Zymogens protect cells from self-digestion

Steps:

• Proteases are enzymes that break down proteins, so active forms could damage cellular structures.
• Zymogens are inactive precursors synthesized in the rough ER and processed in the Golgi.
• Activation occurs just before secretion, ensuring the enzyme is inactive inside the cell.
• This prevents accidental protein degradation during synthesis and transport.

Why A is correct:

• Zymogens inactivate proteases intracellularly, avoiding autolysis as per enzyme regulation principles in cell biology.

Why the others are wrong:

• B: Activation happens inside the cell; outside, the enzyme targets specific substrates, not avoiding digestion broadly.
• C: Proteases are for extracellular digestion, not cytoplasmic, which would harm the cell.
• D: Rough ER synthesizes zymogens, but they remain inactive there to prevent damage, not to catalyze.

Final answer: A