Question

Ribozymes are:

• A. DNA molecules with catalytic activity
• B. Protein enzymes involved in transcription
• C. RNA molecules having catalytic activity
• D. Lipids involved in protein synthesis

Hint:

Remember that while most enzymes are proteins, ribozymes are a key exception, demonstrating that RNA can also perform catalytic functions. The "ribo" prefix points to RNA.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question asks for the correct definition or nature of ribozymes.

Step 3: Detailed Explanation:
Ribozymes: Ribozymes are ribonucleic acid (RNA) molecules that possess catalytic activity. This means they can catalyze specific biochemical reactions, much like protein enzymes do. The discovery of ribozymes challenged the long-held belief that all biological catalysts are proteins.
Examples: Ribozymes are involved in various crucial cellular processes, including RNA splicing (intron removal), protein synthesis (the peptidyl transferase activity of the ribosome is carried out by ribosomal RNA), and viral replication.
Option Analysis:
- (A) DNA molecules with catalytic activity: DNA typically stores genetic information and does not usually exhibit catalytic activity.
- (B) Protein enzymes involved in transcription: Protein enzymes are catalysts, but transcription is primarily mediated by RNA polymerase (a protein enzyme), and ribozymes are RNA, not protein.
- (C) RNA molecules having catalytic activity: This is the precise definition of ribozymes.
- (D) Lipids involved in protein synthesis: Lipids are structural components and energy stores, not directly involved in protein synthesis as catalytic agents.
Therefore, ribozymes are RNA molecules with catalytic activity.

Step 4: Final Answer:
Ribozymes are RNA molecules having catalytic activity.