of the other are eliminated as water, leaving a peptide bond (-CO-NH-) linking them into a dipeptide; repeating this builds a full protein chain.
Concept context
The chemistry of life: carbohydrates, proteins, lipids, nucleic acids, enzymes, and vitamins. Understand their structures, classification, and biological functions. Highly relevant for NEET and Class 12 board exams.