What is the role of ribozymes in biology?

• A. RNA molecules with catalytic activity (e.g., the ribosome's rRNA catalyzes peptide bond formation)
• B. DNA molecules that code for enzymes
• C. Proteins that assist transcription
• D. Lipids that stabilize membranes

Answer: (A)

Ribozymes are RNA molecules that act as enzymes, catalyzing chemical reactions in cells. A classic example is the ribosome, where the catalytic activity that forms peptide bonds between amino acids is in the ribosomal RNA component, not the protein parts. This shows that RNA can both carry genetic information and function as a catalyst, a relationship that broadens our understanding of how early life could have operated. Other RNA molecules also act as ribozymes, enabling reactions like self-splicing and RNA processing.

The other ideas miss the key point: DNA coding for enzymes describes genetic instructions for protein enzymes, not RNA-based catalysis. Proteins that assist transcription are protein factors, not catalytic RNA. Lipids that stabilize membranes have structural roles, not enzymatic activity.