According to the RNA world hypothesis, why were proteins proposed to replace RNA?

• A. To catalyze reactions
• B. To store genetic information
• C. To provide structural support
• D. To create membranes

Answer: (A)

Proteins were proposed to replace RNA because they offer far greater catalytic versatility. In the RNA world idea, RNA could store information and catalyze reactions, but the diverse set of amino acids and the ability of proteins to fold into a wide range of active sites lets them accelerate many different chemical reactions with higher efficiency and specificity. This expanded catalytic toolkit would support more complex metabolism and evolving life, something RNA alone wouldn’t achieve as robustly. Ribozymes show that RNA can catalyze reactions, but proteins provide a much larger and more versatile set of enzymes. Storing genetic information is primarily an RNA/DNA role, membranes involve lipids, and structural support isn’t the main driving reason for shifting catalytic duties.